MTCoreAudio Constants and Types Reference

These types and constants are used in MTCoreAudio.framework.

MTCoreAudioDirection

An MTCoreAudioDirection is used to specify the section of an audio device, either input or output.

typedef enum MTCoreAudioDirection {
	kMTCoreAudioDevicePlaybackDirection,
	kMTCoreAudioDeviceRecordDirection
} MTCoreAudioDirection;

kMTCoreAudioDevicePlaybackDirection

Specifies the playback (output) section of an audio device.

kMTCoreAudioDeviceRecordDirection

Specifies the record (input) section of an audio device.

MTCoreAudioStreamSide

An MTCoreAudioStreamSide is used to specify the logical or physical side of a stream when querying or setting stream formats.

typedef enum MTCoreAudioStreamSide {
	kMTCoreAudioStreamLogicalSide,
	kMTCoreAudioStreamPhysicalSide
} MTCoreAudioStreamSide;

kMTCoreAudioStreamLogicalSide

Specifies the logical side of a stream; that is, the side that interfaces with the application program. Note that for 'lpcm'-format, samples in the logical side are always 32-bit floating point.

kMTCoreAudioStreamPhysicalSide

Specifies the physical side of a stream; that is, the side that interfaces directly with the audio hardware. The physical and logical stream formats may differ significantly, at the discretion of the device driver.

MTCoreAudioVolumeInfo

An MTCoreAudioVolumeInfo conveys all the useful information about a channel's volume-related settings all at once. It is only returned as the result of a query.

typedef struct _MTCoreAudioVolumeInfo {
	Boolean hasVolume;
	Boolean canSetVolume;
	Float32 theVolume;
	Boolean canMute;
	Boolean isMuted;
	Boolean canPlayThru;
	Boolean playThruIsSet;
} MTCoreAudioVolumeInfo;

hasVolume

true if this channel has a volume associated with it, and false if it does not.

canSetVolume

true if this channel's volume can be changed, and false if it is static.

theVolume

The volume of this channel, between 0.0 and 1.0. Valid only if hasVolume is true.

canMute

true if this channel can be muted.

isMuted

true if this channel is currently muted.

canPlayThru

true if this channel supports Play-Thru mode, in which the record section is routed directly by the hardware to the playback section.

playThruIsSet

true if this channel is currently in Play-Thru mode.