From MultimediaWiki
Jump to navigation Jump to search

DTS-HD is an audio coding technology developed by DTS and targeted for the HD generation of optical discs (namely Blu-Ray and HD-DVD). The technology specification embodies various coding modes and extensions to the DTS core.

DTS-HD frames may either extend DTS core (then they will follow each DTS core frame) or form an independent stream of DTS-HD frames only. In the former case DTS-HD frame may contain some extensions to the core frame (e.g. XBR for the additional resolution, XXCh for the additional channels or even XLL for reconstructing the original audio bit-perfectly). Independent DTS-HD frames may contain several streams internally, for example core audio (with possible extensions signalled explicitly), DTS-HD Master Audio (lossless audio) or DTS Express (a low-bitrate codec related to QDesign Music Codec).

The DTS-HD packages begin with the text "dX %", which is in hex "64 58 20 25". There's a length field in the DTS-HD package which tells you how long the DTS-HD package is exactly. If you skip this length, you should end up on the next DTS core package. The length of the DTS-HD package is stored in the bytes 6-8. The lowest four bits of the sixth bytes are the most significant bits of the length field. All 8 bits of the seventh byte are used for the length field. And the 3 most significant bits of the eightth byte are the least significant bits of the length field. Finally you need to add 1 to the length field. So the length calculates like "(sixthByte & 0xf) << 11 + seventhByte << 3 + (eightthByte >> 5) & 7 + 1".