Linear PCM versus Dolby Digital

Ogenec -- Mon, 03/19/2007 - 10:38

I have a question about these two sound formats and the issue of backwards compatibility with my A/V controller. My A/V Controller is the Simaudio Stargate, which does not have HDMI inputs. As a result, when playing Blu-Ray DVDs on my PS3, I use the optical digital connection.

Here's the question. I changed the default on the PS3 audio output from "Linear PCM" to "Bitstream," which in theory should allow me hear at my option uncompressed LPCM or Dolby Digital. I assume that, in a perfect world, LPCM is better. But will my AVC permit me to hear LPCM in all its glory? When I use the LPCM feed rather than the DD feed, the Stargate indicates that it is in Pro Logic Movie (or Music) mode. Is the Stargate "downrezzing" the signal, such that I would be better off using the DD stream? I did a brief A/B comparison with the Casino Royale Blu-Ray DVD -- both formats sounded great, but I found that I preferred the LPCM mode. But I'm not sure if that is because my mind was conditioned to think so.

Bottom line: is my AVC capable of putting through uncompressed LPCM, or should I use the Dolby Digital format?

Thanks, Chidi

P.S. If this post is more appropriately placed somewhere else, please let me know.

Ogenec -- Mon, 03/19/2007 - 20:42

[Follow-Up] I did some more digging on the Internet, and I believe that I have the answer, or at least part of it. Although the Blu-Ray DVDs I have ccontain 5.1 discrete channels of LPCM, the PS3's optical digital out only transmits 2-channel LPCM. That is why the Stargate shows "Pro Logic Movie" -- it is taking the stereo LPCM and generating 5.1 from that.

The question, however, remains. If the Stargate can take stereo uncompressed LPCM and generate 5.1 through Pro Logic, isn't that better than listening to the 5.1 Dolby Digital or DTS feed, which are by definition lossy compression schemes? As I mentioned in the first post, that is the way I listened to Casino Royale last night and it sounded GREAT.

Again, any info on this would be much appreciated. Thanks.

Chidi

tbartela -- Thu, 03/29/2007 - 19:50

hi! i know your post was a year ago almost, but just registered when searching for answers to my similar issue. i have a jvc rx-d702b receiver/tuner/ampllifier, a Panasonic s52s upconversion dvd p[layer, and Onkyo sks-ht-ht540 7.1 speakers. my AV connection is through hdmi, and until recently was a decent experience via my aiwa speakers. now that i've upgraded to the onkyo, i can only get a 2.1 out through the panasonic mix remasteer options #2 and #3 and only as linear pcm audio...meaning the front two and one center speakers work! the cable length is appropriate for both hdmi and speakers, the impedance is compatible, total harmonic distortion is within range, and speaker polarity is correct across the board. i've no idea what might have caused this perplexed situation. there';s no lfe coming through the sub either. the dvd player, much like the receiver, has multiple settings for audio and i've tried matching each and every one to no avail. the dvd player has a 2 channel options and a multichannel option but the receiver only recognizes an audio stream through multichannel but only as a 2 channel! neither jvc or panasonic have replied yet and i've exhausted my options, time, and patience. has your issue been resolved or do you have any suggestions for me? thanks!

Tom Martin -- Fri, 03/30/2007 - 06:45

Chidi is right about the PS3. The instruction manual makes it clear that HDMI is the only route to MC audio.

As for tbartela, when you changed speakers, what else did you change (obviously changing the speakers alone shouldn't kill the rears and the sub, unless you have a speaker problem)?

CEO and Editorial Director, Nextscreen LLC

Anonymous (not verified) -- Tue, 02/24/2009 - 08:21

I just recently got 7.1 hooked up to my ps3 using a hdmi cable. I was running 5.1 but my sterio is a 7.1 so i just added the 2 other speaker, as soon as i did that none of the rear speakers work. Why is that? My reciever is a yamaha 6190 Inever changed anything, but added tthe 2 speakers and it is very frusterating cause i cant figure out the problum if anyone has an answer that would be great