AudioSource Class Reference

Base class for objects that can produce a continuous stream of audio. More...

Inherited by ChannelRemappingAudioSource, IIRFilterAudioSource, MixerAudioSource, PositionableAudioSource, ResamplingAudioSource, and ToneGeneratorAudioSource.

List of all members.

Public Member Functions

virtual ~AudioSource ()
 Destructor.
virtual void prepareToPlay (int samplesPerBlockExpected, double sampleRate)=0
 Tells the source to prepare for playing.
virtual void releaseResources ()=0
 Allows the source to release anything it no longer needs after playback has stopped.
virtual void getNextAudioBlock (const AudioSourceChannelInfo &bufferToFill)=0
 Called repeatedly to fetch subsequent blocks of audio data.

Protected Member Functions

 AudioSource () throw ()
 Creates an AudioSource.

Detailed Description

Base class for objects that can produce a continuous stream of audio.

See also:
AudioFormatReaderSource, ResamplingAudioSource

Constructor & Destructor Documentation

AudioSource::AudioSource (  )  throw () [protected]

Creates an AudioSource.

virtual AudioSource::~AudioSource (  )  [virtual]

Destructor.


Member Function Documentation

virtual void AudioSource::prepareToPlay ( int  samplesPerBlockExpected,
double  sampleRate 
) [pure virtual]

Tells the source to prepare for playing.

The source can use this opportunity to initialise anything it needs to.

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

Implemented in AudioFormatReaderSource, AudioTransportSource, BufferingAudioSource, ChannelRemappingAudioSource, IIRFilterAudioSource, MixerAudioSource, ResamplingAudioSource, and ToneGeneratorAudioSource.

virtual void AudioSource::releaseResources (  )  [pure virtual]

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

Implemented in AudioFormatReaderSource, AudioTransportSource, BufferingAudioSource, ChannelRemappingAudioSource, IIRFilterAudioSource, MixerAudioSource, ResamplingAudioSource, and ToneGeneratorAudioSource.

virtual void AudioSource::getNextAudioBlock ( const AudioSourceChannelInfo bufferToFill  )  [pure virtual]

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

Implemented in AudioFormatReaderSource, AudioTransportSource, BufferingAudioSource, ChannelRemappingAudioSource, IIRFilterAudioSource, MixerAudioSource, ResamplingAudioSource, and ToneGeneratorAudioSource.


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