juce::ResamplingAudioSource Class Reference

A type of AudioSource that takes an input source and changes its sample rate. More...

#include <juce_ResamplingAudioSource.h>

Inheritance diagram for juce::ResamplingAudioSource:

Collaboration diagram for juce::ResamplingAudioSource:

Classes
struct	FilterState

Public Member Functions
	ResamplingAudioSource (AudioSource *inputSource, bool deleteInputWhenDeleted, int numChannels=2)
	Creates a ResamplingAudioSource for a given input source. More...
	~ResamplingAudioSource () override
	Destructor. More...
void	flushBuffers ()
	Clears any buffers and filters that the resampler is using. More...
void	getNextAudioBlock (const AudioSourceChannelInfo &) override
	Called repeatedly to fetch subsequent blocks of audio data. More...
double	getResamplingRatio () const noexcept
	Returns the current resampling ratio. More...
void	prepareToPlay (int samplesPerBlockExpected, double sampleRate) override
	Tells the source to prepare for playing. More...
void	releaseResources () override
	Allows the source to release anything it no longer needs after playback has stopped. More...
void	setResamplingRatio (double samplesInPerOutputSample)
	Changes the resampling ratio. More...

Private Member Functions
void	applyFilter (float *samples, int num, FilterState &fs)
void	createLowPass (double proportionalRate)
void	resetFilters ()
void	setFilterCoefficients (double c1, double c2, double c3, double c4, double c5, double c6)

Private Attributes
AudioBuffer< float >	buffer
int	bufferPos = 0
CriticalSection	callbackLock
double	coefficients [6]
HeapBlock< float * >	destBuffers
HeapBlock< FilterState >	filterStates
OptionalScopedPointer< AudioSource >	input
double	lastRatio = 1.0
const int	numChannels
double	ratio = 1.0
SpinLock	ratioLock
int	sampsInBuffer = 0
HeapBlock< const float * >	srcBuffers
double	subSampleOffset = 0.0

Detailed Description

A type of AudioSource that takes an input source and changes its sample rate.

See also

AudioSource, LagrangeInterpolator, CatmullRomInterpolator

@tags{Audio}

Constructor & Destructor Documentation

ResamplingAudioSource()

juce::ResamplingAudioSource::ResamplingAudioSource	(	AudioSource *	inputSource,
		bool	deleteInputWhenDeleted,
		int	numChannels = 2
	)

Creates a ResamplingAudioSource for a given input source.

Parameters

inputSource	the input source to read from
deleteInputWhenDeleted	if true, the input source will be deleted when this object is deleted
numChannels	the number of channels to process

~ResamplingAudioSource()

juce::ResamplingAudioSource::~ResamplingAudioSource ( )

override

Destructor.

Member Function Documentation

applyFilter()

void juce::ResamplingAudioSource::applyFilter ( float *  samples, int  num, FilterState &  fs  )

private

createLowPass()

void juce::ResamplingAudioSource::createLowPass ( double  proportionalRate )

private

flushBuffers()

void juce::ResamplingAudioSource::flushBuffers

(

)

Clears any buffers and filters that the resampler is using.

getNextAudioBlock()

void juce::ResamplingAudioSource::getNextAudioBlock ( const AudioSourceChannelInfo &  bufferToFill )

overridevirtual

Called repeatedly to fetch subsequent blocks of audio data.

After calling the prepareToPlay() method, this callback will be made each time the audio playback hardware (or whatever other destination the audio data is going to) needs another block of data.

It will generally be called on a high-priority system thread, or possibly even an interrupt, so be careful not to do too much work here, as that will cause audio glitches!

See also

AudioSourceChannelInfo, prepareToPlay, releaseResources

Implements juce::AudioSource.

getResamplingRatio()

double juce::ResamplingAudioSource::getResamplingRatio ( ) const

inlinenoexcept

Returns the current resampling ratio.

This is the value that was set by setResamplingRatio().

prepareToPlay()

void juce::ResamplingAudioSource::prepareToPlay ( int  samplesPerBlockExpected, double  sampleRate  )

overridevirtual

Tells the source to prepare for playing.

An AudioSource has two states: prepared and unprepared.

The prepareToPlay() method is guaranteed to be called at least once on an 'unprepared' source to put it into a 'prepared' state before any calls will be made to getNextAudioBlock(). This callback allows the source to initialise any resources it might need when playing.

Once playback has finished, the releaseResources() method is called to put the stream back into an 'unprepared' state.

Note that this method could be called more than once in succession without a matching call to releaseResources(), so make sure your code is robust and can handle that kind of situation.

Parameters

samplesPerBlockExpected	the number of samples that the source will be expected to supply each time its getNextAudioBlock() method is called. This number may vary slightly, because it will be dependent on audio hardware callbacks, and these aren't guaranteed to always use a constant block size, so the source should be able to cope with small variations.
sampleRate	the sample rate that the output will be used at - this is needed by sources such as tone generators.

See also

releaseResources, getNextAudioBlock

Implements juce::AudioSource.

releaseResources()

void juce::ResamplingAudioSource::releaseResources ( )

overridevirtual

Allows the source to release anything it no longer needs after playback has stopped.

This will be called when the source is no longer going to have its getNextAudioBlock() method called, so it should release any spare memory, etc. that it might have allocated during the prepareToPlay() call.

Note that there's no guarantee that prepareToPlay() will actually have been called before releaseResources(), and it may be called more than once in succession, so make sure your code is robust and doesn't make any assumptions about when it will be called.

See also

prepareToPlay, getNextAudioBlock

Implements juce::AudioSource.

resetFilters()

void juce::ResamplingAudioSource::resetFilters ( )

private

setFilterCoefficients()

void juce::ResamplingAudioSource::setFilterCoefficients ( double  c1, double  c2, double  c3, double  c4, double  c5, double  c6  )

private

setResamplingRatio()

void juce::ResamplingAudioSource::setResamplingRatio

(

double

samplesInPerOutputSample

)

Changes the resampling ratio.

(This value can be changed at any time, even while the source is running).

Parameters

samplesInPerOutputSample

if set to 1.0, the input is passed through; higher values will speed it up; lower values will slow it down. The ratio must be greater than 0

Member Data Documentation

buffer

AudioBuffer<float> juce::ResamplingAudioSource::buffer

private

bufferPos

int juce::ResamplingAudioSource::bufferPos = 0

private

callbackLock

CriticalSection juce::ResamplingAudioSource::callbackLock

private

coefficients

double juce::ResamplingAudioSource::coefficients[6]

private

destBuffers

HeapBlock<float*> juce::ResamplingAudioSource::destBuffers

private

filterStates

HeapBlock<FilterState> juce::ResamplingAudioSource::filterStates

private

input

OptionalScopedPointer<AudioSource> juce::ResamplingAudioSource::input

private

lastRatio

double juce::ResamplingAudioSource::lastRatio = 1.0

private

numChannels

const int juce::ResamplingAudioSource::numChannels

private

ratio

double juce::ResamplingAudioSource::ratio = 1.0

private

ratioLock

SpinLock juce::ResamplingAudioSource::ratioLock

private

sampsInBuffer

int juce::ResamplingAudioSource::sampsInBuffer = 0

private

srcBuffers

HeapBlock<const float*> juce::ResamplingAudioSource::srcBuffers

private

subSampleOffset

double juce::ResamplingAudioSource::subSampleOffset = 0.0

private

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

• juce_ResamplingAudioSource.h