LoopingPlaybackPolicy Class Reference

#include <PlaybackSchedule.h>

Inheritance diagram for LoopingPlaybackPolicy:

Collaboration diagram for LoopingPlaybackPolicy:

Public Member Functions
	~LoopingPlaybackPolicy () override
BufferTimes	SuggestedBufferTimes (PlaybackSchedule &schedule) override
	Provide hints for construction of playback RingBuffer objects. More...
bool	Done (PlaybackSchedule &schedule, unsigned long) override
	Returns true if schedule.GetTrackTime() has reached the end of playback. More...
PlaybackSlice	GetPlaybackSlice (PlaybackSchedule &schedule, size_t available) override
	Choose length of one fetch of samples from tracks in a call to AudioIO::FillPlayBuffers. More...
std::pair< double, double >	AdvancedTrackTime (PlaybackSchedule &schedule, double trackTime, size_t nSamples) override
	Compute a new point in a track's timeline from an old point and a real duration. More...
void	MessageConsumer (PlaybackSchedule &schedule) override
	May be called between AdvancedTrackTime() and RepositionPlayback() More...
bool	RepositionPlayback (PlaybackSchedule &schedule, const Mixers &playbackMixers, size_t frames, size_t available) override
	AudioIO::FillPlayBuffers calls this to update its cursors into tracks for changes of position or speed. More...
bool	Looping (const PlaybackSchedule &) const override
Public Member Functions inherited from PlaybackPolicy
virtual	~PlaybackPolicy ()=0
virtual void	Initialize (PlaybackSchedule &schedule, double rate)
	Called before starting an audio stream. More...
virtual void	Finalize (PlaybackSchedule &schedule)
	Called after stopping of an audio stream or an unsuccessful start. More...
virtual Mixer::WarpOptions	MixerWarpOptions (PlaybackSchedule &schedule)
	Options to use when constructing mixers for each playback track. More...
virtual bool	AllowSeek (PlaybackSchedule &schedule)
	Whether repositioning commands are allowed during playback. More...
virtual double	OffsetTrackTime (PlaybackSchedule &schedule, double offset)
	Called when the play head needs to jump a certain distance. More...
virtual std::chrono::milliseconds	SleepInterval (PlaybackSchedule &schedule)
	How long to wait between calls to AudioIO::TrackBufferExchange. More...

Private Attributes
size_t	mRemaining { 0 }
bool	mProgress { true }
bool	mKicked { false }

Additional Inherited Members
Public Types inherited from PlaybackPolicy
using	Mixers = std::vector< std::unique_ptr< Mixer > >
Protected Attributes inherited from PlaybackPolicy
double	mRate = 0

Detailed Description

Definition at line 451 of file PlaybackSchedule.h.

Constructor & Destructor Documentation

~LoopingPlaybackPolicy()

LoopingPlaybackPolicy::~LoopingPlaybackPolicy ( )

overridedefault

Member Function Documentation

AdvancedTrackTime()

std::pair< double, double > LoopingPlaybackPolicy::AdvancedTrackTime ( PlaybackSchedule &  schedule, double  trackTime, size_t  nSamples  )

overridevirtual

Compute a new point in a track's timeline from an old point and a real duration.

Needed because playback might be at non-unit speed.

Called one or more times between GetPlaybackSlice and RepositionPlayback, until the sum of the nSamples values equals the most recent playback slice (including any trailing silence).

Returns

a pair, which indicates a discontinuous jump when its members are not equal, or specially the end of playback when the second member is infinite

Reimplemented from PlaybackPolicy.

Definition at line 195 of file PlaybackSchedule.cpp.

{
   mRemaining -= std::min(mRemaining, nSamples);
   if ( mRemaining == 0 )
      // Wrap to start
      return { schedule.mT1, schedule.mT0 };
 
   // Defense against cases that might cause loops not to terminate
   if ( fabs(schedule.mT0 - schedule.mT1) < 1e-9 )
      return {schedule.mT0, schedule.mT0};
 
   auto realDuration = nSamples / mRate;
   if (schedule.ReversedTime())
      realDuration *= -1.0;
 
   if (schedule.mEnvelope)
      trackTime =
         schedule.SolveWarpedLength(trackTime, realDuration);
   else
      trackTime += realDuration;
 
   return { trackTime, trackTime };
}

References PlaybackSchedule::mEnvelope, min(), PlaybackPolicy::mRate, PlaybackSchedule::mT0, PlaybackSchedule::mT1, PlaybackSchedule::ReversedTime(), and PlaybackSchedule::SolveWarpedLength().

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Done()

bool LoopingPlaybackPolicy::Done ( PlaybackSchedule &  schedule, unsigned long  outputFrames  )

overridevirtual

Returns true if schedule.GetTrackTime() has reached the end of playback.

Parameters

outputFrames

how many playback frames were taken from RingBuffers

Reimplemented from PlaybackPolicy.

Definition at line 160 of file PlaybackSchedule.cpp.

{
   return false;
}

GetPlaybackSlice()

PlaybackSlice LoopingPlaybackPolicy::GetPlaybackSlice ( PlaybackSchedule &  schedule, size_t  available  )

overridevirtual

Choose length of one fetch of samples from tracks in a call to AudioIO::FillPlayBuffers.

Parameters

available

upper bound for the length of the fetch

Reimplemented from PlaybackPolicy.

Definition at line 166 of file PlaybackSchedule.cpp.

