scope:

The present document describes the key components of the DTS Coherent Acoustics technology. This edition has been enhanced to include additional extensions that can be applied either directly to the core, or carried in an extension substream. The extension substream may also be used without the core substream to create new coding profiles.

The original DTS Coherent Acoustics coding system is a modular format designed to permit forward looking enhancements without causing the obsolescence of a baseline "core" decoder. The core decoder supports up to 5.1 channels of audio (5 primary channels with 1 Low Frequency Effects (LFE) channel, at up to a 48 kHz sampling frequency. Through the use of extensions, the core can be enhanced with:

• Additional discrete channels.

• Additional matrixed channels.

• Higher audio sampling frequencies.

The addition of an extension substream provides extensibility to the original coding system by allowing additional channels to supplement the core, resolution enhancement of the core through residual coding extensions and frequency enhancements. An additional benefit of the extension substream is to enable new coding profiles that do not use the core, such as a low bitrate coding mode and an efficient lossless coding mode. When the extension substream is used in conjunction with the core, it is a superset of the original DTS Coherent Acoustics coding system and allows for a simple legacy compatibility by addressing the core substeam only New coding profiles, such as the use of lossless coding without a core and the low bit rate coding profile can maintain compatibility through the use of a low complexity transcoder. The main feature enhancements inherent to the extension substream are as follows:

• More channels and greater flexibility in how they are applied, including replacement channels and dubbing tracks.

• A rich metadata set to permit the combining of audio elements under both program and user control.

• Enhanced metadata specifically for broadcast applications.

• The ability to carry multiple embedded downmixes.