Contains higher-level utility functions for the use of AudioUnit clients.
<AvailabilityMacros.h>,
<AudioUnit/AudioUnit.h>,
<AudioUnit.h>
The AU Parameter Listener is designed to provide notifications when an Audio Unit's parameters
or other state changes. It makes it unnecessary for UI components to continually poll an Audio
Unit to determine if a parameter value has been changed. In order for this notification
mechanism to work properly, parameter values should be changed using the AUParameterSet call
(discussed below). This also makes it unnecessary for an Audio Unit to provide and support a
notification mechanism, particularly as AudioUnitSetParameter may be received by an Audio Unit
during the render process.
The AUEventListener API's extend the AUParameterListener API's by supporting event types
other than parameter changes. Events, including parameter changes are delivered serially to the
listener, preserving the time order of the events and parameter changes.
There are also some utilities for converting between non-linear and linear value ranges. These
are useful for displaying a non-linear parameter (such as one whose units are in Hertz or
decibels) using a linear control mechanism, such as a slider, to ensure that the user has a
wider perceived range of control over the parameter value.