DTS: Difference between revisions
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== Frame format == | |||
{| border="1" | |||
! Size !! Explanation !! Value | |||
|- | |||
| 32 bits || Sync marker || 0x7FFE8001 | |||
|- | |||
| 1 bit || Frame type (or last frame) || 0 - termination frame, 1 - normal frame | |||
|- | |||
| 5 bits || Deficit sample count || number of samples in block - 1 (should be 31 for normal frame) | |||
|- | |||
| 1 bit || CRC present || | |||
|- | |||
| 7 bits || Number of blocks || 5-127 | |||
|- | |||
| 14 bits || Frame size in bytes - 1|| 95-16383 | |||
|- | |||
| 6 bits || Channel configuration || values 0-15 are standard, 16-63 are user-defined | |||
|- | |||
| 4 bits || Sample frequency || See table below | |||
|- | |||
| 5 bits || Bitrate || | |||
|- | |||
| '''TODO''' | |||
|} | |||
[[Category:Audio Codecs]] | [[Category:Audio Codecs]] | ||
Revision as of 10:49, 11 February 2007
- Codec ID: 0x2001
- Company: DTS Inc.
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 |
Frame format
| Size | Explanation | Value |
|---|---|---|
| 32 bits | Sync marker | 0x7FFE8001 |
| 1 bit | Frame type (or last frame) | 0 - termination frame, 1 - normal frame |
| 5 bits | Deficit sample count | number of samples in block - 1 (should be 31 for normal frame) |
| 1 bit | CRC present | |
| 7 bits | Number of blocks | 5-127 |
| 14 bits | Frame size in bytes - 1 | 95-16383 |
| 6 bits | Channel configuration | values 0-15 are standard, 16-63 are user-defined |
| 4 bits | Sample frequency | See table below |
| 5 bits | Bitrate | |
| TODO |