Originally Posted by audiman
Since the D2 is not decoding the DTS-HD MA, what exactly is coming out of it ? i thought it was getting only the DTS core on the LPCM track.
Also, i played a DTS 96/24 from the PS3. One time on lpcm and one time on bistream. I got 6 ch 48 khz (pcm) and DTS 96/24 signal (bistream) at 1536 kbps. Is it normal ?
DTS-HD MA is made up of a "core" (lossy) audio track and extensions that add back in the parts that would otherwise be lost. It is done that way quite deliberately so that the "core" track is easy to extract -- essentially no processing is involved.
Traditional, lossy, DTS bitstreams come in a high and low bit rate form. The low bit rate form has about 1/2 the bandwidth of the high bit rate form. Early DTS tracks on standard DVDs were almost always the high bit rate form as DTS was trying to carve out its competitive position. DTS tracks on many standard DVDs today, however, are the low bit rate form.
The "core" track subset of a DTS-HD MA track is a high bit rate, lossy, traditional DTS bitstream.
The raw PCM track found on many Blu-Ray discs is an uncompressed copy of the studio mix for the movie at a given bandwidth -- usually 48KHz. Since it has never been encoded, it is, by definition, a lossless track.
The result of fully decoding a DTS-HD MA track is a PCM track. The reductioin in size and bit rate resulting from the packing (encoding) of that track into DTS-HD MA means the studios have THE OPTION of using a higher quality PCM track as the source mix -- higher than 48KHz -- while still staying within the capacity and reading-the-disc bit rate limitations of the Blu-Ray disc format.
However, as of today, essentially nobody is taking advantage of that yet.
That is, the PCM which has been used as the source for the DTS-HD MA track is, quite likely, *ALSO* that same 48KHz mix. Which means the raw PCM track is identical to what would come out of fully decoding the DTS-HD MA track!
This may change over time, but right now, that's what most studios are doing. By the way, the PCM mix used as the source for the lossless Dolby TrueHD tracks is also, almost always, a 48KHz mix. As with DTS-HD MA, studios have THE OPTION of using a higher quality PCM mix as the source for their TrueHD tracks, but right now they don't.
[Note: There is a strangeness in the Toshiba HD-DVD players where a setting intended for the SPDIF output can cause the HDMI PCM output to upsample the 48KHz PCM to 96KHz -- and quite poorly by all accounts. If your Toshiba is sending out 96KHz from a 48KHz track you should make it stop doing that.]
However, when you tell the player to send a bitstream version of the DTS-HD MA track over an SPDIF output or over HDMI V1.1 all you will get is the "core" or "compatibility" track. Again that is a LOSSY subset of the DTS-HD MA track -- essentially at the quality level of standard DVD DTS tracks.