AEIOAudioUnit Class Reference

Audio unit interface. More...

#import <AEIOAudioUnit.h>

Inherits NSObject.

Instance Methods
(BOOL)	- setup:
	Setup the audio unit.
(BOOL)	- start:
	Start the audio unit.
(void)	- stop
	Stop the audio unit.
(AudioUnit _Nullable)	- AEIOAudioUnitGetAudioUnit
	Get access to audio unit.
(OSStatus)	- AEIOAudioUnitRenderInput
	Render the input.
(AudioTimeStamp)	- AEIOAudioUnitGetInputTimestamp
	Get the last received input timestamp.
(double)	- AEIOAudioUnitGetSampleRate
	Get the current sample rate.
(AESeconds)	- AEIOAudioUnitGetInputLatency
	Get the input latency.
(AESeconds)	- AEIOAudioUnitGetOutputLatency
	Get the output latency.

Properties
AudioUnit _Nullable	audioUnit
	The audio unit. Will be NULL until setup: is called.
double	sampleRate
	The sample rate at which to run, or zero to track the hardware sample rate.
double	currentSampleRate
	The current sample rate in use.
BOOL	running
	Whether unit is currently active.
BOOL	outputEnabled
AEIOAudioUnitRenderBlock _Nullable	renderBlock
	The block to call when rendering output. May be changed at any time.
int	numberOfOutputChannels
	The current number of output channels.
BOOL	inputEnabled
double	inputGain
int	maximumInputChannels
	The maximum number of input channels to support, or zero for unlimited.
int	numberOfInputChannels
	The current number of input channels in use.
AESeconds	IOBufferDuration
BOOL	latencyCompensation
	Whether to automatically perform latency compensation (default YES)

Detailed Description

Audio unit interface.

This class manages an input/output/input-output audio unit. To use it, create an instance, set the properties, then call setup: to initialize, and start: to begin processing.

Typically, you do not use this class directly; instead, use AEAudioUnitOutput and/or AEAudioUnitInputModule to provide an interface with the audio hardware.

Important note: an audio unit with both input and output enabled is only possible on iOS. On the Mac, you must create two separate audio units.

Method Documentation

- (BOOL) setup:

(NSError *__autoreleasing _Nullable *_Nullable)

error

Setup the audio unit.

Call this after configuring the instance to initialize it, prior to calling start:.

Parameters

error

If an error occured and this is not nil, it will be set to the error on output

Returns

YES on success, NO on failure

- (BOOL) start:

(NSError *__autoreleasing _Nullable *_Nullable)

error

Start the audio unit.

Parameters

error

If an error occured and this is not nil, it will be set to the error on output

Returns

YES on success, NO on failure

- (void) stop

Stop the audio unit.

- (AudioUnit _Nullable) AEIOAudioUnitGetAudioUnit

(__unsafe_unretained AEIOAudioUnit *_Nonnull)

unit

Get access to audio unit.

Available for realtime thread usage

Parameters

unit	The unit instance

Returns

The audio unit

- (OSStatus) AEIOAudioUnitRenderInput		(__unsafe_unretained AEIOAudioUnit *_Nonnull)	unit
		(const AudioBufferList *_Nonnull)	buffer
		(UInt32)	frames

Render the input.

For use with input-enabled instance, this fills the provided AudioBufferList with audio from the input.

Parameters

unit	The unit instance
buffer	The audio buffer list
frames	Number of frames

- (AudioTimeStamp) AEIOAudioUnitGetInputTimestamp

(__unsafe_unretained AEIOAudioUnit *_Nonnull)

unit

Get the last received input timestamp.

For use with input-enabled instances, this gives access to the most recent AudioTimeStamp associated with input audio. Use this to perform synchronization.

Parameters

unit	The unit instance

Returns

The most recent audio timestamp

- (double) AEIOAudioUnitGetSampleRate

(__unsafe_unretained AEIOAudioUnit *_Nonnull)

unit

Get the current sample rate.

The sample rate is normally obtained from the current render context, but this function allows access when the render context is not available

Parameters

unit	The unit instance

Returns

The current sample rate

- (AESeconds) AEIOAudioUnitGetInputLatency

(__unsafe_unretained AEIOAudioUnit *_Nonnull)

unit

Get the input latency.

This function returns the hardware input latency, in seconds. If you have disabled latency compensation, and timing is important in your app, then you should factor this value into your timing calculations.

Parameters

unit	The unit instance

Returns

The current input latency

- (AESeconds) AEIOAudioUnitGetOutputLatency

(__unsafe_unretained AEIOAudioUnit *_Nonnull)

unit

Get the output latency.

This function returns the hardware output latency, in seconds. If you have disabled latency compensation, and timing is important in your app, then you should factor this value into your timing calculations.

Parameters

unit	The unit instance

Returns

The current output latency

Property Documentation

- (AudioUnit _Nullable) audioUnit

readnonatomicassign

The audio unit. Will be NULL until setup: is called.

- (double) sampleRate

readwritenonatomicassign

The sample rate at which to run, or zero to track the hardware sample rate.

- (double) currentSampleRate

readnonatomicassign

The current sample rate in use.

- (BOOL) running

readnonatomicassign

Whether unit is currently active.

- (BOOL) outputEnabled

readwritenonatomicassign

Whether output is enabled. Note that changing this value will cause the audio unit to be uninitialized, reconfigured, and initialized again, temporarily interrupting audio rendering.

- (AEIOAudioUnitRenderBlock _Nullable) renderBlock

readwritenonatomiccopy

The block to call when rendering output. May be changed at any time.

- (int) numberOfOutputChannels

readnonatomicassign

The current number of output channels.

- (BOOL) inputEnabled

readwritenonatomicassign

Whether input is enabled. Note that changing this value will cause the audio unit to be uninitialized, reconfigured, and initialized again, temporarily interrupting audio rendering.

- (double) inputGain

readwritenonatomicassign

The microphone gain, as power ratio. If the current audio session permits, this will be applied using AVAudioSession's gain controls. Otherwise, it will be applied by affecting the input signal directly.

- (int) maximumInputChannels

readwritenonatomicassign

The maximum number of input channels to support, or zero for unlimited.

- (int) numberOfInputChannels

readnonatomicassign

The current number of input channels in use.

- (AESeconds) IOBufferDuration

readwritenonatomicassign

The IO buffer duration. On iOS, this is fetched from AVAudioSession; on the Mac, this is taken from HAL

- (BOOL) latencyCompensation

readwritenonatomicassign

Whether to automatically perform latency compensation (default YES)

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

• AEIOAudioUnit.h