engine::ReadAheadTimeStretcher Class Reference

Wraps a TimeStretcher but keeps a larger internal input and output buffer and uses a background thread to try and process frames, reducing CPU cost on real-time threads. More...

#include <tracktion_ReadAheadTimeStretcher.h>

Public Member Functions
	ReadAheadTimeStretcher (int numBlocksToReadAhead)
	Creates a ReadAheadTimeStretcher that will attempt to process the desired number of blocks on a background thread.
	~ReadAheadTimeStretcher ()
	Destructor.
void	initialise (double sourceSampleRate, int samplesPerBlock, int numChannels, TimeStretcher::Mode, TimeStretcher::ElastiqueProOptions, bool realtime)
	Initialises the TimeStretcher ready to perform timestretching.
bool	isInitialised () const
	Returns true if this has been fully initialised.
void	reset ()
	Resets the TimeStretcher ready for a new set of audio data, maintains mode, speed and pitch ratios.
bool	setSpeedAndPitch (float speedRatio, float semitones)
	Sets the timestretch speed ratio and semitones pitch shift.
int	getMaxFramesNeeded () const
	Returns the maximum number of frames that will ever be returned by getFramesNeeded.
int	getFramesNeeded () const
	Returns the expected number of frames required to generate some output.
int	getFramesRecomended () const
	Returns the number of frames that should be pushed to ensure the background thread has ample to work with.
bool	requiresMoreFrames () const
	Returns true if more frames are required to be pushed in order for a pop operation to succeed.
int	getFreeSpace () const
	Returns the number of samples that can be pushed to the input, ready to be processed.
int	pushData (const float *const *inChannels, int numSamples)
	Pushes a number of samples to the instance ready to be time-stretched.
int	getNumReady () const
	Returns the number of samples ready in the output buffer which can be retrieved without processing the time-stretch.
int	popData (float *const *outChannels, int numSamples)
	Retrieves some samples from the output buffer.
int	flush (float *const *outChannels)
	Flushes the end of the stream when input data is exhausted but there is still output data available.

Detailed Description

Wraps a TimeStretcher but keeps a larger internal input and output buffer and uses a background thread to try and process frames, reducing CPU cost on real-time threads.

Constructor & Destructor Documentation

ReadAheadTimeStretcher()

engine::ReadAheadTimeStretcher::ReadAheadTimeStretcher

(

int

numBlocksToReadAhead

)

Creates a ReadAheadTimeStretcher that will attempt to process the desired number of blocks on a background thread.

The number of blocks is a multiple of that passed to the initalise call.

~ReadAheadTimeStretcher()

engine::ReadAheadTimeStretcher::~ReadAheadTimeStretcher

(

)

Destructor.

Member Function Documentation

initialise()

void engine::ReadAheadTimeStretcher::initialise	(	double	sourceSampleRate,
		int	samplesPerBlock,
		int	numChannels,
		TimeStretcher::Mode	,
		TimeStretcher::ElastiqueProOptions	,
		bool	realtime
	)

Initialises the TimeStretcher ready to perform timestretching.

This must be called at least once before calling the processData methods.

Parameters

sourceSampleRate	The sample rate this will be processed at
samplesPerBlock	The expected number of samples per process block
numChannels	The number of channels to process
Mode	The Mode to enable
ElastiqueProOptions	The Elastique options to use, ignored in non-ElastiquePro modes
realtime	Indicates this is for real-time or offline use

isInitialised()

bool engine::ReadAheadTimeStretcher::isInitialised

(

)

const

Returns true if this has been fully initialised.

reset()

void engine::ReadAheadTimeStretcher::reset

(

)

Resets the TimeStretcher ready for a new set of audio data, maintains mode, speed and pitch ratios.

setSpeedAndPitch()

bool engine::ReadAheadTimeStretcher::setSpeedAndPitch	(	float	speedRatio,
		float	semitones
	)

Sets the timestretch speed ratio and semitones pitch shift.

Parameters

speedRatio	The ratio for timestretched speed. 1 = no stretching, 2 = half as fast, 0.5 = twice as fast etc.
semitones	The number of semitones to adjust the pitch by 0 = not shift, 12 = up one oct, -12 = down one oct etc.

getMaxFramesNeeded()

int engine::ReadAheadTimeStretcher::getMaxFramesNeeded

(

)

const

Returns the maximum number of frames that will ever be returned by getFramesNeeded.

This can be used to size FIFOs for real-time use accordingly.

getFramesNeeded()

int engine::ReadAheadTimeStretcher::getFramesNeeded

(

)

const

Returns the expected number of frames required to generate some output.

This should be queried each block and the returned number of frames be passed to pushData.

getFramesRecomended()

int engine::ReadAheadTimeStretcher::getFramesRecomended

(

)

const

Returns the number of frames that should be pushed to ensure the background thread has ample to work with.

This also prioritises a fast startup where possible after a reset()

requiresMoreFrames()

bool engine::ReadAheadTimeStretcher::requiresMoreFrames

(

)

const

Returns true if more frames are required to be pushed in order for a pop operation to succeed.

getFreeSpace()

int engine::ReadAheadTimeStretcher::getFreeSpace

(

)

const

Returns the number of samples that can be pushed to the input, ready to be processed.

pushData()

int engine::ReadAheadTimeStretcher::pushData	(	const float *const *	inChannels,
		int	numSamples
	)

Pushes a number of samples to the instance ready to be time-stretched.

N.B. This doesn't actually do any processing so should be quick.

Returns

The number of samples read

getNumReady()

int engine::ReadAheadTimeStretcher::getNumReady

(

)

const

Returns the number of samples ready in the output buffer which can be retrieved without processing the time-stretch.

popData()

int engine::ReadAheadTimeStretcher::popData	(	float *const *	outChannels,
		int	numSamples
	)

Retrieves some samples from the output buffer.

N.B. If there aren't enough samples already processed this will do the processing so its cost can vary.

Returns

The number of samples read

flush()

int engine::ReadAheadTimeStretcher::flush

(

float *const *

outChannels

)

Flushes the end of the stream when input data is exhausted but there is still output data available.

Once you have called this, you can no longer call processData.

Parameters

outChannels

The destination for non-interleaved output samples. This should be as big as samplesPerBlock passed to the constructor but it may not fill the whole buffer. In cases where less than samplesPerBlock is returned, you should query getFramesNeeded and call this method again, incrementing destination buffers as required.

Returns

The number of frames read and hence written to outChannels

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

• tracktion_ReadAheadTimeStretcher.h