DTS-HD High Resolution Audio
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.
DTS-HD Master Audio
DTS-HD Master Audio, previously known as DTS++ and DTS-HD, supports a virtually unlimited number of surround sound channels, can downmix to 5.1 and two-channel, and can deliver audio quality at bit rates extending from DTS Digital Surround up to lossless (24-bit, 96 kHz). DTS-HD Master Audio is selected as an optional surround sound format for Blu-ray and HD DVD. Currently the Japanese version Pioneer BDP-LX80 supports bitstream digital output of the format along with the Samsung BD-P1400 (through a firmware update). All Blu-ray and HD DVD players can decode the DTS "core" resolution soundtrack at 1.5 Mbit/s, however. DTS-HD Master Audio and Dolby TrueHD are the only technologies that deliver compressed lossless surround sound for these new disc formats, ensuring the highest quality audio performance available in the new standards. (N.B.: DTS Coherent Acoustics coding system has been selected as mandatory audio technology for both the Blu-ray Disc (BD) and High Definition Digital Versatile Disc (HD DVD).)