Inside Macintosh: Sound /

Chapter 6 - Audio Components / Audio Components Reference

Audio Component-Defined Routines / Managing the Mute State

AudioGetMute

An audio component can implement the AudioGetMute function. The Sound Manager calls this function to determine the current mute state of an audio port.

pascal ComponentResult AudioGetMute (ComponentInstance ac, 
                                       short whichChannel, 
                                       short *mute);

ac

A component instance that identifies your audio component.

whichChannel

The channel or channels whose mute state you should return.

mute

On output, the current mute state of the specified channel.

DESCRIPTION

Your AudioGetMute function is called by the Sound Manager to determine the current mute state of one or more channels of an audio port. The following constants define the mute states you can return in the mute parameter:

#define audioUnmuted             0        /*device is not muted*/
#define audioMuted               1        /*device is muted*/

The whichChannel parameter indicates the channels or channels whose mute state you should return. The following constants are defined for the whichChannel parameter:

#define audioAllChannels         0        /*all channels*/
#define audioLeftChannel         1        /*left channel*/
#define audioRightChannel        2        /*right channel*/

RESULT CODES

Your AudioGetMute function should return noErr if successful or an appropriate result code otherwise. In particular, if your audio component doesn't support software control of mute states, AudioGetMute should return unImpErr.