DTS (Digital Theater Systems), is a multi-channel digital surround sound format used for both commercial/theatrical and consumer grade applications. It is used for in-movie sound both on film and on DVD, and during the last few years of the format's existence, several Laserdisc releases had DTS soundtracks.
The basic and most common version of the format is a 5.1 channel system, similar to a Dolby Digital setup, which encodes the audio as five primary (full-range) channels plus a special LFE (low-frequency effect) channel, for the subwoofer.Note however that encoders and decoders support numerous channel combinations and stereo, four-channel and four-channel+LFE soundtracks have been released commercially on DVD, CD and Laserdisc.
Other newer DTS variants are also currently available, including versions that support up to seven primary audio channels plus one LFE channel (DTS-ES). DTS's main competitors in multichannel theatrical audio are Dolby Digital and SDDS, although only Dolby Digital and DTS are used on DVDs and implemented in home theater hardware.
In theatrical use, information in the form of a modified time code is optically imaged onto the film. An optical LED reader reads the timecode data off the film and sends it to the DTS processor which uses this timecode to synchronize the projected image with the soundtrack audio. The actual audio is recorded in compressed form on standard CD-ROM media at a bitrate of 1,103 kbit/s. The processor also acts as a transport mechanism, as it holds and reads the audio discs. Newer units can generally hold three discs, allowing a single processor/transport to handle two-disc film soundtracks along with a third disc containing sound for theatrical trailers. In addition, specific elements of the imprinted timecode allow identifying data to be embedded within the code, ensuring that a certain film's soundtrack will only run with that film. DTS provided the Digital Audio for IMAX until 2001, when Dolby took over.
DTS and Dolby Digital (AC-3), DTS's chief competitor in the cinema and home theater market, are often compared due to their similarity in product goals. In theatrical installations, AC-3 audio is placed between sprocket holes, leaving the audio content susceptible to physical damage due to film wear and mishandling. DTS audio is stored on a separate set of CD-ROM media, whose greater storage capacity affords the potential to deliver better audio fidelity. However, the separation of print film and audiotrack is both a blessing and a curse. AC-3 (and SDDS) reside entirely on the 35 mm film itself, simplifying distribution by eliminating an extra (optional) deliverable. But DTS's CD-ROM media is not subject to the usual wear and damage suffered by the film print during the normal course of the movie's theatrical screening. Disregarding the separate CD-ROM assembly as a potential point of failure, the DTS audiopath is comparatively impervious to film degradation, excepting that the film-printed timecode is completely destroyed.
Both music and movie DVDs allow delivery of DTS audio tracks. But DTS was not part of the original DVD specification (1997), so early DVD players did not recognize DTS audio tracks at all. The DVD specification was revised to allow optional inclusion of DTS audio tracks. The DVD title must carry one or more primary audio tracks in AC-3 or LPCM format (in Europe, MPEG-1 is also an allowed primary track format). The DTS audio track, if present, can be selected by the user. Modern DVD players generally rely on an external home theater receiver to decode DTS audio. DVD players with integrated DTS 5.1 decoders exist, but are not particularly common. Nearly all standalone receivers and many integrated ("home theater in a box") DVD player/receivers manufactured today can decode DTS.
DTS NEO:6, like Dolby's Pro Logic IIx system, can take stereo content and convert the sound into 5.1 or 6.1 channel format.
DTS 96/24 allows the delivery of 5.1 channels of 24-bit, 96 kHz audio and high quality video on the DVD-Video format.
DTS-HD High Resolution Audio, like DTS-HD Master Audio, is an extension to the original DTS audio format. It delivers up to 7.1 channels of sound at 96 kHz sampling frequency and 24 bit depth resolution. DTS-HD High Resolution Audio is selected as an optional surround sound format for Blu-ray Disc and HD DVD with constant bit rates up to respectively 6.0 Mbit/s and 3.0 Mbit/s. It is supposed to be an alternative for DTS-HD Master Audio where disc space may not allow it. For more info:http://www.dtsonline.com/
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