Adding Tube and Chorus and update the way the FXChain is structured

src/fx_chorus.cpp

@@ -0,0 +1,103 @@
+#include "fx_chorus.h"
+
+#include <cmath>
+
+#define CHORUS_BUFFER_SIZE 8192
+
+Chorus::Chorus(float32_t sampling_rate, unsigned voices, float32_t depth, float32_t rate, float32_t feedback) :
+    FXElement(sampling_rate),
+    NumVoices(voices),
+    sample_position_ratio_(sampling_rate / 1000.0f),
+    lfo_phase_(0.0f)
+{
+    this->delay_buffersL_ = new float32_t*[this->NumVoices];
+    this->delay_buffersR_ = new float32_t*[this->NumVoices];
+
+    for(unsigned i = 0; i < this->NumVoices; ++i)
+    {
+        this->delay_buffersL_[i] = new float32_t[CHORUS_BUFFER_SIZE];
+        this->delay_buffersR_[i] = new float32_t[CHORUS_BUFFER_SIZE];
+    }
+
+    this->delay_buffer_indices_ = new unsigned[this->NumVoices];
+    memset(this->delay_buffer_indices_, 0, this->NumVoices * sizeof(float32_t));
+}
+
+Chorus::~Chorus()
+{
+    for(unsigned i = 0; i < this->NumVoices; ++i)
+    {
+        delete[] this->delay_buffersL_[i];
+        delete[] this->delay_buffersR_[i];
+    }
+
+    delete[] this->delay_buffersL_;
+    delete[] this->delay_buffersR_;
+    delete[] this->delay_buffer_indices_;
+}
+
+void Chorus::processSample(float32_t inL, float32_t inR, float32_t& outL, float32_t& outR)
+{
+    static float32_t M2PI = 2.0f * PI;
+
+    float32_t sumL = 0.0f;
+    float32_t sumR = 0.0f;
+    for(unsigned i = 0; i < this->NumVoices; ++i) {
+        // Calculate the delay time based on the depth and rate parameters
+        float32_t delay = this->getDepth() * std::sin(this->lfo_phase_);
+
+        // Convert the delay time to samples
+        unsigned delay_samples = static_cast<unsigned>(delay * this->sample_position_ratio_);
+
+        // Mix the input audio with the delayed audio
+        sumL += inL + this->delay_buffersL_[i][(CHORUS_BUFFER_SIZE + this->delay_buffer_indices_[i] - delay_samples) % CHORUS_BUFFER_SIZE];
+        sumR += inR + this->delay_buffersR_[i][(CHORUS_BUFFER_SIZE + this->delay_buffer_indices_[i] - delay_samples) % CHORUS_BUFFER_SIZE];
+
+        // Update the delay buffer for this voice
+        this->delay_buffersL_[i][this->delay_buffer_indices_[i]] = inL + sumL * this->getFeedback() / static_cast<float32_t>(i + 1);
+        this->delay_buffersR_[i][this->delay_buffer_indices_[i]] = inR + sumR * this->getFeedback() / static_cast<float32_t>(i + 1);
+        this->delay_buffer_indices_[i] = (delay_buffer_indices_[i] + 1) % CHORUS_BUFFER_SIZE;
+    }
+
+    // Average the mixed audio from all voices to create the output
+    outL = sumL / static_cast<float32_t>(this->NumVoices);
+    outR = sumR / static_cast<float32_t>(this->NumVoices);
+
+    this->lfo_phase_ += this->lfo_phase_increment_;
+    if(this->lfo_phase_ > M2PI)
+    {
+        this->lfo_phase_ -= M2PI;
+    }
+}
+
+void Chorus::setDepth(float32_t depth)
+{
+    this->depth_ = constrain(depth, 0.0f, 10.0f);
+}
+
+float32_t Chorus::getDepth() const
+{
+    return this->depth_;
+}
+
+void Chorus::setRate(float32_t rate)
+{
+    this->rate_ = constrain(rate, 0.1f, 1.0f);
+    this->lfo_phase_increment_ = 2.0f * PI * this->rate_ / this->getSamplingRate();
+}
+
+float32_t Chorus::getRate() const
+{
+    return this->rate_;
+}
+
+void Chorus::setFeedback(float32_t feedback)
+{
+    this->feedback_ = constrain(feedback, 0.0f, 1.0f);
+}
+
+float32_t Chorus::getFeedback() const
+{
+    return this->feedback_;
+}
+

