Blu Ray Audio - Questions

AsSiMiLaTeD

Okay, so I'm finding conflicting information on what should be a really simple question. Actually, I have a couple questions, highlighted below:

I'm running an optical cable from my Sony BDP to my receiver (can't get audio via HDMI because TV is DVI only, dumb, but that's the way it is).

Question #1 - I believe that I CANNOT get lossless audio via the optical cable, can anyone confirm that this is indeed correct?

The real question is in regards to what's happening when I select the lossless track on the BDP and get the full surround sound on my receiver. Assuming that the answer to question #1 above is yes, in my mind there are only two possibilities:

A: The lossless track is being downconverted into the 'regular' compressed DTS or DD track during playback, or 'on the fly' so to speak
or
B: The 'regular' compressed DTS or DD track actually physically resides on the disc and the player sends that instead since it knows it's using the optical connection.

So, Question #2 - Can anyone tell me confidently which of the two scenarios above is actually happening?

I'm leaning towards option B with the compressed track actually being on the disc, and here's why. I'm comparing two movies I just picked up a couple days ago on blu, Minority Report and Avatar (I oiticed the absence of surround sound with Minority Report, which prompted this whole thing):

So with Avatar, there's a DTS MA lossless track and a bunch of other 'regular' DD tracks. With the lossless track, I get full surround sound, and my receiver shows 'DTS' on the front (not DTS MA, just DTS. So with this movie I know I'm getting full surround sound, and I believe that sound is the compressed track.

With Minority Report, there's also a DTS MA lossless track, a French 'regular' DD track, and a Spanish 2.0 track. With the lossless track selected on this disc, I'm only getting information from the front speakers, no sound from the surrounds at all. If I switch to the French DD track, I do get full surround sound, but of course it does me no good since it's all in French.

So my hypothesis is that scenario B is correct and that the compressed version of the lossless track must also be stored on the disc, and that it simply isn't there on the Minority Report disc.

Any insight is appreciated.

FTGV

What you are getting via optical is the core DTS signal only.To get the extra extension files for full lossless requires an HDMI connection.The DTS HD MA core (and DD true HD core)on Blu Ray has potentially twice the bit rate of DTS and DD of that available on standard DVD.Therfore even with the optical or coax connection it may indeed sound better than the DTS track on standard DVD.

PSOVLSK

FTGV wrote: »

What you are getting via optical is the core DTS signal only.To get the extra extension files for full lossless requires an HDMI connection. Or analog out from BR to AVR The DTS HD core (and DD MA core)on Blu Ray has potentially twice the bit rate of DTS and on standard DVD so even with optical or coax it may indeed sound better.

To the best of my knowledge, FTGV is correct. Your hypothesis sounds good. I look forward to reading what others have to say to find out if you are correct.

phuz

B is pretty much correct. The bandwidth for optical toslink connections is pretty much limited to 2 lossless channels only, or compressed multi-channel. Most blu-rays will have one or the other - DD or DTS - for those still using older recievers or optical connections that do not support lossless multi channel audio via HDMI.

cheddar

DTS-HD MA contains a 'core' DTS track. The player will send this track over optical. Dolby TrueHD does not contain a 'core' track and extentions. TrueHD disks require that a regular Dolby Digital track accompany the TrueHD track for those situations where lossless transmission isn't possible. IIRC, it was written into the standards that way. So all TrueHD disks should have a DD backup included.

cheddar

Oh, and I believe it is possible to send lossless over optical, just in two channels as I think you've noticed. It just doesn't have the bandwidth for full surround. This might be a setting in the setup somewhere where you have 2 channel selected instead of defaulting to the lossless dts 'core' surround track instead. Something to investigate further anyways. I could see how it might happen as you say with a TrueHD track as the backup track is seperate. But all DTS-HD MA tracks should contain a 'core' lossy track that should be accessible if you can't pass lossless.

Are you still seeing DTS on your AVR with Minority Report? Is the player decoding and sending PCM instead? Sounds strange that you player seems to be handling the two movies differently.

Sherardp

FTGV wrote: »

What you are getting via optical is the core DTS signal only.To get the extra extension files for full lossless requires an HDMI connection.The DTS HD MA core (and DD true HD core)on Blu Ray has potentially twice the bit rate of DTS and DD of that available on standard DVD.Therfore even with the optical or coax connection it may indeed sound better than the DTS track on standard DVD.

This is correct. Way to go FTGV.

cheddar

Sherardp wrote: »

This is correct. Way to go FTGV.

On the higher quality of the blu-ray DD and DTS tracks vs. SD-DVD tracks, yes. That there is such as thing as a TrueHD 'core' just like a DTS-HD MA 'core', I think he's mistaken. The backup is just a seperate DD track transmitted at the maximum allowable bitrate.

AsSiMiLaTeD

Ok, i'm getting what you guys are saying, but I'm still confused on one thing:

Why am I getting two different results with Minority Report and Avatar?

On both I'm selecting the lossless audio track, and on both this track is DTS MA (the screen reads DTS HD Master Audio on both movies when I select this track). However, with Avatar I'm getting full surround sound, and the DTS lights up on my receiver (I think it's just the regular DTS, not sure if there's another light for DTS MA), but with Minority Report I'm only getting 2 channels, and no DTS light on the receiver.

cheddar

It sounds like your player is converting the lossless to 2 channel PCM for minority report. It's definitely being handled differently. Probably from the way the disk is authored.

A guy over at AVS is also having a problem with the DTS-HD MA track.

http://www.avsforum.com/avs-vb/showthread.php?p=18537374

Maybe when the player encounters whatever problem this is, its firmware redirects it to play in two channel PCM as a workaround.

FTGV

cheddar wrote: »

On the higher quality of the blu-ray DD and DTS tracks vs. SD-DVD tracks, yes. That there is such as thing as a TrueHD 'core' just like a DTS-HD MA 'core', I think he's mistaken. The backup is just a seperate DD track transmitted at the maximum allowable bitrate.

Yes I concede that the DD track via optical/coax from BR is not the "core" of the True HD signal,but it does hold the potential for a higher data rate.Thanks for the clarification.

POLKHT

You can also get lossless audio, if you have 7.1 analog outputs on your blu-ray player and 7.1 preouts on the receiver. Also the blu-ray player must be able to decode the lossless audio.

AsSiMiLaTeD

I think it's safe to say that any player with a full set of analog outputs is also going to be able to decode the lossless formats.