The HD DVD standard gives suppliers the option of transcoding all native surround formats on HD DVD discs to either Dolby Digital 5.1, up to 640kbps, or DTS 5.1, up to 1.5Mbps, for transfer through a single-cable S/PDIF output to legacy A/V receivers and preamp/processors, the HD DVD Promotion Group confirmed.
In its first two HD DVD players, Toshiba chose to transcode all audio formats to DTS 5.1. As previously reported (see TWICE, April 10, p. 32), the Toshiba models also transcode all formats to PCM for transfer through a single-cable wider bandwidth HDMI 1.1 output.
In a related matter, Dolby Labs noted that its compressed Dolby TrueHD lossless format exceeds the HD DVD format’s specifications. Dolby TrueHD supports two- to 14-channel performance with each channel delivering up to 192kHz/24-bit performance. The HD DVD spec, however, limits the performance of lossless-compression codecs to two-channel 192/24 or multichannel 96/24, up to 7.1 channels, regardless of the lossless format used.