src/fx_chorus.h

@@ -0,0 +1,55 @@
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+//
+// fx_chorus.h
+//
+// Stereo Chorus audio effects proposed in the context of the MiniDexed project
+//
+#pragma once
+
+#include "fx.h"
+
+class Chorus : public FXElement
+{
+    DISALLOW_COPY_AND_ASSIGN(Chorus);
+
+public:
+    Chorus(float32_t sampling_rate, unsigned voices = 4, float32_t depth = 5.0f, float32_t rate = 0.5f, float32_t feedback = 0.5f);
+    virtual ~Chorus();
+
+    virtual void processSample(float32_t inL, float32_t inR, float32_t& outL, float32_t& outR) override;
+
+    void setDepth(float32_t depth);
+    inline float32_t getDepth() const;
+
+    void setRate(float32_t rate);
+    inline float32_t getRate() const;
+
+    void setFeedback(float32_t feedback);
+    inline float32_t getFeedback() const;
+
+private:
+    const unsigned NumVoices;   // Number of voices in the chorus
+    const float32_t sample_position_ratio_;
+    float32_t** delay_buffersL_;
+    float32_t** delay_buffersR_;
+    unsigned* delay_buffer_indices_;
+
+    float32_t lfo_phase_;
+    float32_t lfo_phase_increment_;
+
+    float32_t depth_;           // Depth of the chorus in milliseconds (0.0 - 10.0)
+    float32_t rate_;            // Rate of the chorus in Hz (0.1 - 1.0)
+    float32_t feedback_;        // Feedback level of the chorus (0.0 - 1.0)
+};

src/fx_rack.cpp

@@ -1,42 +1,24 @@
 #include "fx_rack.h"
 
-FXUnit::FXUnit(float32_t sampling_rate, FXElement& fx, float32_t wet_level) :
-    FXElement(sampling_rate),
-    fx_(fx)
-{
-    this->setWetLevel(wet_level);
-}
-
-FXUnit::~FXUnit()
-{
-}
-
-void FXUnit::processSample(float32_t inL, float32_t inR, float32_t& outL, float32_t& outR)
-{
-    this->fx_.processSample(inL, inR, outL, outR);
-
-    // Mix wet and dry signals
-    outL = this->getWetLevel() * outL + (1.0f - this->getWetLevel()) * inL;
-    outR = this->getWetLevel() * outR + (1.0f - this->getWetLevel()) * inR;
-}
-
-void FXUnit::setWetLevel(float32_t wet_level)
-{
-    this->wet_level_ = constrain(wet_level, 0.0f, 1.0f);
-}
-
-float32_t FXUnit::getWetLevel() const
-{
-    return this->wet_level_;
-}
-
 FXRack::FXRack(float32_t sampling_rate) :
     FX(sampling_rate),
     fx_chain_()
 {
-    this->registerFX(new Phaser(sampling_rate));
-    this->registerFX(new TapeDelay(sampling_rate));
-    this->registerFX(new ShimmerReverb(sampling_rate));
+    this->fxTube_ = new FXUnit<Tube>(sampling_rate);
+    this->fxChorus_ = new FXUnit<Chorus>(sampling_rate);
+    this->fxFlanger_ = new FXUnit<Flanger>(sampling_rate);
+    this->fxOrbitone_ = new FXUnit<Orbitone>(sampling_rate);
+    this->fxPhaser_ = new FXUnit<Phaser>(sampling_rate);
+    this->fxTapeDelay_ = new FXUnit<TapeDelay>(sampling_rate);
+    this->fxShimmerReverb_ = new FXUnit<ShimmerReverb>(sampling_rate);
+
+    this->registerFX(this->fxTube_);
+    this->registerFX(this->fxChorus_);
+    this->registerFX(this->fxFlanger_);
+    this->registerFX(this->fxOrbitone_);
+    this->registerFX(this->fxPhaser_);
+    this->registerFX(this->fxTapeDelay_);
+    this->registerFX(this->fxShimmerReverb_);
 }
 
 FXRack::~FXRack()
@@ -46,6 +28,14 @@ FXRack::~FXRack()
         delete *it;
     }
     this->fx_chain_.clear();
+
+    delete this->fxTube_;
+    delete this->fxChorus_;
+    delete this->fxFlanger_;
+    delete this->fxOrbitone_;
+    delete this->fxPhaser_;
+    delete this->fxTapeDelay_;
+    delete this->fxShimmerReverb_;
 }
 
 void FXRack::process(float32_t* left_input, float32_t* right_input, float32_t* left_output, float32_t* right_output, size_t nSamples)
@@ -85,5 +75,5 @@ void FXRack::process(float32_t* left_input, float32_t* right_input, float32_t* l
 
 void FXRack::registerFX(FXElement* fx)
 {
-    this->fx_chain_.push_back(new FXUnit(this->getSamplingRate(), *fx));
+    this->fx_chain_.push_back(fx);
 }

src/fx_rack.h

@@ -20,31 +20,63 @@
 #pragma once
 
 #include "fx.h"
+#include "fx_tube.h"
+#include "fx_chorus.h"
+#include "fx_flanger.h"
+#include "fx_orbitone.h"
 #include "fx_phaser.h"
 #include "fx_tape_delay.h"
 #include "fx_shimmer_reverb.h"
 
