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オーディオプラグインの作成、パート11

シリーズのすべての投稿：
パート1.紹介とセットアップ
パート2.コードの学習
パート3. VSTおよびAU
パート4.デジタル歪み
パート5.プリセットとGUI
パート6.信号合成
パート7. MIDIメッセージの受信
パート8.仮想キーボード
パート9.封筒
パート10. GUIの改善
パート11.フィルター
パート12.低周波発振器
パート13.再設計
パート14.ポリフォニー1
パート15.ポリフォニー2
パート16.アンチエイリアス


今日は、共振フィルターを作成します。 フィルタ設計は複雑な領域であり、世界中の多くのDSPエンジニアが困惑しています。 ジャングルに飛び込むのではなく、 Paul Kellet アルゴリズムに基づいて単純なローパスフィルター （ Low-Pass ）、 バンドパス （ Band-Pass ）、およびハイパスフィルター （ High-Pass ）を作成します

ご想像のとおり、 Filterクラスを作成することから始めましょう。 削除する
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter

#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter

#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter

#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter

#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter

#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter

#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter

#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter

#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter

#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter

#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter
 #include  Filter.h ( )     : 
 
 class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; }; 
 
  private       cutoff   resonance . Mode      (Lowpass, Highpass, Bandpass).  feedbackAmount , buf0  buf1    ,    . 
          ( calculateFeedbackAmount() ).  process      .   feedbackAmount   cutoff  resonance ,    calculateFeedbackAmount      . 
 
   Filter.cpp  : 
 
 // By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } } 
 
 , ?  ,           . « »   ,               (. .    6 ).     buf0  buf1 :        .     inputValue ,  - buf0 (  ).   .    6 /   12 /.  switch ,  buf1    . , ,    buf0 ,       12,   6 /,        . 
 
  case FILTER_MODE_HIGHPASS    . buf0       .   inputValue  buf0 ,   .    buf1 ,     . 
 
  case FILTER_MODE_BANDPASS ,  buf0 - buf1   .  buf0       ,     buf1 . ,   . 
  :           ,   . 
 
  buf1     .            ( Infinite Impulse Response ,  IIR ).    ,      .      ,         ,      . 
 
   
       ,     ,     .   ,  ,      ,  ,          .           ,  NI Massive,   «    ».       ,          ,   .        ,          (  Massive       ).      «» , , , AAS Ultra Analog,       ,     ,    ,        .         ,  ,     ,   ,      NI Reaktor. ,            —    ,    ..     . 
 
   
     .   GUI.  bg.png   ( “Move to trash”  Xcode),       : 
 
 filtermode.png knob_small.png (  ,   50 50 ) bg.png (       ) 
 
    ID  resource.h : 
 
 // Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png" 
 
  Synthesis.rc : 
 
 #include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN 
 
   #include "Filter.h"  Synthesis.h    private : 
 
 Filter mFilter; 
 
  EParams  Synthesis.cpp : 
 
 enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams }; 
 
        : 
 
 pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap)); 
 
      .      (Lowpass, Highpass, Bandpass).    AttachGraphics(pGraphics) : 
 
 GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap)); 
 
         .    .     knob_small.png : 
 
 // Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap)); 
 
   ,           1.0 ,   calculateFeedbackAmount    , . 
  ProcessDoubleReplacing     : 
 
 leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0); 
 
       .  switch   Synthesis::OnParamChange : 
 
 case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break; 
 
    .  -      . 
 
  
 
  —      .   ,   ,          . 
      : 
 
 buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); 
 
 ,   ,      ( buf0 – buf1 ),   feedbackAmount .    calculateFeedbackAmount  feedbackAmount  resonance , . .    ,   . 
 
  ,            .     ,   ,        .    ,        ,       . 
 
  -12 /  -24 / 
        !     24   .     switch  Filter::process : 
 
 buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3); 
 
   :      ,       ,            .     ,       , ,  (       ).     switch : 
 
 switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; } 
 
   buf1  buf3 –      .    -24 /.     buf2  buf3 ,        private Filter.h : 
 
 double buf2; double buf3; 
 
    ,   buf0 c buf1 : 
 
 Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ... 
 
     , ,     :     .       . 
          ? 
 
