The audio component, including DME, of a film composition. There is usually a requirement for sound to be synchronized to the video image. This has been achieved by a variety of means, including the recording of sound on optical tracks etched into the film emulsion alongside the frames, fixing magnetic tracks on the film surface, synchronizing the film with a separate tape machine by means of mechanical sprockets, and electronic sync using systems such as SMPTE. See also Dolby Stereo, LC Concept, SR.D, pilot tone, layback recorder, source track.
