Function

AudioUnitScheduleParameters

Schedules changes to the value of an audio unit parameter.

Declaration

OSStatus AudioUnitScheduleParameters(AudioUnit inUnit, const AudioUnitParameterEvent *inParameterEvent, UInt32 inNumParamEvents);

Parameters

inUnit

The audio unit that you want to schedule parameter changes for.

inParameterEvent

One or more parameter events that you want to schedule.

inNumParamEvents

The number of audio unit parameter events represented in the inParameterEvent parameter.

Return Value

A result code.

Discussion

Use this function to schedule changes to the value of an audio unit parameter.

  • A so-called immediate audio unit parameter event takes place at a future time and involves an immediate change from one value to another.

  • A so-called ramped audio unit parameter event begins at a future time and proceeds linearly, over a specified number of audio samples, from a starting value to a final value.

With a single call to this function, you can schedule multiple parameter events. All the events apply only to the current audio unit render call; the events are scheduled as a part of the pre-render notification callback.

When scheduling an immediate parameter event, you provide a new value to be set at the specified sample buffer offset.

When scheduling a ramped parameter, the ramp is scheduled each audio unit render for the duration of the ramp. Each schedule of the the new audio unit render specifies the progress of the ramp.

An audio unit parameter that accepts scheduled events indicates this through its AudioUnitParameterInfo structure.

See Also

Using Audio Unit Parameters

AudioUnitGetParameter

Gets the value of an audio unit parameter.

AudioUnitSetParameter

Sets the value of an audio unit parameter.