Dolby Digital Plus, Dolby TrueHD, and DTS' DTS-HD are the next-gen audio codecs that will be offered with HD DVD and Blu-ray. Both Dolby Digital Plus and DTS-HD will have backward-compatible core 5.1-channel soundtracks imbedded in their signals that can be carried over standard S/PDIF digital interfaces and decoded by the current generation DTS and Dolby Digital decoders in our AVRs and surround processors. Both formats are scalable and will offer much higher data rates than the current lossy formats, and both DTS and Dolby are offering full lossless compression formats with bit-for-bit reconstruction. Dolby's TrueHD uses Meridian Lossless Packing , while DTS' lossless format is the proprietary DTS-HD Master Audio. On HD DVD and Blu-ray both codecs will boast lossless coding for up to eight discrete channels of audio at resolution at least as high as 24-bit/96kHz. The catch is that the new codecs will only be carried digitally in their native form over HDMI 1.3.
This raises obvious questions given that HD DVD players are due in stores next month, while the HDMI 1.3 spec is due only for the first half of 2006. Blu-ray players are also targeted for the first half of '06, and the announcements we've seen for players indicate April to June. How can players incorporate a spec that isn't complete? Ditto goes for any HDMI-compatible surround processor released before the HDMI 1.3 spec is done.
Advisor to the Toshiba HD DVD Group Mark Knox offered a few potential answers. One, he intimated at CES 2006 that it's most likely that the initial HD DVD releases will have current standard DTS and Dolby Digital soundtracks, but at the highest data rates possible (DVDs usually run at lower audio rates to save more bits for the video transfer). Also, six channel analog outputs will be provided on the players, which could be used with the analog multichannel pass-through connectors found on many current AVRs and surround processors.
Going further, Knox also noted that HD DVD players will have the ability to "transcode" the new high-res Dolby and DTS formats to PCM, which can then be carried over the current HDMI spec and should be compatible with a number of current HDMI compatible surround processors and AVRs. Some Blu-ray titles have also been announced as carrying uncompressed digital audio soundtracks as well, which most likely means uncompressed PCM. HD DVD is also spec'd to carry up to eight discrete channels of uncompressed PCM at resolutions up to 24/96, while Blu-ray is spec'd to go all the way up to 24/192.
Knox also informed me that HD DVD players will be software updateable, but it is not yet known for certain that updating to HDMI 1.3 will be a software switch or whether new hardware will be required. All of this news, and the recent revelation that the AACS copy protection scheme to be used by both formats was just completed in the last couple of weeks, raises the question of whether either of these formats is fully complete and ready for prime time. Is the rush to market for both formats increasing the possibility that early adopters may not be able to take advantage of all the new features the new formats promise?
These questions and many others will be answered in the coming months. All we know for now is that it's dicey time to be buying a new disc player or a new surround sound processor or AVR, and formats themselves aren’t likely to be only points of confusion facing consumers as HD DVD and Blu-ray come to market.
