JUCE  v5.4.1-191-g0ab5e696f
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juce::PositionableAudioSource Class Referenceabstract

A type of AudioSource which can be repositioned. More...

#include <juce_PositionableAudioSource.h>

Inheritance diagram for juce::PositionableAudioSource:
Collaboration diagram for juce::PositionableAudioSource:

Public Member Functions

 ~PositionableAudioSource ()
 Destructor. More...
 
virtual void getNextAudioBlock (const AudioSourceChannelInfo &bufferToFill)=0
 Called repeatedly to fetch subsequent blocks of audio data. More...
 
virtual int64 getNextReadPosition () const =0
 Returns the position from which the next block will be returned. More...
 
virtual int64 getTotalLength () const =0
 Returns the total length of the stream (in samples). More...
 
virtual bool isLooping () const =0
 Returns true if this source is actually playing in a loop. More...
 
virtual void prepareToPlay (int samplesPerBlockExpected, double sampleRate)=0
 Tells the source to prepare for playing. More...
 
virtual void releaseResources ()=0
 Allows the source to release anything it no longer needs after playback has stopped. More...
 
virtual void setLooping (bool shouldLoop)
 Tells the source whether you'd like it to play in a loop. More...
 
virtual void setNextReadPosition (int64 newPosition)=0
 Tells the stream to move to a new position. More...
 

Protected Member Functions

 PositionableAudioSource () noexcept
 Creates the PositionableAudioSource. More...
 

Detailed Description

A type of AudioSource which can be repositioned.

The basic AudioSource just streams continuously with no idea of a current time or length, so the PositionableAudioSource is used for a finite stream that has a current read position.

See also
AudioSource, AudioTransportSource

{Audio}

Constructor & Destructor Documentation

◆ PositionableAudioSource()

juce::PositionableAudioSource::PositionableAudioSource ( )
inlineprotectednoexcept

◆ ~PositionableAudioSource()

juce::PositionableAudioSource::~PositionableAudioSource ( )
inline

Destructor.

Member Function Documentation

◆ getNextAudioBlock()

virtual void juce::AudioSource::getNextAudioBlock ( const AudioSourceChannelInfo bufferToFill)
pure virtualinherited

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 juce::AudioTransportSource, juce::ChannelRemappingAudioSource, juce::AudioAppComponent, juce::MixerAudioSource, juce::AudioFormatReaderSource, juce::BufferingAudioSource, juce::ResamplingAudioSource, juce::ReverbAudioSource, juce::ToneGeneratorAudioSource, juce::IIRFilterAudioSource, and juce::MemoryAudioSource.

◆ getNextReadPosition()

virtual int64 juce::PositionableAudioSource::getNextReadPosition ( ) const
pure virtual

Returns the position from which the next block will be returned.

See also
setNextReadPosition

Implemented in juce::AudioTransportSource, juce::AudioFormatReaderSource, and juce::BufferingAudioSource.

◆ getTotalLength()

virtual int64 juce::PositionableAudioSource::getTotalLength ( ) const
pure virtual

Returns the total length of the stream (in samples).

Implemented in juce::AudioTransportSource, juce::AudioFormatReaderSource, and juce::BufferingAudioSource.

Referenced by juce::BufferingAudioSource::getTotalLength().

◆ isLooping()

virtual bool juce::PositionableAudioSource::isLooping ( ) const
pure virtual

Returns true if this source is actually playing in a loop.

Implemented in juce::AudioTransportSource, juce::BufferingAudioSource, and juce::AudioFormatReaderSource.

Referenced by juce::BufferingAudioSource::isLooping().

◆ prepareToPlay()

virtual void juce::AudioSource::prepareToPlay ( int  samplesPerBlockExpected,
double  sampleRate 
)
pure virtualinherited

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

Implemented in juce::AudioTransportSource, juce::ChannelRemappingAudioSource, juce::AudioAppComponent, juce::MixerAudioSource, juce::AudioFormatReaderSource, juce::BufferingAudioSource, juce::ResamplingAudioSource, juce::ReverbAudioSource, juce::IIRFilterAudioSource, juce::ToneGeneratorAudioSource, and juce::MemoryAudioSource.

◆ releaseResources()

virtual void juce::AudioSource::releaseResources ( )
pure virtualinherited

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 juce::AudioTransportSource, juce::ChannelRemappingAudioSource, juce::AudioAppComponent, juce::MixerAudioSource, juce::AudioFormatReaderSource, juce::BufferingAudioSource, juce::ResamplingAudioSource, juce::ReverbAudioSource, juce::IIRFilterAudioSource, juce::ToneGeneratorAudioSource, and juce::MemoryAudioSource.

◆ setLooping()

virtual void juce::PositionableAudioSource::setLooping ( bool  shouldLoop)
inlinevirtual

Tells the source whether you'd like it to play in a loop.

Reimplemented in juce::AudioFormatReaderSource.

References juce::ignoreUnused().

◆ setNextReadPosition()

virtual void juce::PositionableAudioSource::setNextReadPosition ( int64  newPosition)
pure virtual

Tells the stream to move to a new position.

Calling this indicates that the next call to AudioSource::getNextAudioBlock() should return samples from this position.

Note that this may be called on a different thread to getNextAudioBlock(), so the subclass should make sure it's synchronised.

Implemented in juce::AudioTransportSource, juce::AudioFormatReaderSource, and juce::BufferingAudioSource.


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