 #include <vector>
 
-class FXUnit : public FXElement
+template<typename _FXElement>
+class FXUnit : public virtual _FXElement
 {
     DISALLOW_COPY_AND_ASSIGN(FXUnit);
 
 public:
-    FXUnit(float32_t sampling_rate, FXElement& fx, float32_t wet_level = 0.5f);
-    virtual ~FXUnit();
+    FXUnit(float32_t sampling_rate, float32_t wet_level = 0.5f) :
+        _FXElement(sampling_rate),
+        wet_level_(wet_level)
+    {
+    }
 
-    virtual void processSample(float32_t inL, float32_t inR, float32_t& outL, float32_t& outR) override;
+    virtual ~FXUnit()
+    {
+    }
 
-    void setWetLevel(float32_t wet_level);
-    inline float32_t getWetLevel() const;
+    void processSample(float32_t inL, float32_t inR, float32_t& outL, float32_t& outR)
+    {
+        if(this->getWetLevel() == 0.0f)
+        {
+            outL = inL;
+            outR = inR;
+        }
+        else
+        {
+            _FXElement::processSample(inL, inR, outL, outR);
+            float32_t dry = 1.0f - this->getWetLevel();
+            outL = this->getWetLevel() * outL + dry * inL;
+            outR = this->getWetLevel() * outR + dry * inR;
+        }
+    }
+
+    void setWetLevel(float32_t wet_level)
+    {
+        this->wet_level_ = constrain(wet_level, 0.0f, 1.0f);
+    }
+
+    inline float32_t getWetLevel() const
+    {
+        return this->wet_level_;
+    }
 
 private:
-    FXElement& fx_;         // Embedded FX
     float32_t wet_level_;   // How much the signal is affected by the inner FX (0.0 - 1.0)
 };
 
-typedef std::vector<FXUnit*> FXChain;
+typedef std::vector<FXElement*> FXChain;
 
 class FXRack : public FX
 {
@@ -60,4 +92,11 @@ private:
     void registerFX(FXElement* fx);
 
     FXChain fx_chain_;
+    FXUnit<Tube>* fxTube_;
+    FXUnit<Chorus>* fxChorus_;
+    FXUnit<Flanger>* fxFlanger_;
+    FXUnit<Orbitone>* fxOrbitone_;
+    FXUnit<Phaser>* fxPhaser_;
+    FXUnit<TapeDelay>* fxTapeDelay_;
+    FXUnit<ShimmerReverb>* fxShimmerReverb_;
 };

src/fx_tube.cpp

@@ -0,0 +1,60 @@
+#include "fx_tube.h"
+
+#include <cmath>
+
+Tube::Tube(float32_t samplingRate, float32_t curve, float32_t bias) :
+    FXElement(samplingRate),
+    TubeCurve(curve),
+    TubeBias(bias)
+{
+}
+
+Tube::~Tube()
+{
+}
+
+void Tube::processSample(float32_t inL, float32_t inR, float32_t& outL, float32_t& outR)
+{
+    float32_t absInL = abs(inL);
+
+    float32_t coeff = this->TubeCurve + this->getOverdrive();
+
+    if(absInL > this->TubeBias) 
+    {
+        outL = coeff * (absInL - this->TubeBias) / (1.0f - this->TubeBias);
+    }
+    else
+    {
+        outL = coeff * absInL / (1.0f + this->TubeBias * absInL);
+    }
+
+    if(inL < 0.0f)
+    {
+        outL = -outL;
+    }
+
+    float32_t absInR = abs(inR);
+    if(absInR > this->TubeBias) 
+    {
+        outR = coeff * (absInR - this->TubeBias) / (1.0f - this->TubeBias);
+    }
+    else
+    {
+        outR = coeff * absInR / (1.0f + this->TubeBias * absInR);
+    }
+
+    if(inR < 0.0f)
+    {
+        outR = -outR;
+    }
+}
+
+void Tube::setOverdrive(float32_t overdrive)
+{
+    this->overdrive_ = constrain(overdrive, 0.0f, 1.0f);
+}
+
+float32_t Tube::getOverdrive() const
+{
+    return this->overdrive_;
+}

src/fx_tube.h

@@ -0,0 +1,41 @@
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+//
+// fx_tube.h
+//
+// Stereo Tube overdrive audio effects proposed in the context of the MiniDexed project
+//
+#pragma once
+
+#include "fx.h"
+
+class Tube : public FXElement
+{
+    DISALLOW_COPY_AND_ASSIGN(Tube);
+
+public:
+    Tube(float32_t sampling_rate, float32_t curve = 2.0f, float32_t bias = 0.7f);
+    virtual ~Tube();
+
+    virtual void processSample(float32_t inL, float32_t inR, float32_t& outL, float32_t& outR) override;
+
+    void setOverdrive(float32_t overdrive);
+    inline float32_t getOverdrive() const;
+
+private:
+    const float32_t TubeCurve;
+    const float32_t TubeBias;
+
+    float32_t overdrive_;
+};