Method Process

libraries/lib-builtin-effects/AutoDuckBase.cpp:157–332

}

bool AutoDuckBase::Process(EffectInstance&, EffectSettings&)
{
   if (GetNumWaveTracks() == 0 || !mControlTrack)
      return false;

   bool cancel = false;

   auto start = mControlTrack->TimeToLongSamples(mT0 + mOuterFadeDownLen);
   auto end = mControlTrack->TimeToLongSamples(mT1 - mOuterFadeUpLen);

   if (end <= start)
      return false;

   WaveTrack::Holder pFirstTrack;
   auto pControlTrack = mControlTrack;
   // If there is any stretch in the control track, substitute a temporary
   // rendering before trying to use GetFloats
   {
      const auto t0 = pControlTrack->LongSamplesToTime(start);
      const auto t1 = pControlTrack->LongSamplesToTime(end);
      if (TimeStretching::HasPitchOrSpeed(*pControlTrack, t0, t1))
      {
         pFirstTrack = pControlTrack->Duplicate()->SharedPointer<WaveTrack>();
         if (pFirstTrack)
         {
            UserException::WithCancellableProgress(
               [&](const ProgressReporter& reportProgress) {
                  pFirstTrack->ApplyPitchAndSpeed(
                     { { t0, t1 } }, reportProgress);
               },
               TimeStretching::defaultStretchRenderingTitle,
               XO("Rendering Control-Track Time-Stretched Audio"));
            pControlTrack = pFirstTrack.get();
         }
      }
   }

   // the minimum number of samples we have to wait until the maximum
   // pause has been exceeded
   double maxPause = mMaximumPause;

   // We don't fade in until we have time enough to actually fade out again
   if (maxPause < mOuterFadeDownLen + mOuterFadeUpLen)
      maxPause = mOuterFadeDownLen + mOuterFadeUpLen;

   auto minSamplesPause = pControlTrack->TimeToLongSamples(maxPause);

   double threshold = DB_TO_LINEAR(mThresholdDb);

   // adjust the threshold so we can compare it to the rmsSum value
   threshold = threshold * threshold * kRMSWindowSize;

   int rmsPos = 0;
   double rmsSum = 0;
   // to make the progress bar appear more natural, we first look for all
   // duck regions and apply them all at once afterwards
   std::vector<AutoDuckRegion> regions;
   bool inDuckRegion = false;