DownmixSource.cpp

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/**********************************************************************
 
  Audacity: A Digital Audio Editor
 
  DownmixSource.cpp
 
  Dominic Mazzoni
  Markus Meyer
  Vaughan Johnson
 
*******************************************************************/
 
 
#include "DownmixSource.h"
 
#include "AudioGraphChannel.h"
#include "WideSampleSequence.h"
 
SequenceDownmixSource::SequenceDownmixSource(AudioGraph::Source& downstream,
                                             const WideSampleSequence& sequence,
                                             const ArrayOf<bool> *channelMap)
   : mDownstream(downstream)
   , mSequence(sequence)
   , mpMap(channelMap)
{
}
 
AudioGraph::Source& SequenceDownmixSource::GetDownstream() const
{
   return mDownstream;
}
 
size_t SequenceDownmixSource::NChannels() const
{
   return mSequence.NChannels();
}
 
float SequenceDownmixSource::GetChannelGain(size_t channel) const
{
   return mSequence.GetChannelVolume(channel);
}
 
void SequenceDownmixSource::FindChannelFlags(unsigned char *channelFlags, size_t numChannels, size_t iChannel)
{
   const bool* map = mpMap ? mpMap[iChannel].get() : nullptr;
   const auto end = channelFlags + numChannels;
   std::fill(channelFlags, end, 0);
   if (map)
      // ignore left and right when downmixing is customized
      std::copy(map, map + numChannels, channelFlags);
   else if (AudioGraph::IsMono(mSequence))
      std::fill(channelFlags, end, 1);
   else if (iChannel == 0)
      channelFlags[0] = 1;
   else if (iChannel == 1) {
      if (numChannels >= 2)
         channelFlags[1] = 1;
      else
         channelFlags[0] = 1;
   }
}
bool SequenceDownmixSource::CanMakeMono() const
{
   return mpMap == nullptr;
}
 
SimpleDonwmixSource::SimpleDonwmixSource(AudioGraph::Source& downstream, size_t channels)
   : mDownstream(downstream), mNChannels(channels)
{
}
 
AudioGraph::Source& SimpleDonwmixSource::GetDownstream() const
{
   return mDownstream;
}
 
size_t SimpleDonwmixSource::NChannels() const
{
   return mNChannels;
}
 
float SimpleDonwmixSource::GetChannelGain(size_t) const
{
   return 1.0f;
}
 
void SimpleDonwmixSource::FindChannelFlags(unsigned char* channelFlags, size_t numChannels, size_t iChannel)
{
   if(mNChannels == 1)
   {
      for(size_t i = 0; i < numChannels; ++i)
         channelFlags[i] = true;
   }
   else
   {
      for(size_t i = 0; i < numChannels; ++i)
         channelFlags[i] = i == iChannel;
   }
}
 
bool SimpleDonwmixSource::CanMakeMono() const
{
   return true;
}