Audio Unit Component Services

Overview

Audio Unit Component Services provides the C interface for using audio units. An audio unit is an audio processing plug-in used for processing or generating audio data. To find, open, and close audio units, you use a companion interface, Audio Component Services, described in Audio Component Services.

An audio unit is uniquely identified by a triplet of codes known as type, subtype, and manufacturer ID. See the AudioComponentDescription structure in Audio Component Services Reference.

Symbols

Callbacks

AUInputSamplesInOutputCallback

Called by the system when an audio unit has provided a buffer of output samples.

AURenderCallback

Called by the system when an audio unit requires input samples, or before and after a render operation.

AudioUnitPropertyListenerProc

Called by the system when the value of a specified audio unit property has changed.

Data Types

AudioUnit

The data type for a plug-in component that provides audio processing or audio data generation.

AudioUnitElement

The data type for an audio unit element identifier.

AudioUnitParameterID

The data type for an audio unit parameter identifier.

AudioUnitParameterValue

The data type for an audio unit parameter value.

AudioUnitPropertyID

The data type for audio unit property keys.

AudioUnitScope

The data type for audio unit scope identifiers.

AudioUnitParameter

An adjustable audio unit attribute such as volume, pitch, or filter cutoff frequency.

AudioUnitParameterEvent

A scheduled change to an audio unit parameter’s value.

AudioUnitProperty

A key-value pair that declares an attribute or behavior for an audio unit.

Constants

Audio Unit Types

The defined types of audio processing plug-ins known as audio units.

Audio Unit Manufacturer Identifier

The Apple audio unit manufacturer code.

Converter Audio Unit Subtypes

Audio data format converter audio unit subtypes for audio units provided by Apple.

Effect Audio Unit Subtypes

Effect (digital signal processing) audio unit subtypes for audio units provided by Apple.

Mixer Audio Unit Subtypes

Audio mixing audio unit subtypes for audio units provided by Apple.

Generator Audio Unit Subtypes

Audio units that serve as sound sources.

Music Instrument Audio Unit Subtypes

Audio units that can be played as musical instruments via MIDI control.

Input/Output Audio Unit Subtypes

Input/output audio unit subtypes for audio units provided by Apple.

AUParameterEventType

Audio unit parameter event types.

AudioUnitRenderActionFlags

Flags for configuring audio unit rendering.

General Audio Unit Function Selectors

General audio unit component selectors that correspond to functions in the audio unit API.

Result Codes

This table lists the result codes defined for Audio Unit Component Services.