DTS

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Revision as of 10:33, 11 February 2007 by Kostya (talk | contribs) (Some notes on bitstream coding)
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DTS Coherent Acoustics is a perceptual audio codec. The main technique used is a QMF filter together with Huffman, ADPCM and vector quantization.

Specification can be found through the ETSI, search for DTS. Info completeing the incomplete specification can be found here [1], [2] and here [3].

The VideoLAN project has created libdts/libdca an open source implementation of DTS. Unfortunately libdts was pushed underground through patent scare tactics for a while.

Bitstream coding

There are four different bitstream formats -- little- or big-endian and 16 or 14 bits per word.

Raw bitstream coding

Raw bitstream is packed into 16-bit words with possible little- or big-endian.

14-bit words

This kind of bitstream is packed into 16-bit words where high two bits contain some auxiliary information (parity?). This coding is used in many DTS-in-WAV files.

How to distinguish different versions

Every frame in DTS starts with 32-bit syncword which can be used to distinguish current bitstream encoding:

Sequence Bitstream type
7F FE 80 01 raw big-endian
FE 7F 01 80 raw little-endian
1F FF E8 00 07 Fx 14-bit big-endian
FF 1F 00 E8 Fx 07 14-bit little-endian