Short for Digital Theater Sound - Extended Surround. It is a 6.1 matrixed system enabling cinemas to deliver extreme spatial effects that literally surround the audience. A rack-mounting DTS-ES decoder creates a back surround channel from encoded surround tracks, in typical theatre applications feeding a back surround (BS) speaker array (configured as left-back-wall and right-back-wall for stereo operation). The system is compatible with all current extended surround formats and an auxiliary surround channel is also provided for other applications. ES modes can be selected via automation inputs or via the built in DTS timecode reader, which detects ES serial numbers for automatic DTS-ES playback.
Star Wars: Episode I was the first of a number of films using an additional rear channel routed to the array of speakers along the back wall of a cinema. In the cinemas, this back channel is not a discrete channel, but is matrixed into the left and right surround channels, much as the center front channel was matrixed into the left and right front channels in earlier matrix optical surround formats.