Public Member Functions | List of all members
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...

Inheritance 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 setNumberOfChannelsToProduce (int requiredNumberOfChannels)
 Specifies a number of channels that this audio source must produce from its getNextAudioBlock() callback. More...
 
void clearAllMappings ()
 Clears any mapped channels. More...
 
void setInputChannelMapping (int destChannelIndex, int sourceChannelIndex)
 Creates an input channel mapping. More...
 
void setOutputChannelMapping (int sourceChannelIndex, int destChannelIndex)
 Creates an output channel mapping. 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...
 
XmlElementcreateXml () const
 Returns an XML object to encapsulate the state of the mappings. More...
 
void restoreFromXml (const XmlElement &)
 Restores the mappings from an XML object created by createXML(). 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 getNextAudioBlock (const AudioSourceChannelInfo &) override
 Called repeatedly to fetch subsequent blocks of audio data. More...
 
- Public Member Functions inherited from AudioSource
virtual ~AudioSource ()
 Destructor. More...
 

Additional Inherited Members

- Protected Member Functions inherited from AudioSource
 AudioSource () noexcept
 Creates an AudioSource. More...
 

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
sourcethe input source to use. Make sure that this doesn't get deleted before the ChannelRemappingAudioSource object
deleteSourceWhenDeletedif 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

◆ setNumberOfChannelsToProduce()

void ChannelRemappingAudioSource::setNumberOfChannelsToProduce ( int  requiredNumberOfChannels)

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

◆ 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().

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

◆ 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.

◆ createXml()

XmlElement* ChannelRemappingAudioSource::createXml ( ) const

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

See also
restoreFromXml

◆ restoreFromXml()

void ChannelRemappingAudioSource::restoreFromXml ( const XmlElement )

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

See also
createXml

◆ 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
samplesPerBlockExpectedthe 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.
sampleRatethe 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.

◆ 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.


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