   
    .  ,           ,       . 
 -      cutoff   .      .    cutoffMod ,    ,       cutoff    .     #include    private : 
 
 double cutoffMod; 
 
 : 
 
 Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ... 
 
         .   private : 
 
 inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); }; 
 
 calculateFeedbackAmount     : 
 
 inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); } 
 
       cutoffMod .   feedbackAmount    ,     : 
 
 inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); } 
 
 ,       .   Filter::process   : 
 
 if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3); 
 
        ,    .    ,      ,   .     .     cutoff  calculatedCutoff   -. 
 
 ,       ( setCutoffMod ),   Synthesis    ,     ,    .    ,        cutoffMod .    filterEnvelopeAmount    -1  +1 .   GUI. 
 
   private Synthesis.h    : 
 
 EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount; 
 
       MIDI ,      onNoteOn  onNoteOff : 
 
 inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); }; 
 
    .   ProcessDoubleReplacing        : 
 
 mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount); 
 
  ,        nextSample  filterEnvelopeAmount     cutoffMod .     filterEnvelopeAmount  : 
 
 Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... } 
 
       Synthesis::Reset : 
 
 mFilterEnvelopeGenerator.setSampleRate(GetSampleRate()); 
 
      EParams ,       .  AttachGraphics     : 
 
 // Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap)); 
 
     ,       smallKnobBitmap .                   .     ,    .  Synthesis::OnParamChange    switch : 
 
 case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break; 
 
 ! 
     !           (-   C1),   : 
 
  
 
        EnvelopeGenerator  .         .        ! 
 
     . 
 
        :) 
 
  : 
 martin-finke.de/blog/articles/audio-plugins-013-filter
#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter

#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter

#include Filter.h ( ) :

class Filter { public: enum FilterMode { FILTER_MODE_LOWPASS = 0, FILTER_MODE_HIGHPASS, FILTER_MODE_BANDPASS, kNumFilterModes }; Filter() : cutoff(0.99), resonance(0.0), mode(FILTER_MODE_LOWPASS), buf0(0.0), buf1(0.0) { calculateFeedbackAmount(); }; double process(double inputValue); inline void setCutoff(double newCutoff) { cutoff = newCutoff; calculateFeedbackAmount(); }; inline void setResonance(double newResonance) { resonance = newResonance; calculateFeedbackAmount(); }; inline void setFilterMode(FilterMode newMode) { mode = newMode; } private: double cutoff; double resonance; FilterMode mode; double feedbackAmount; inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - cutoff); } double buf0; double buf1; };

private cutoff resonance . Mode (Lowpass, Highpass, Bandpass). feedbackAmount , buf0 buf1 , .
( calculateFeedbackAmount() ). process . feedbackAmount cutoff resonance , calculateFeedbackAmount .

Filter.cpp :

// By Paul Kellett // http://www.musicdsp.org/showone.php?id=29 double Filter::process(double inputValue) { buf0 += cutoff * (inputValue - buf0); buf1 += cutoff * (buf0 - buf1); switch (mode) { case FILTER_MODE_LOWPASS: return buf1; case FILTER_MODE_HIGHPASS: return inputValue - buf0; case FILTER_MODE_BANDPASS: return buf0 - buf1; default: return 0.0; } }

, ? , . « » , (. . 6 ). buf0 buf1 : . inputValue , - buf0 ( ). . 6 / 12 /. switch , buf1 . , , buf0 , 12, 6 /, .

case FILTER_MODE_HIGHPASS . buf0 . inputValue buf0 , . buf1 , .

case FILTER_MODE_BANDPASS , buf0 - buf1 . buf0 , buf1 . , .
: , .

buf1 . ( Infinite Impulse Response , IIR ). , . , , .


, , . , , , , . , NI Massive, « ». , , . , ( Massive ). «» , , , AAS Ultra Analog, , , , . , , , , NI Reaktor. , — , .. .


