SampleTrackSource Class Reference

Adapts SampleTrack to the interface AudioGraph::Source. More...

#include <SampleTrackSource.h>

Inheritance diagram for SampleTrackSource:

Collaboration diagram for SampleTrackSource:

Public Types
using	Poller = std::function< bool(sampleCount blockSize)>
	Type of function returning false if user cancels progress. More...
Public Types inherited from AudioGraph::Source
using	Buffers = AudioGraph::Buffers

Public Member Functions
	SampleTrackSource (const SampleTrack &left, const SampleTrack *pRight, sampleCount start, sampleCount len, Poller pollUser)
	~SampleTrackSource () override
bool	AcceptsBuffers (const Buffers &buffers) const override
bool	AcceptsBlockSize (size_t blockSize) const override
	Always true. More...
std::optional< size_t >	Acquire (Buffers &data, size_t bound) override
	Occupy vacant space in Buffers with some data. More...
sampleCount	Remaining () const override
	Result includes any amount Acquired and not yet Released. More...
bool	Release () override
	Can test for user cancellation. More...
Public Member Functions inherited from AudioGraph::Source
virtual	~Source ()
virtual bool	AcceptsBuffers (const Buffers &buffers) const =0
virtual bool	AcceptsBlockSize (size_t blockSize) const =0
virtual std::optional< size_t >	Acquire (Buffers &data, size_t bound)=0
	Occupy vacant space in Buffers with some data. More...
virtual sampleCount	Remaining () const =0
	Result includes any amount Acquired and not yet Released. More...
virtual bool	Release ()=0
	Caller is done examining last Acquire()d positions. More...
virtual bool	Terminates () const
	Needed only to make some postconditions assertable; defaults true. More...

Private Attributes
const SampleTrack &	mLeft
const SampleTrack *const	mpRight
const Poller	mPollUser
sampleCount	mPos {}
sampleCount	mOutputRemaining {}
size_t	mLastProduced {}
size_t	mFetched {}
bool	mInitialized { false }

Detailed Description

Adapts SampleTrack to the interface AudioGraph::Source.

Definition at line 25 of file SampleTrackSource.h.

Member Typedef Documentation

Poller

using SampleTrackSource::Poller = std::function<bool(sampleCount blockSize)>

Type of function returning false if user cancels progress.

Definition at line 28 of file SampleTrackSource.h.

Constructor & Destructor Documentation

SampleTrackSource()

SampleTrackSource::SampleTrackSource	(	const SampleTrack &	left,
		const SampleTrack *	pRight,
		sampleCount	start,
		sampleCount	len,
		Poller	pollUser
	)

Postcondition

Remaining() == len

Definition at line 27 of file SampleTrackSource.cpp.

   : mLeft{ left }, mpRight{ pRight }, mPollUser{ move(pollUser) }
   , mPos{ start }, mOutputRemaining{ len  }
{
}

~SampleTrackSource()

SampleTrackSource::~SampleTrackSource ( )

overridedefault

Member Function Documentation

AcceptsBlockSize()

bool SampleTrackSource::AcceptsBlockSize ( size_t  blockSize ) const

overridevirtual

Always true.

Implements AudioGraph::Source.

Definition at line 42 of file SampleTrackSource.cpp.

{
   return true;
}

Referenced by Acquire().

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AcceptsBuffers()

bool SampleTrackSource::AcceptsBuffers ( const Buffers &  buffers ) const

overridevirtual

If constructed with positive length, then accepts buffers only when number of channels is positive

Implements AudioGraph::Source.

Definition at line 37 of file SampleTrackSource.cpp.

{
   return mOutputRemaining == 0 || buffers.Channels() > 0;
}

References AudioGraph::Buffers::Channels(), and mOutputRemaining.

Referenced by Acquire().

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Acquire()

std::optional< size_t > SampleTrackSource::Acquire ( Buffers &  data, size_t  bound  )

overridevirtual

Occupy vacant space in Buffers with some data.

May exceeed a single block of production Can assume same buffer is passed each time, while the caller advances it over the previous production, or discards it, or rotates the buffer. May rewind or rotate the buffer.

Returns

number of positions available to read from data or nullopt to fail

Precondition

AcceptsBuffers(data)

AcceptsBlockSize(data.BlockSize())

bound <= data.BlockSize()

data.BlockSize() <= data.Remaining()

Postcondition

result: !result || *result <= bound

result: !result || *result <= data.Remaining()

result: !result || *result <= Remaining()

data.Remaining() > 0

result: !result || bound == 0 || Remaining() == 0 || *result > 0 (progress guarantee)

!Terminates() or Remaining() was not previously defined, or is unchanged

Implements AudioGraph::Source.

