The digital soundtrack, treated with a
digital encoding algorithm, is located on several disks: 2 magneto-optical disks for L.C.Concept and 3 CD-ROMs for DTS Digital Sound. During projection a time code reader, mounted on the projector, reads the standard SMPTE time code track located on the print. This time code makes sure the correct data is read with each frame and provides synchronization of picure and sound. The digital bitstream, read from the disks, is sent to the processors for error correction and decoding by the DACs (digital-to-analog converters) of the encoded data to discrete analog channels. These are sent to the amplifiers or the THX monitor, if the theater is THX certified.
Advantages of this system are the fact that the soundtrack is less susceptible to damage and because it is located on disks it requires a less agressive coding algoritm. A disadvantage is that it it more difficult to keep track of the print as well of the disks. Also it is possible the disks get mixed up. In case of DTS it isn't catastrophic but it does result in playback of the inferior Dolby Stereo SR-compatible back-up soundtrack.