#import "TPCircularBuffer.h"
#import <AudioToolbox/AudioToolbox.h>

Classes
struct	AECircularBuffer
	Circular buffer. More...

Macros
#define	AECircularBufferCopyAll UINT32_MAX

Functions
BOOL	AECircularBufferInit (AECircularBuffer *buffer, UInt32 capacityInFrames, int channelCount, double sampleRate)
	Initialize buffer.

void	AECircularBufferCleanup (AECircularBuffer *buffer)
	Cleanup buffer.

void	AECircularBufferClear (AECircularBuffer *buffer)
	Clear buffer.

void	AECircularBufferSetAtomic (AECircularBuffer *buffer, BOOL atomic)
	Set the atomicity.

void	AECircularBufferSetChannelCountAndSampleRate (AECircularBuffer *buffer, int channelCount, double sampleRate)
	Change channel count and/or sample rate.

UInt32	AECircularBufferGetAvailableSpace (AECircularBuffer *buffer)
	Determine how many much space there is in the buffer.

BOOL	AECircularBufferEnqueue (AECircularBuffer buffer, const AudioBufferList bufferList, const AudioTimeStamp *timestamp, UInt32 frames)
	Copy the audio buffer list onto the buffer.

AudioBufferList *	AECircularBufferPrepareEmptyAudioBufferList (AECircularBuffer buffer, UInt32 frameCount, const AudioTimeStamp timestamp)
	Prepare an empty buffer list, stored on the circular buffer.

void	AECircularBufferProduceAudioBufferList (AECircularBuffer *buffer)
	Mark next audio buffer list as ready for reading.

UInt32	AECircularBufferPeek (AECircularBuffer buffer, AudioTimeStamp outTimestamp)
	Determine how many frames of audio are buffered.

void	AECircularBufferDequeue (AECircularBuffer buffer, UInt32 ioLengthInFrames, const AudioBufferList outputBufferList, AudioTimeStamp outTimestamp)
	Copy a certain number of frames from the buffer and dequeue.

AudioBufferList *	AECircularBufferNextBufferList (AECircularBuffer buffer, AudioTimeStamp outTimestamp, const AudioBufferList *lastBufferList)
	Access the next stored buffer list.

void	AECircularBufferConsumeNextBufferList (AECircularBuffer *buffer)
	Consume the next buffer list available for reading.

void	AECircularBufferConsumeNextBufferListPartial (AECircularBuffer *buffer, UInt32 frames)
	Consume a portion of the next buffer list.

Class Documentation

struct AECircularBuffer

Circular buffer.

This utility provides a thread-safe and lock-free FIFO buffer that operates on AudioBufferLists and tracks the AudioTimeStamps corresponding to the audio.

It provides a convenience wrapper to TPCircularBuffer and its AudioBufferList utilities, by avoiding the need to provide an AudioStreamBasicDescription to the various functions, among other things.

It's generally preferable to use this interface instead of TPCircularBuffer if you're just using the TAAE audio format (non-interleaved float).

Class Members
TPCircularBuffer	buffer
AudioStreamBasicDescription	audioDescription

Macro Definition Documentation

#define AECircularBufferCopyAll UINT32_MAX

Function Documentation

BOOL AECircularBufferInit	(	AECircularBuffer *	buffer,
		UInt32	capacityInFrames,
		int	channelCount,
		double	sampleRate
	)

Initialize buffer.

Note that the length is advisory only; the true buffer length will be multiples of the device page size (e.g. 4096 bytes)

Parameters

buffer	Circular buffer
capacityInFrames	Amount of audio frames you wish to store in the buffer
channelCount	Number of channels of audio you'll be working with
sampleRate	Sample rate of audio, used to work with AudioTimeStamps

Returns: YES on success, NO on buffer allocation failure

void AECircularBufferCleanup ( AECircularBuffer * buffer )

Cleanup buffer.

Releases buffer resources.

void AECircularBufferClear ( AECircularBuffer * buffer )

Clear buffer.

Resets buffer to original, empty state.

This is safe for use by consumer while producer is accessing the buffer.

void AECircularBufferSetAtomic	(	AECircularBuffer *	buffer,
		BOOL	atomic
	)

Set the atomicity.

If you set the atomiticy to false using this method, the buffer will not use atomic operations. This can be used to give the compiler a little more optimisation opportunities when the buffer is only used on one thread.

Important note: Only set this to false if you know what you're doing!