Definition at line 52 of file SampleTrackSource.cpp.

{
   assert(bound <= data.BlockSize());
   assert(data.BlockSize() <= data.Remaining());
   assert(AcceptsBuffers(data));
   assert(AcceptsBlockSize(data.BlockSize()));
 
   if (!mInitialized || mFetched < bound) {
      // Need to fill sufficent data in the buffers
      // Calculate the number of samples to get
      const auto fetch =
         limitSampleBufferSize(data.Remaining() - mFetched, Remaining());
      // guarantees write won't overflow
      assert(mFetched + fetch <= data.Remaining());
      // Fill the buffers
      mLeft.GetFloats(&data.GetWritePosition(0) + mFetched, mPos, fetch);
      if (mpRight && data.Channels() > 1)
         mpRight->GetFloats(&data.GetWritePosition(1) + mFetched, mPos, fetch);
      mPos += fetch;
      mFetched += fetch;
      mInitialized = true;
   }
   assert(data.Remaining() > 0);
   auto result = mLastProduced = std::min(bound,
      limitSampleBufferSize(data.Remaining(), Remaining()));
   // assert post
   assert(result <= bound);
   assert(result <= data.Remaining());
   assert(result <= Remaining());
   // true because the three terms of the min would be positive
   assert(bound == 0 || Remaining() == 0 || result > 0);
   return { result };
}

References AcceptsBlockSize(), AcceptsBuffers(), AudioGraph::Buffers::BlockSize(), AudioGraph::Buffers::Channels(), SampleTrack::GetFloats(), AudioGraph::Buffers::GetWritePosition(), limitSampleBufferSize(), mFetched, min(), mInitialized, mLastProduced, mLeft, mPos, mpRight, AudioGraph::Buffers::Remaining(), and Remaining().

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Release()

bool SampleTrackSource::Release ( )

overridevirtual

Can test for user cancellation.

Implements AudioGraph::Source.

Definition at line 86 of file SampleTrackSource.cpp.

{
   mOutputRemaining -= mLastProduced;
   mFetched -= mLastProduced;
   mLastProduced = 0;
   assert(mOutputRemaining >= 0);
   return !mPollUser || mPollUser(mPos);
}

References mFetched, mLastProduced, mOutputRemaining, mPollUser, and mPos.

Remaining()

sampleCount SampleTrackSource::Remaining ( ) const

overridevirtual

Result includes any amount Acquired and not yet Released.

May be undefined before the first successful call to Acquire()

Postcondition

result: result >= 0

Implements AudioGraph::Source.

Definition at line 47 of file SampleTrackSource.cpp.

{
   return std::max<sampleCount>(0, mOutputRemaining);
}

References mOutputRemaining.

Referenced by Acquire().

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Member Data Documentation

mFetched

size_t SampleTrackSource::mFetched {}

private

Definition at line 56 of file SampleTrackSource.h.

Referenced by Acquire(), and Release().

mInitialized

bool SampleTrackSource::mInitialized { false }

private

Definition at line 57 of file SampleTrackSource.h.

Referenced by Acquire().

mLastProduced

size_t SampleTrackSource::mLastProduced {}

private

Definition at line 55 of file SampleTrackSource.h.

Referenced by Acquire(), and Release().

mLeft

const SampleTrack& SampleTrackSource::mLeft

private

Definition at line 49 of file SampleTrackSource.h.

Referenced by Acquire().

mOutputRemaining

sampleCount SampleTrackSource::mOutputRemaining {}

private

Definition at line 54 of file SampleTrackSource.h.

Referenced by AcceptsBuffers(), Release(), and Remaining().

mPollUser

const Poller SampleTrackSource::mPollUser

private

Definition at line 51 of file SampleTrackSource.h.

Referenced by Release().

mPos

sampleCount SampleTrackSource::mPos {}

private

Definition at line 53 of file SampleTrackSource.h.

Referenced by Acquire(), and Release().

mpRight

const SampleTrack* const SampleTrackSource::mpRight

private

Definition at line 50 of file SampleTrackSource.h.

Referenced by Acquire().

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

• SampleTrackSource.h
• SampleTrackSource.cpp