WahWahBase.cpp

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/**********************************************************************
 
  Audacity: A Digital Audio Editor
 
  WahwahBase.cpp
 
  Nasca Octavian Paul (Paul Nasca)
 
*******************************************************************//*******************************************************************/
#include "WahWahBase.h"
 
const EffectParameterMethods& WahWahBase::Parameters() const
{
   static CapturedParameters<
      WahWahBase, Freq, Phase, Depth, Res, FreqOfs, OutGain>
      parameters;
   return parameters;
}
 
// How many samples are processed before recomputing the lfo value again
#define lfoskipsamples 30
 
//
// WahWahBase
//
 
const ComponentInterfaceSymbol WahWahBase::Symbol { XO("Wahwah") };
 
std::shared_ptr<EffectInstance> WahWahBase::MakeInstance() const
{
   return std::make_shared<Instance>(*this);
}
 
WahWahBase::WahWahBase()
{
   SetLinearEffectFlag(true);
}
 
WahWahBase::~WahWahBase()
{
}
 
// ComponentInterface implementation
 
ComponentInterfaceSymbol WahWahBase::GetSymbol() const
{
   return Symbol;
}
 
TranslatableString WahWahBase::GetDescription() const
{
   return XO(
      "Rapid tone quality variations, like that guitar sound so popular in the 1970's");
}
 
ManualPageID WahWahBase::ManualPage() const
{
   return L"Wahwah";
}
 
// EffectDefinitionInterface implementation
 
EffectType WahWahBase::GetType() const
{
   return EffectTypeProcess;
}
 
auto WahWahBase::RealtimeSupport() const -> RealtimeSince
{
   return RealtimeSince::After_3_1;
}
 
bool WahWahBase::Instance::ProcessInitialize(
   EffectSettings& settings, double sampleRate, ChannelNames chanMap)
{
   InstanceInit(settings, mState, sampleRate);
   if (chanMap[0] == ChannelNameFrontRight)
      mState.phase += M_PI;
   return true;
}
 
size_t WahWahBase::Instance::ProcessBlock(
   EffectSettings& settings, const float* const* inBlock,
   float* const* outBlock, size_t blockLen)
{
   return InstanceProcess(settings, mState, inBlock, outBlock, blockLen);
}
 
bool WahWahBase::Instance::RealtimeInitialize(EffectSettings&, double)
{
   SetBlockSize(512);
   mSlaves.clear();
   return true;
}
 
bool WahWahBase::Instance::RealtimeAddProcessor(
   EffectSettings& settings, EffectOutputs*, unsigned, float sampleRate)
{
   WahWahBase::Instance slave(mProcessor);
 
   InstanceInit(settings, slave.mState, sampleRate);
 
   mSlaves.push_back(slave);
 
   return true;
}
 
bool WahWahBase::Instance::RealtimeFinalize(EffectSettings&) noexcept
{
   mSlaves.clear();
 
   return true;
}
 
size_t WahWahBase::Instance::RealtimeProcess(
   size_t group, EffectSettings& settings, const float* const* inbuf,
   float* const* outbuf, size_t numSamples)
{
   if (group >= mSlaves.size())
      return 0;
   return InstanceProcess(
      settings, mSlaves[group].mState, inbuf, outbuf, numSamples);
}
 
// WahWahBase implementation
 
void WahWahBase::Instance::InstanceInit(
   EffectSettings& settings, EffectWahwahState& data, float sampleRate)
{
   auto& ms = GetSettings(settings);
 
   data.samplerate = sampleRate;
   data.lfoskip = ms.mFreq * 2 * M_PI / sampleRate;
   data.skipcount = 0;
   data.xn1 = 0;
   data.xn2 = 0;
   data.yn1 = 0;
   data.yn2 = 0;
   data.b0 = 0;
   data.b1 = 0;
   data.b2 = 0;
   data.a0 = 0;
   data.a1 = 0;
   data.a2 = 0;
 
   data.depth = ms.mDepth / 100.0;
   data.freqofs = ms.mFreqOfs / 100.0;
   data.phase = ms.mPhase * M_PI / 180.0;
   data.outgain = DB_TO_LINEAR(ms.mOutGain);
}
 
size_t WahWahBase::Instance::InstanceProcess(
   EffectSettings& settings, EffectWahwahState& data,
   const float* const* inBlock, float* const* outBlock, size_t blockLen)
{
   auto& ms = GetSettings(settings);
 
   const float* ibuf = inBlock[0];
   float* obuf = outBlock[0];
   double frequency, omega, sn, cs, alpha;
   double in, out;
 
   data.lfoskip = ms.mFreq * 2 * M_PI / data.samplerate;
   data.depth = ms.mDepth / 100.0;
   data.freqofs = ms.mFreqOfs / 100.0;
 
   data.phase = ms.mPhase * M_PI / 180.0;
   data.outgain = DB_TO_LINEAR(ms.mOutGain);
 
   for (decltype(blockLen) i = 0; i < blockLen; i++)
   {
      in = (double)ibuf[i];
 
      if ((data.skipcount++) % lfoskipsamples == 0)
      {
         frequency = (1 + cos(data.skipcount * data.lfoskip + data.phase)) / 2;
         frequency = frequency * data.depth * (1 - data.freqofs) + data.freqofs;
         frequency = exp((frequency - 1) * 6);
         omega = M_PI * frequency;
         sn = sin(omega);
         cs = cos(omega);
         alpha = sn / (2 * ms.mRes);
         data.b0 = (1 - cs) / 2;
         data.b1 = 1 - cs;
         data.b2 = (1 - cs) / 2;
         data.a0 = 1 + alpha;
         data.a1 = -2 * cs;
         data.a2 = 1 - alpha;
      };
      out = (data.b0 * in + data.b1 * data.xn1 + data.b2 * data.xn2 -
             data.a1 * data.yn1 - data.a2 * data.yn2) /
            data.a0;
      data.xn2 = data.xn1;
      data.xn1 = in;
      data.yn2 = data.yn1;
      data.yn1 = out;
      out *= data.outgain;
 
      obuf[i] = (float)out;
   }
 
   return blockLen;
}
 
unsigned WahWahBase::Instance::GetAudioOutCount() const
{
   return 1;
}
 
unsigned WahWahBase::Instance::GetAudioInCount() const
{
   return 1;
}