AudioSegmentFactory.cpp

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/*  SPDX-License-Identifier: GPL-2.0-or-later */
/*!********************************************************************
 
  Audacity: A Digital Audio Editor
 
  AudioSegmentFactory.cpp
 
  Matthieu Hodgkinson
 
**********************************************************************/
 
#include "AudioSegmentFactory.h"
#include "ClipInterface.h"
#include "ClipSegment.h"
#include "SilenceSegment.h"
#include "TimeAndPitchInterface.h"
 
#include <algorithm>
 
using ClipConstHolder = std::shared_ptr<const ClipInterface>;
 
AudioSegmentFactory::AudioSegmentFactory(
   int sampleRate, int numChannels, ClipConstHolders clips)
    : mClips { std::move(clips) }
    , mSampleRate { sampleRate }
    , mNumChannels { numChannels }
{
}
 
std::vector<std::shared_ptr<AudioSegment>>
AudioSegmentFactory::CreateAudioSegmentSequence(
   double playbackStartTime, PlaybackDirection direction)
{
   return direction == PlaybackDirection::forward ?
             CreateAudioSegmentSequenceForward(playbackStartTime) :
             CreateAudioSegmentSequenceBackward(playbackStartTime);
}
 
std::vector<std::shared_ptr<AudioSegment>>
AudioSegmentFactory::CreateAudioSegmentSequenceForward(double t0)
{
   auto sortedClips = mClips;
   std::sort(
      sortedClips.begin(), sortedClips.end(),
      [](const std::shared_ptr<const ClipInterface>& a,
         const std::shared_ptr<const ClipInterface>& b) {
         return a->GetPlayStartTime() < b->GetPlayStartTime();
      });
   std::vector<std::shared_ptr<AudioSegment>> segments;
   for (const auto& clip : sortedClips)
   {
      if (clip->GetPlayStartTime() > t0)
      {
         const auto numSamples =
            sampleCount { (clip->GetPlayStartTime() - t0) * mSampleRate + .5 };
         segments.push_back(
            std::make_shared<SilenceSegment>(mNumChannels, numSamples));
         t0 = clip->GetPlayStartTime();
      }
      else if (clip->GetPlayEndTime() <= t0)
         continue;
      segments.push_back(std::make_shared<ClipSegment>(
         *clip, t0 - clip->GetPlayStartTime(), PlaybackDirection::forward));
      t0 = clip->GetPlayEndTime();
   }
   return segments;
}
 
std::vector<std::shared_ptr<AudioSegment>>
AudioSegmentFactory::CreateAudioSegmentSequenceBackward(double t0)
{
   auto sortedClips = mClips;
   std::sort(
      sortedClips.begin(), sortedClips.end(),
      [&](
         const std::shared_ptr<const ClipInterface>& a,
         const std::shared_ptr<const ClipInterface>& b) {
         return a->GetPlayEndTime() > b->GetPlayEndTime();
      });
   std::vector<std::shared_ptr<AudioSegment>> segments;
   for (const auto& clip : sortedClips)
   {
      if (clip->GetPlayEndTime() < t0)
      {
         const auto numSamples =
            sampleCount { (t0 - clip->GetPlayEndTime()) * mSampleRate + .5 };
         segments.push_back(
            std::make_shared<SilenceSegment>(mNumChannels, numSamples));
         t0 = clip->GetPlayEndTime();
      }
      else if (clip->GetPlayStartTime() >= t0)
         continue;
      segments.push_back(std::make_shared<ClipSegment>(
         *clip, clip->GetPlayEndTime() - t0, PlaybackDirection::backward));
      t0 = clip->GetPlayStartTime();
   }
   return segments;
}