ChannelRemappingAudioSource Class Reference

An AudioSource that takes the audio from another source, and re-maps its input and output channels to a different arrangement. More...

#include <juce_ChannelRemappingAudioSource.h>

Inheritance diagram for ChannelRemappingAudioSource:

Collaboration diagram for ChannelRemappingAudioSource:

Public Member Functions
	ChannelRemappingAudioSource (AudioSource *source, bool deleteSourceWhenDeleted)
	Creates a remapping source that will pass on audio from the given input. More...
	~ChannelRemappingAudioSource ()
	Destructor. More...
void	clearAllMappings ()
	Clears any mapped channels. More...
XmlElement *	createXml () const
	Returns an XML object to encapsulate the state of the mappings. More...
void	getNextAudioBlock (const AudioSourceChannelInfo &) override
	Called repeatedly to fetch subsequent blocks of audio data. More...
int	getRemappedInputChannel (int inputChannelIndex) const
	Returns the channel from our input that will be sent to channel inputChannelIndex of our input audio source. More...
int	getRemappedOutputChannel (int outputChannelIndex) const
	Returns the output channel to which channel outputChannelIndex of our input audio source will be sent to. 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	restoreFromXml (const XmlElement &)
	Restores the mappings from an XML object created by createXML(). More...
void	setInputChannelMapping (int destChannelIndex, int sourceChannelIndex)
	Creates an input channel mapping. More...
void	setNumberOfChannelsToProduce (int requiredNumberOfChannels)
	Specifies a number of channels that this audio source must produce from its getNextAudioBlock() callback. More...
void	setOutputChannelMapping (int sourceChannelIndex, int destChannelIndex)
	Creates an output channel mapping. More...

Private Attributes
AudioSampleBuffer	buffer
CriticalSection	lock
AudioSourceChannelInfo	remappedInfo
Array< int >	remappedInputs
Array< int >	remappedOutputs
int	requiredNumberOfChannels
OptionalScopedPointer< AudioSource >	source

Detailed Description

An AudioSource that takes the audio from another source, and re-maps its input and output channels to a different arrangement.

You can use this to increase or decrease the number of channels that an audio source uses, or to re-order those channels.

Call the reset() method before using it to set up a default mapping, and then the setInputChannelMapping() and setOutputChannelMapping() methods to create an appropriate mapping, otherwise no channels will be connected and it'll produce silence.

See also

AudioSource

Constructor & Destructor Documentation

ChannelRemappingAudioSource()

ChannelRemappingAudioSource::ChannelRemappingAudioSource	(	AudioSource *	source,
		bool	deleteSourceWhenDeleted
	)

Creates a remapping source that will pass on audio from the given input.

Parameters

source	the input source to use. Make sure that this doesn't get deleted before the ChannelRemappingAudioSource object
deleteSourceWhenDeleted	if true, the input source will be deleted when this object is deleted, if false, the caller is responsible for its deletion

~ChannelRemappingAudioSource()

ChannelRemappingAudioSource::~ChannelRemappingAudioSource

(

)

Destructor.

Member Function Documentation

clearAllMappings()

void ChannelRemappingAudioSource::clearAllMappings

(

)

Clears any mapped channels.

After this, no channels are mapped, so this object will produce silence. Create some mappings with setInputChannelMapping() and setOutputChannelMapping().

createXml()

XmlElement* ChannelRemappingAudioSource::createXml

(

)

const

Returns an XML object to encapsulate the state of the mappings.

See also

restoreFromXml

getNextAudioBlock()

void ChannelRemappingAudioSource::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 AudioSource.

getRemappedInputChannel()

int ChannelRemappingAudioSource::getRemappedInputChannel

(

int

inputChannelIndex

)

const

Returns the channel from our input that will be sent to channel inputChannelIndex of our input audio source.

getRemappedOutputChannel()

int ChannelRemappingAudioSource::getRemappedOutputChannel

(

int

outputChannelIndex

)

const

Returns the output channel to which channel outputChannelIndex of our input audio source will be sent to.

prepareToPlay()

void ChannelRemappingAudioSource::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 'unpreprared' 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 AudioSource.

releaseResources()

void ChannelRemappingAudioSource::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 AudioSource.

restoreFromXml()

void ChannelRemappingAudioSource::restoreFromXml

(

const XmlElement &

)

Restores the mappings from an XML object created by createXML().

See also

createXml

setInputChannelMapping()

void ChannelRemappingAudioSource::setInputChannelMapping	(	int	destChannelIndex,
		int	sourceChannelIndex
	)

Creates an input channel mapping.

When the getNextAudioBlock() method is called, the data in channel sourceChannelIndex of the incoming data will be sent to destChannelIndex of our input source.

Parameters

destChannelIndex	the index of an input channel in our input audio source (i.e. the source specified when this object was created).
sourceChannelIndex	the index of the input channel in the incoming audio data buffer during our getNextAudioBlock() callback

setNumberOfChannelsToProduce()

void ChannelRemappingAudioSource::setNumberOfChannelsToProduce

(

int

requiredNumberOfChannels

)

Specifies a number of channels that this audio source must produce from its getNextAudioBlock() callback.

setOutputChannelMapping()

void ChannelRemappingAudioSource::setOutputChannelMapping	(	int	sourceChannelIndex,
		int	destChannelIndex
	)

Creates an output channel mapping.

When the getNextAudioBlock() method is called, the data returned in channel sourceChannelIndex by our input audio source will be copied to channel destChannelIndex of the final buffer.

Parameters

sourceChannelIndex	the index of an output channel coming from our input audio source (i.e. the source specified when this object was created).
destChannelIndex	the index of the output channel in the incoming audio data buffer during our getNextAudioBlock() callback

Member Data Documentation

buffer

AudioSampleBuffer ChannelRemappingAudioSource::buffer

private

lock

CriticalSection ChannelRemappingAudioSource::lock

private

remappedInfo

AudioSourceChannelInfo ChannelRemappingAudioSource::remappedInfo

private

remappedInputs

Array<int> ChannelRemappingAudioSource::remappedInputs

private

remappedOutputs

Array<int> ChannelRemappingAudioSource::remappedOutputs

private

requiredNumberOfChannels

int ChannelRemappingAudioSource::requiredNumberOfChannels

private

source

OptionalScopedPointer<AudioSource> ChannelRemappingAudioSource::source

private

---

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

• juce_ChannelRemappingAudioSource.h