{
   // How many samples to produce for each channel.
   const auto realTimeRemaining = std::max(0.0, schedule.RealTimeRemaining());
   auto frames = available;
   auto toProduce = frames;
   double deltat = frames / mRate;
 
   mRemaining = realTimeRemaining * mRate;
   if (deltat > realTimeRemaining)
   {
      toProduce = frames = mRemaining;
      schedule.RealTimeAdvance( realTimeRemaining );
   }
   else
      schedule.RealTimeAdvance( deltat );
 
   // Don't fall into an infinite loop, if loop-playing a selection
   // that is so short, it has no samples: detect that case
   if (frames == 0) {
      bool progress = (schedule.mWarpedTime != 0.0);
      if (!progress)
         // Cause FillPlayBuffers to make progress, filling all available with 0
         frames = available, toProduce = 0;
   }
   return { available, frames, toProduce };
}

References PlaybackPolicy::mRate, PlaybackSchedule::mWarpedTime, PlaybackSchedule::RealTimeAdvance(), and PlaybackSchedule::RealTimeRemaining().

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Looping()

bool LoopingPlaybackPolicy::Looping ( const PlaybackSchedule &  schedule ) const

overridevirtual

be removed

Reimplemented from PlaybackPolicy.

Definition at line 273 of file PlaybackSchedule.cpp.

{
   return true;
}

MessageConsumer()

void LoopingPlaybackPolicy::MessageConsumer ( PlaybackSchedule &  schedule )

overridevirtual

May be called between AdvancedTrackTime() and RepositionPlayback()

Receive notifications from the main thread of changes of parameters affecting the policy

Default implementation ignores all messages

Reimplemented from PlaybackPolicy.

Definition at line 220 of file PlaybackSchedule.cpp.

{
   // This executes in the TrackBufferExchange thread
   auto data = schedule.mMessageChannel.Read();
   if (data.mT0 >= data.mT1)
      // Ignore empty region
      return;
 
   auto mine = std::tie(schedule.mT0, schedule.mT1);
   auto theirs = std::tie(data.mT0, data.mT1);
   if (mine != theirs) {
      mine = theirs;
      schedule.mWarpedLength = schedule.RealDuration(schedule.mT1);
      auto newTime = std::clamp(
         schedule.mTimeQueue.GetLastTime(), schedule.mT0, schedule.mT1);
      if (newTime == schedule.mT1)
         newTime = schedule.mT0;
 
      // So that the play head will redraw in the right place:
      schedule.mTimeQueue.SetLastTime(newTime);
 
      // Setup for the next visit to RepositionPlayback:
      schedule.RealTimeInit(newTime);
      const auto realTimeRemaining = std::max(0.0, schedule.RealTimeRemaining());
      mRemaining = realTimeRemaining * mRate;
      mKicked = true;
   }
}

References PlaybackSchedule::TimeQueue::GetLastTime(), PlaybackSchedule::mMessageChannel, PlaybackPolicy::mRate, PlaybackSchedule::mT0, PlaybackSchedule::mT1, PlaybackSchedule::mTimeQueue, PlaybackSchedule::mWarpedLength, PlaybackSchedule::RealDuration(), PlaybackSchedule::RealTimeInit(), PlaybackSchedule::RealTimeRemaining(), and PlaybackSchedule::TimeQueue::SetLastTime().

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RepositionPlayback()

bool LoopingPlaybackPolicy::RepositionPlayback ( PlaybackSchedule &  schedule, const Mixers &  playbackMixers, size_t  frames, size_t  available  )

overridevirtual

AudioIO::FillPlayBuffers calls this to update its cursors into tracks for changes of position or speed.

Returns

if true, AudioIO::FillPlayBuffers stops producing samples even if space remains

Parameters

frames	how many samples were just now buffered for play
available	how many more samples may be buffered

Reimplemented from PlaybackPolicy.

Definition at line 249 of file PlaybackSchedule.cpp.

{
   // msmeyer: If playing looped, check if we are at the end of the buffer
   // and if yes, restart from the beginning.
   if (mRemaining <= 0)
   {
      for (auto &pMixer : playbackMixers)
         pMixer->SetTimesAndSpeed( schedule.mT0, schedule.mT1, 1.0, mKicked );
      schedule.RealTimeRestart();
   }
   else if (mKicked)
   {
      const auto time = schedule.mTimeQueue.GetLastTime();
      for (auto &pMixer : playbackMixers) {
         // So that the mixer will fetch the next samples from the right place:
         pMixer->SetTimesAndSpeed( schedule.mT0, schedule.mT1, 1.0 );
         pMixer->Reposition(time, true);
      }
   }
   mKicked = false; // Ow!  Stop it!  Mo-o-o-om!
   return false;
}

References PlaybackSchedule::TimeQueue::GetLastTime(), PlaybackSchedule::mT0, PlaybackSchedule::mT1, PlaybackSchedule::mTimeQueue, and PlaybackSchedule::RealTimeRestart().

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SuggestedBufferTimes()

PlaybackPolicy::BufferTimes LoopingPlaybackPolicy::SuggestedBufferTimes ( PlaybackSchedule &  schedule )

overridevirtual

Provide hints for construction of playback RingBuffer objects.

Reimplemented from PlaybackPolicy.

Definition at line 153 of file PlaybackSchedule.cpp.

{
   // Shorter times than in the default policy so that responses to changes of
   // selection don't lag too much
   return { 0.5, 0.5, 1.0 };
}

Member Data Documentation

mKicked

bool LoopingPlaybackPolicy::mKicked { false }

private

Definition at line 476 of file PlaybackSchedule.h.

mProgress

bool LoopingPlaybackPolicy::mProgress { true }

private

Definition at line 475 of file PlaybackSchedule.h.

mRemaining

size_t LoopingPlaybackPolicy::mRemaining { 0 }

private

Definition at line 474 of file PlaybackSchedule.h.

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The documentation for this class was generated from the following files:

• PlaybackSchedule.h
• PlaybackSchedule.cpp