. GUI. bg.png ( “Move to trash” Xcode), :

filtermode.png knob_small.png ( , 50 50 ) bg.png ( )

ID resource.h :

// Unique IDs for each image resource. #define BG_ID 101 #define WHITE_KEY_ID 102 #define BLACK_KEY_ID 103 #define WAVEFORM_ID 104 #define KNOB_ID 105 #define KNOB_SMALL_ID 106 #define FILTERMODE_ID 107 // Image resource locations for this plug. #define BG_FN "resources/img/bg.png" #define WHITE_KEY_FN "resources/img/whitekey.png" #define BLACK_KEY_FN "resources/img/blackkey.png" #define WAVEFORM_FN "resources/img/waveform.png" #define KNOB_FN "resources/img/knob.png" #define KNOB_SMALL_FN "resources/img/knob_small.png" #define FILTERMODE_FN "resources/img/filtermode.png"

Synthesis.rc :

#include "resource.h" BG_ID PNG BG_FN WHITE_KEY_ID PNG WHITE_KEY_FN BLACK_KEY_ID PNG BLACK_KEY_FN WAVEFORM_ID PNG WAVEFORM_FN KNOB_ID PNG KNOB_FN KNOB_SMALL_ID PNG KNOB_SMALL_FN FILTERMODE_ID PNG FILTERMODE_FN

#include "Filter.h" Synthesis.h private :

Filter mFilter;

EParams Synthesis.cpp :

enum EParams { mWaveform = 0, mAttack, mDecay, mSustain, mRelease, mFilterMode, mFilterCutoff, mFilterResonance, mFilterAttack, mFilterDecay, mFilterSustain, mFilterRelease, mFilterEnvelopeAmount, kNumParams };

:

pGraphics->AttachControl(new ISwitchControl(this, 24, 38, mWaveform, &waveformBitmap));

. (Lowpass, Highpass, Bandpass). AttachGraphics(pGraphics) :

GetParam(mFilterMode)->InitEnum("Filter Mode", Filter::FILTER_MODE_LOWPASS, Filter::kNumFilterModes); IBitmap filtermodeBitmap = pGraphics->LoadIBitmap(FILTERMODE_ID, FILTERMODE_FN, 3); pGraphics->AttachControl(new ISwitchControl(this, 24, 123, mFilterMode, &filtermodeBitmap));

. . knob_small.png :

// Knobs for filter cutoff and resonance IBitmap smallKnobBitmap = pGraphics->LoadIBitmap(KNOB_SMALL_ID, KNOB_SMALL_FN, 64); // Cutoff knob: GetParam(mFilterCutoff)->InitDouble("Cutoff", 0.99, 0.01, 0.99, 0.001); GetParam(mFilterCutoff)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 5, 177, mFilterCutoff, &smallKnobBitmap)); // Resonance knob: GetParam(mFilterResonance)->InitDouble("Resonance", 0.01, 0.01, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 61, 177, mFilterResonance, &smallKnobBitmap));

, 1.0 , calculateFeedbackAmount , .
ProcessDoubleReplacing :

leftOutput[i] = rightOutput[i] = mFilter.process(mOscillator.nextSample() * mEnvelopeGenerator.nextSample() * velocity / 127.0);

. switch Synthesis::OnParamChange :

case mFilterCutoff: mFilter.setCutoff(GetParam(paramIdx)->Value()); break; case mFilterResonance: mFilter.setResonance(GetParam(paramIdx)->Value()); break; case mFilterMode: mFilter.setFilterMode(static_cast<Filter::FilterMode>(GetParam(paramIdx)->Int())); break;

. - .



— . , , .
:

buf0 += cutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1));

, , ( buf0 – buf1 ), feedbackAmount . calculateFeedbackAmount feedbackAmount resonance , . . , .

, . , , . , , .

-12 / -24 /
! 24 . switch Filter::process :

buf2 += cutoff * (buf1 - buf2); buf3 += cutoff * (buf2 – buf3);

: , , . , , , ( ). switch :

switch (mode) { case FILTER_MODE_LOWPASS: return buf3; case FILTER_MODE_HIGHPASS: return inputValue - buf3; case FILTER_MODE_BANDPASS: return buf0 - buf3; default: return 0.0; }

buf1 buf3 – . -24 /. buf2 buf3 , private Filter.h :

double buf2; double buf3;

, buf0 c buf1 :

Filter() : // ... buf0(0.0), buf1(0.0), buf2(0.0), buf3(0.0) // ...

, , : . .
?


. , , .
- cutoff . . cutoffMod , , cutoff . #include private :

double cutoffMod;

:

Filter() : cutoff(0.99), resonance(0.01), cutoffMod(0.0), // ...

