ToneGenBase.cpp

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/**********************************************************************
 
  Audacity: A Digital Audio Editor
 
  Split from ToneGen.cpp
 
  Steve Jolly
  James Crook (Adapted for 'Chirps')
 
  This class implements a tone generator effect.
 
*******************************************************************//*******************************************************************/
#include "ToneGenBase.h"
#include "Project.h"
#include "ProjectRate.h"
#include "ShuttleAutomation.h"
#include <math.h>
 
const EnumValueSymbol ToneGenBase::kInterStrings[nInterpolations] = {
   // These are acceptable dual purpose internal/visible names
   { XO("Linear") },
   { XO("Logarithmic") }
};
 
const EnumValueSymbol ToneGenBase::kWaveStrings[nWaveforms] = {
   { XO("Sine") },
   { XO("Square") },
   { XO("Sawtooth") },
   { XO("Square, no alias") },
   { XC("Triangle", "waveform") }
};
 
const EffectParameterMethods& ToneGenBase::Parameters() const
{
   static const auto postSet = [](ToneGenBase&, EffectSettings&, ToneGenBase& e,
                                  bool updating) {
      if (updating)
         e.PostSet();
      return true;
   };
   static CapturedParameters<
      ToneGenBase, StartFreq, EndFreq, StartAmp, EndAmp, Waveform, Interp>
      chirpParameters { postSet };
   static CapturedParameters<
      ToneGenBase, Frequency, Amplitude, Waveform, Interp>
      toneParameters { postSet };
   if (mChirp)
      return chirpParameters;
   else
      return toneParameters;
}
 
ToneGenBase::ToneGenBase(bool isChirp)
    : mChirp { isChirp }
{
   Parameters().Reset(*this);
 
   wxASSERT(nWaveforms == WXSIZEOF(kWaveStrings));
   wxASSERT(nInterpolations == WXSIZEOF(kInterStrings));
 
   // Chirp varies over time so must use selected duration.
   // TODO: When previewing, calculate only the first 'preview length'.
   if (isChirp)
      SetLinearEffectFlag(false);
   else
      SetLinearEffectFlag(true);
}
 
ToneGenBase::~ToneGenBase()
{
}
 
// EffectDefinitionInterface implementation
 
EffectType ToneGenBase::GetType() const
{
   return EffectTypeGenerate;
}
 
unsigned ToneGenBase::GetAudioOutCount() const
{
   return 1;
}
 
bool ToneGenBase::ProcessInitialize(
   EffectSettings&, double sampleRate, ChannelNames chanMap)
{
   mSampleRate = sampleRate;
   mPositionInCycles = 0.0;
   mSample = 0;
   return true;
}
 
size_t ToneGenBase::ProcessBlock(
   EffectSettings&, const float* const*, float* const* outBlock,
   size_t blockLen)
{
   float* buffer = outBlock[0];
   double throwaway = 0; // passed to modf but never used
   double f = 0.0;
   double a, b;
   int k;
 
   double frequencyQuantum;
   double BlendedFrequency;
   double BlendedAmplitude;
   double BlendedLogFrequency = 0.0;
 
   // calculate delta, and reposition from where we left
   auto doubleSampleCount = mSampleCnt.as_double();
   auto doubleSample = mSample.as_double();
   double amplitudeQuantum = (mAmplitude1 - mAmplitude0) / doubleSampleCount;
   BlendedAmplitude = mAmplitude0 + amplitudeQuantum * doubleSample;
 
   // precalculations:
   double pre2PI = 2.0 * M_PI;
   double pre4divPI = 4.0 / M_PI;
 
   // initial setup should calculate deltas
   if (mInterpolation == kLogarithmic)
   {
      // this for log interpolation
      mLogFrequency[0] = log10(mFrequency0);
      mLogFrequency[1] = log10(mFrequency1);
      // calculate delta, and reposition from where we left
      frequencyQuantum =
         (mLogFrequency[1] - mLogFrequency[0]) / doubleSampleCount;
      BlendedLogFrequency = mLogFrequency[0] + frequencyQuantum * doubleSample;
      BlendedFrequency = pow(10.0, BlendedLogFrequency);
   }
   else
   {
      // this for regular case, linear interpolation
      frequencyQuantum = (mFrequency1 - mFrequency0) / doubleSampleCount;
      BlendedFrequency = mFrequency0 + frequencyQuantum * doubleSample;
   }
 
   // synth loop
   for (decltype(blockLen) i = 0; i < blockLen; i++)
   {
      switch (mWaveform)
      {
      case kSine:
         f = sin(pre2PI * mPositionInCycles / mSampleRate);
         break;
      case kSquare:
         f = (modf(mPositionInCycles / mSampleRate, &throwaway) < 0.5) ? 1.0 :
                                                                         -1.0;
         break;
      case kSawtooth:
         f = (2.0 * modf(mPositionInCycles / mSampleRate + 0.5, &throwaway)) -
             1.0;
         break;
      case kTriangle:
         f = modf(mPositionInCycles / mSampleRate, &throwaway);
         if (f < 0.25)
         {
            f *= 4.0;
         }
         else if (f > 0.75)
         {
            f = (f - 1.0) * 4.0;
         }
         else
         { /* f >= 0.25 || f <= 0.75 */
            f = (0.5 - f) * 4.0;
         }
         break;
      case kSquareNoAlias: // Good down to 110Hz @ 44100Hz sampling.
         // do fundamental (k=1) outside loop
         b = (1.0 + cos((pre2PI * BlendedFrequency) / mSampleRate)) /
             pre4divPI; // scaling
         f = pre4divPI * sin(pre2PI * mPositionInCycles / mSampleRate);
         for (k = 3; (k < 200) && (k * BlendedFrequency < mSampleRate / 2.0);
              k += 2)
         {
            // Hann Window in freq domain
            a = 1.0 + cos((pre2PI * k * BlendedFrequency) / mSampleRate);
            // calc harmonic, apply window, scale to amplitude of fundamental
            f +=
               a * sin(pre2PI * mPositionInCycles / mSampleRate * k) / (b * k);
         }
      }
      // insert value in buffer
      buffer[i] = (float)(BlendedAmplitude * f);
      // update freq,amplitude
      mPositionInCycles += BlendedFrequency;
      BlendedAmplitude += amplitudeQuantum;
      if (mInterpolation == kLogarithmic)
      {
         BlendedLogFrequency += frequencyQuantum;
         BlendedFrequency = pow(10.0, BlendedLogFrequency);
      }
      else
      {
         BlendedFrequency += frequencyQuantum;
      }
   }
 
   // update external placeholder
   mSample += blockLen;
 
   return blockLen;
}
 
void ToneGenBase::PostSet()
{
   if (!mChirp)
   {
      mFrequency1 = mFrequency0;
      mAmplitude1 = mAmplitude0;
   }
   //   double freqMax =
   //      (FindProject()
   //         ? ProjectRate::Get( *FindProject() ).GetRate()
   //         : 44100.0)
   //      / 2.0;
   //   mFrequency1 = std::clamp<double>(mFrequency1, EndFreq.min, freqMax);
}