The default value is true (the buffer will use atomic operations)

Parameters

buffer	Circular buffer
atomic	Whether the buffer is atomic (default true)

void AECircularBufferSetChannelCountAndSampleRate	(	AECircularBuffer *	buffer,
		int	channelCount,
		double	sampleRate
	)

Change channel count and/or sample rate.

This will cause the buffer to clear any existing audio, and reconfigure to use the new channel count and sample rate. Note that it will not alter the buffer's capacity; if you need to increase capacity to cater to a larger number of channels/frames, then you'll need to cleanup and re-initialize the buffer.

You should only use this on the consumer thread.

Parameters

buffer	Circular buffer
channelCount	Number of channels of audio you'll be working with
sampleRate	Sample rate of audio, used to work with AudioTimeStamps

UInt32 AECircularBufferGetAvailableSpace ( AECircularBuffer * buffer )

Determine how many much space there is in the buffer.

Determines the number of frames of audio that can be buffered.

Note: This function should only be used on the producer thread, not the consumer thread.

Parameters

buffer Circular buffer

Returns: The number of frames that can be stored in the buffer

BOOL AECircularBufferEnqueue	(	AECircularBuffer *	buffer,
		const AudioBufferList *	bufferList,
		const AudioTimeStamp *	timestamp,
		UInt32	frames
	)

Copy the audio buffer list onto the buffer.

Parameters

buffer	Circular buffer
bufferList	Buffer list containing audio to copy to buffer
timestamp	The timestamp associated with the buffer, or NULL
frames	Length of audio in frames, or AECircularBufferCopyAll to copy the whole buffer

Returns: YES if buffer list was successfully copied; NO if there was insufficient space

AudioBufferList* AECircularBufferPrepareEmptyAudioBufferList	(	AECircularBuffer *	buffer,
		UInt32	frameCount,
		const AudioTimeStamp *	timestamp
	)

Prepare an empty buffer list, stored on the circular buffer.

Parameters

buffer	Circular buffer
frameCount	The number of frames that will be stored
timestamp	The timestamp associated with the buffer, or NULL.

Returns: The empty buffer list, or NULL if circular buffer has insufficient space

void AECircularBufferProduceAudioBufferList ( AECircularBuffer * buffer )

Mark next audio buffer list as ready for reading.

This marks the audio buffer list prepared using AECircularBufferPrepareEmptyAudioBufferList as ready for reading. You must not call this function without first calling AECircularBufferPrepareEmptyAudioBufferList.

Parameters

buffer Circular buffer

UInt32 AECircularBufferPeek	(	AECircularBuffer *	buffer,
		AudioTimeStamp *	outTimestamp
	)

Determine how many frames of audio are buffered.

Note: This function should only be used on the consumer thread, not the producer thread.

Parameters

buffer	Circular buffer
outTimestamp	On output, if not NULL, the timestamp corresponding to the first audio frame

Returns: The number of frames queued in the buffer

void AECircularBufferDequeue	(	AECircularBuffer *	buffer,
		UInt32 *	ioLengthInFrames,
		const AudioBufferList *	outputBufferList,
		AudioTimeStamp *	outTimestamp
	)

Copy a certain number of frames from the buffer and dequeue.

Parameters

buffer	Circular buffer
ioLengthInFrames	On input, the number of frames to consume; on output, the number of frames provided
outputBufferList	The buffer list to copy audio to, or NULL to discard audio.
outTimestamp	On output, if not NULL, the timestamp corresponding to the first audio frame returned

AudioBufferList* AECircularBufferNextBufferList	(	AECircularBuffer *	buffer,
		AudioTimeStamp *	outTimestamp,
		const AudioBufferList *	lastBufferList
	)

Access the next stored buffer list.

Parameters

buffer	Circular buffer
outTimestamp	On output, if not NULL, the timestamp corresponding to the buffer
lastBufferList	If not NULL, the preceding buffer list on the buffer. The next buffer list after this will be returned; use this to iterate through all queued buffers. If NULL, this function will return the first queued buffer.

Returns: Pointer to the next queued buffer list

void AECircularBufferConsumeNextBufferList ( AECircularBuffer * buffer )

Consume the next buffer list available for reading.

Parameters

buffer Circular buffer

void AECircularBufferConsumeNextBufferListPartial	(	AECircularBuffer *	buffer,
		UInt32	frames
	)

Consume a portion of the next buffer list.

This will also increment the sample time and host time portions of the timestamp of the buffer list, if present.

Parameters

buffer	Circular buffer
frames	The number of frames to consume from the buffer list

Classes

Macros

Functions

Class Documentation

Macro Definition Documentation

Function Documentation