Mac OS Sound

New Sound Commands

There are two new sound commands that support the sound clock: clockComponentCmd and getClockComponentCmd . These commands are used by QuickTime to obtain the sound clock which is used as the main time base.

The Sound Manager sound clock is only available when QuickTime is installed. This allows QuickTime's video to be synchronized with the audio stream, and can be used to synchronize multiple audio sources as well. There is one sound clock per source (for example, sound channel) which is updated with each hardware buffer. The sound clock counts samples being consumed by the hardware device as it is passed from the Mixer.

Once the clock ComponentInstance has been obtained, any and all of the QuickTime clock component calls (for example, ClockGetTime ) can be used.