Enumeration Case

kAudioOutputUnitProperty_EnableIO

Specifies whether audio I/O is enabled for an I/O unit bus-scope combination.

Declaration

kAudioOutputUnitProperty_EnableIO = 2003

Discussion

An I/O unit’s bus 0 connects to output hardware, such as for playback through a speaker. Output is enabled by default. To disable output, the bus 0 output scope must be disabled, as follows:

UInt32 enableOutput        = 0;    // to disable output
AudioUnitElement outputBus = 0;
 
AudioUnitSetProperty (
    io_unit_instance,
    kAudioOutputUnitProperty_EnableIO,
    kAudioUnitScope_Output,
    outputBus,
    &enableOutput,
    sizeof (enableOutput)
);

An I/O unit’s bus 1 connects to input hardware, such as for recording from a microphone. Input is disabled by default. To enable input, the bus 1 input scope must be enabled, as follows:

UInt32 enableInput        = 1;    // to enable input
AudioUnitElement inputBus = 1;
 
AudioUnitSetProperty (
    io_unit_instance,
    kAudioOutputUnitProperty_EnableIO,
    kAudioUnitScope_Input,
    inputBus,
    &enableInput,
    sizeof (enableInput)
);

A read/write UInt32 value valid on the input and output scopes.