gonk, you siad PCM 5.1 on Blu-ray Discs would be phased out eventually to save disc space. Do you Have any idea when that would be. End of 2007? Sooner? Will new discs have both PCM 5.1 and Dolby HD?

Well, Sony's second-gen players will arrive this summer, and that should herald the beginning of onboard decoding capability across the board. (That player will cost $600, and I saw a comment recently that Sony was theorizing that entry-level Blu-ray players will drop to $300 by this December). The Blu-ray Association has also recently mandated that all players sold after some time in October provide full support for BD-Java (the interactive layer). That transition is going to make it much more reasonable to provide discs that use the new formats instead of PCM.

As for when PCM will start to disappear from new releases, I would say that it's already happening. PCM will always be allowed by the Blu-ray spec, but it has never been required - it was done initially because it was easier to master for when using the format's brand new mastering software and because it was guaranteed to be compatible with the first players. The "bit budget" burden of using uncompressed multichannel PCM is significant, especially when studios would like to use single-layer Blu-ray discs when possible (dual-layer was difficult to get into production and still comes at a cost premium). Studios are already beginning to use DTS-HD (which includes a traditional DTS bitstream that works while we wait for somebody to get a DTS-HD decoder to market) and even old-fashioned Dolby Digital on new releases more often than PCM. Take a look at this batch of recent HD disc reviews at Secrets: of nine Blu-ray discs, only two contained PCM soundtracks. Other batches fared a bit better ( 4 of 9 and 6 of 10 , although one of those six was a music title - something that will always be a candidate for PCM), but the trend has already begun and will likely continue as the year goes on.

gonk, if the Blu-ray players are able to do the decoding then will the audio of dolby true hd be able to carried by optical cables? am i still going to be stuck buying a new pre amp to get true hd even if the blu-ray player does the decoding?

Dolby TrueHD, Dolby Digital Plus, and DTS-HD Master Audio can not be carried by optical or coaxial digital audio. The best that optical/coaxial can do is carry Dolby Digital or DTS - which is why many players have been decoding the new formats and then re-encoding as high-bitrate DD or DTS.

There are a limited number of different ways to handle audio from HD-DVD and Blu-ray players:

1. HDMI v1.3: Pass the undecoded digital bitstream from disc to receiver/processor. Presently impossible because there are no HDMI v1.3 receivers or processors.
2. HDMI v1.1/1.2: Player decodes the bitstream to multichannel PCM and passes the decoded multichannel PCM via HDMI to the receiver or processor.
3. Multichannel Analog: Player decodes the bitstream to multichannel PCM, then converts the PCM to multichannel analog.
4. SPDIF Digital Audio: In cases where the disc contains a legacy digital audio format (Dolby Digital, DTS, or the DD and DTS tracks embedded in Dolby Digital Plus and DTS-HD specifically for backward compatibility), that data can be passed via optical or coaxial. In cases where there is not a legacy digital audio format in play (such as TrueHD), many players will decode the new format and then re-encode as either high-bitrate Dolby Digital or high-bitrate DTS.

Those are our only options.

gonk:

What do you think is the possibility of an outbard conversion unit between the blu-ray HD audio out and
current state pre/pros.

Pracitcal?
Good/Bad idea?
Cost-prohibitive or cost-effective?

I'd say "cost-prohibitive" and thus impractical. The problem with an outboard conversion unit that would take multichannel PCM or digital bitstreams (DD+, TrueHD, DTS-HD MA) from a Blu-ray or HD-DVD player and output multichannel analog is the complexity involved. You need a DSP section that can at least provide things like bass management, time delay, channel calibration, and AV sync adjustment - and probably also some matrix processing modes like Dolby EX, DTS NEO:6, and Pro Logic IIx for cases when the source is 5.1 or less (there are and will continue to be discs that only offer two channels because that's how the movie was originally mixed) - because most multichannel analog inputs bypass all of these functions in a surround receiver or processor. If you include HDMI v1.3 support, you also need that DSP section to support decoding Dolby Digital Plus, Dolby TrueHD, and DTS-HD Master Audio. Then you need DAC's for all eight channels. You also need to make sure the device handles HDCP properly so that it can both establish a handshake with the source and pass the HDMI video on to a display. Consumers may even expect you to have more than one HDMI input on such a device so that you can use it with more than one player (perhaps a Blu-ray player, an HD-DVD player, and a universal DVD player like a Denon or Oppo) to make best use of the significant investment we're now talking about, at which point you need some switching control too. It makes more sense to simply take care of the audio processing in the player and output from there as multichannel analog or to replace the pre/pro with an HDMI v1.1+ model.

This month's first batch of HD reviews at Secrets had nine Blu-ray discs, only two of which had uncompressed PCM tracks. Of the other seven, four had DTS-HD (only one of which with Master Audio), one had DTS-ES, and two had only plain old Dolby Digital. Those two PCM tracks seemed to be the preferred, although of course nobody can actually hear the DTS-HD Master Audio track to know how it might stack up to the PCM. Better or not, PCM still seems to be slowly scaling back on Blu-ray.