. private :

inline double getCalculatedCutoff() const { return fmax(fmin(cutoff + cutoffMod, 0.99), 0.01); };

calculateFeedbackAmount :

inline void calculateFeedbackAmount() { feedbackAmount = resonance + resonance/(1.0 - getCalculatedCutoff()); }

cutoffMod . feedbackAmount , :

inline void setCutoffMod(double newCutoffMod) { cutoffMod = newCutoffMod; calculateFeedbackAmount(); }

, . Filter::process :

if (inputValue == 0.0) return inputValue; double calculatedCutoff = getCalculatedCutoff(); buf0 += calculatedCutoff * (inputValue - buf0 + feedbackAmount * (buf0 - buf1)); buf1 += calculatedCutoff * (buf0 - buf1); buf2 += calculatedCutoff * (buf1 - buf2); buf3 += calculatedCutoff * (buf2 – buf3);

, . , , . . cutoff calculatedCutoff -.

, ( setCutoffMod ), Synthesis , , . , cutoffMod . filterEnvelopeAmount -1 +1 . GUI.

private Synthesis.h :

EnvelopeGenerator mFilterEnvelopeGenerator; double filterEnvelopeAmount;

MIDI , onNoteOn onNoteOff :

inline void onNoteOn(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK); }; inline void onNoteOff(const int noteNumber, const int velocity) { mEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); mFilterEnvelopeGenerator.enterStage(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE); };

. ProcessDoubleReplacing :

mFilter.setCutoffMod(mFilterEnvelopeGenerator.nextSample() * filterEnvelopeAmount);

, nextSample filterEnvelopeAmount cutoffMod . filterEnvelopeAmount :

Synthesis::Synthesis(IPlugInstanceInfo instanceInfo) : IPLUG_CTOR(kNumParams, kNumPrograms, instanceInfo), lastVirtualKeyboardNoteNumber(virtualKeyboardMinimumNoteNumber - 1), filterEnvelopeAmount(0.0) { // ... }

Synthesis::Reset :

mFilterEnvelopeGenerator.setSampleRate(GetSampleRate());

EParams , . AttachGraphics :

// Knobs for filter envelope // Attack knob GetParam(mFilterAttack)->InitDouble("Filter Env Attack", 0.01, 0.01, 10.0, 0.001); GetParam(mFilterAttack)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 139, 178, mFilterAttack, &smallKnobBitmap)); // Decay knob: GetParam(mFilterDecay)->InitDouble("Filter Env Decay", 0.5, 0.01, 15.0, 0.001); GetParam(mFilterDecay)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 195, 178, mFilterDecay, &smallKnobBitmap)); // Sustain knob: GetParam(mFilterSustain)->InitDouble("Filter Env Sustain", 0.1, 0.001, 1.0, 0.001); GetParam(mFilterSustain)->SetShape(2); pGraphics->AttachControl(new IKnobMultiControl(this, 251, 178, mFilterSustain, &smallKnobBitmap)); // Release knob: GetParam(mFilterRelease)->InitDouble("Filter Env Release", 1.0, 0.001, 15.0, 0.001); GetParam(mFilterRelease)->SetShape(3); pGraphics->AttachControl(new IKnobMultiControl(this, 307, 178, mFilterRelease, &smallKnobBitmap)); // Filter envelope amount knob: GetParam(mFilterEnvelopeAmount)->InitDouble("Filter Env Amount", 0.0, -1.0, 1.0, 0.001); pGraphics->AttachControl(new IKnobMultiControl(this, 363, 178, mFilterEnvelopeAmount, &smallKnobBitmap));

, smallKnobBitmap . . , . Synthesis::OnParamChange switch :

case mFilterAttack: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_ATTACK, GetParam(paramIdx)->Value()); break; case mFilterDecay: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_DECAY, GetParam(paramIdx)->Value()); break; case mFilterSustain: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_SUSTAIN, GetParam(paramIdx)->Value()); break; case mFilterRelease: mFilterEnvelopeGenerator.setStageValue(EnvelopeGenerator::ENVELOPE_STAGE_RELEASE, GetParam(paramIdx)->Value()); break; case mFilterEnvelopeAmount: filterEnvelopeAmount = GetParam(paramIdx)->Value(); break;

!
! (- C1), :



EnvelopeGenerator . . !

.

:)

:
martin-finke.de/blog/articles/audio-plugins-013-filter


Source: https://habr.com/ru/post/J227791/

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