ClipSegment.cpp

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/*  SPDX-License-Identifier: GPL-2.0-or-later */
/*!********************************************************************
 
  Audacity: A Digital Audio Editor
 
  ClipSegment.cpp
 
  Matthieu Hodgkinson
 
**********************************************************************/
#include "ClipSegment.h"
#include "ClipInterface.h"
#include "SampleFormat.h"
#include "StaffPadTimeAndPitch.h"
#include <cassert>
#include <cmath>
#include <functional>
 
namespace
{
TimeAndPitchInterface::Parameters
GetStretchingParameters(const ClipInterface& clip)
{
   TimeAndPitchInterface::Parameters params;
   params.timeRatio = clip.GetStretchRatio();
   params.pitchRatio = std::pow(2., clip.GetCentShift() / 1200.);
   params.preserveFormants =
      clip.GetPitchAndSpeedPreset() == PitchAndSpeedPreset::OptimizeForVoice;
   return params;
}
 
sampleCount
GetTotalNumSamplesToProduce(const ClipInterface& clip, double durationToDiscard)
{
   return sampleCount { clip.GetVisibleSampleCount().as_double() *
                           clip.GetStretchRatio() -
                        durationToDiscard * clip.GetRate() + .5 };
}
} // namespace
 
ClipSegment::ClipSegment(
   const ClipInterface& clip, double durationToDiscard,
   PlaybackDirection direction)
    : mTotalNumSamplesToProduce { GetTotalNumSamplesToProduce(
         clip, durationToDiscard) }
    , mSource { clip, durationToDiscard, direction }
    , mPreserveFormants { clip.GetPitchAndSpeedPreset() ==
                          PitchAndSpeedPreset::OptimizeForVoice }
    , mCentShift { clip.GetCentShift() }
    , mStretcher { std::make_unique<StaffPadTimeAndPitch>(
         clip.GetRate(), clip.NChannels(), mSource,
         GetStretchingParameters(clip)) }
    , mOnSemitoneShiftChangeSubscription { clip.SubscribeToCentShiftChange(
         [this](int cents) {
            mCentShift = cents;
            mUpdateCentShift = true;
         }) }
    , mOnFormantPreservationChangeSubscription {
       clip.SubscribeToPitchAndSpeedPresetChange(
          [this](PitchAndSpeedPreset preset) {
             mPreserveFormants =
                preset == PitchAndSpeedPreset::OptimizeForVoice;
             mUpdateFormantPreservation = true;
          })
    }
{
}
 
ClipSegment::~ClipSegment()
{
   mOnSemitoneShiftChangeSubscription.Reset();
   mOnFormantPreservationChangeSubscription.Reset();
}
 
size_t ClipSegment::GetFloats(float* const* buffers, size_t numSamples)
{
   // Check if formant preservation of pitch shift needs to be updated.
   // This approach is not immune to a race condition, but it is unlikely and
   // not critical, as it would only affect one playback pass, during which the
   // user could easily correct the mistake if needed. On the other hand, we
   // cannot trust that the observer subscriptions do not get called after
   // destruction of this object, so better not do anything too sophisticated
   // there.
   if (mUpdateFormantPreservation.exchange(false))
      mStretcher->OnFormantPreservationChange(mPreserveFormants);
   if (mUpdateCentShift.exchange(false))
      mStretcher->OnCentShiftChange(mCentShift);
   const auto numSamplesToProduce = limitSampleBufferSize(
      numSamples, mTotalNumSamplesToProduce - mTotalNumSamplesProduced);
   mStretcher->GetSamples(buffers, numSamplesToProduce);
   mTotalNumSamplesProduced += numSamplesToProduce;
   return numSamplesToProduce;
}
 
bool ClipSegment::Empty() const
{
   return mTotalNumSamplesProduced == mTotalNumSamplesToProduce;
}
 
size_t ClipSegment::NChannels() const
{
   return mSource.NChannels();
}