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PCM5.1 & lossless audio discussion - split thread from A Knight's Tale review (1 Viewer)

RobertR

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You are aware that many audiophiles do not accept that statement as categorically true, yes, David?
 

DaViD Boulet

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Like everything that involves human perception, there's debate.

We have audiophiles who claim that Dolby Digital on DVD is transparent, and those who think that it isn't. We have audiophiles who think that DTS sounds better than Dolby Digital, and those who don't. We have audiohpiles who think that MP3 sounds just as good as LPCM and those who don't.

Just like we have audiophiles who think that 20 bit sounds no better than 16 bit, and those who do.

Different strokes. Different ears!

:D
 

RobertR

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And that's why I think DVD-A and SACD failed and why "hires" audio (better than 16/48) on the HD formats won't be a big deal. There simply is no clear, convincing case made for why they're needed, even among audiophiles (let alone the mass market!).
 

DaViD Boulet

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Actually,

DVD-A and SACD have succeeded in becoming a niche market for devoted audiophiles for the simple fact that the subtle improvements in audio quality that they offer are appreciated by those listeners.

As far as general audio listening goes... SACD and DVD-A pissed off and confused most "regular" consumers with more format wars (including this audiophile who *can* hear the improvement they bring) coupled with the trend over the last five years of consumers abandoning high-quality LPCM audio altogether in favor of MP3 and compressed web-downloading for convenience.

I don't think you'd suggest that typical MP3 files compressed for the web sound transparent to the original 16/44.1 CD LPCM audio, so clearly there's more besides "good sound" that's motivating today's music consumers (ie, the small success of DVD-A/SACD cannot be flatly interpreted as an indication of the sound quality of higher resolution). It's actually a miracle that SACD/DVD-A have survived at all given how small a group focus on sound-quality as a key issue in their buying.

However, since most HT enthusiasts adopting high-end formats like HD media have substantial investments in audio gear and tend to appreciate the fidelity of good 5.1, there may actually be a better chance for high-res/lossless might encoding on HD media than DVD-A/SACD.

I know I never wanted to bother with the SACD/DVD-A format war, but I'm holding off for ful 5.1 Dolby-True HD/DTS-HD/DD+ on HD media!
 

RobertR

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There are a lot of potential variables whose values I don’t know to really enable me to answer that question. Examples: Do we really know that identical masters were used (was any OTHER processing done)? What about the psychoacoustics involved? Do people hear differences for the same reason they hear differences with cables, power cords, and sorbothane feet? Is there some slight increase in noise?
 

RobertR

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You included DD+ in your list. So if HD titles come out with superb picture quality that has people ranting and raving and DROOLING, but “only” have DD+, you’ll be satisfied? I think pretty much everyone will be.
 

MandyHan

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The majority will be fine with DD+. The majority of people don't think to switch audio to DTS on discs that have it.
 

DaViD Boulet

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Regarding DD+,

I will be the first to attest that for many titles DD+ will be more-than-adequate for most listeners (even critical listeners). Having already listened to the DD+ soundtracks on a host of HD DVDs (transcribed to 1500 kbps DTS, so it wasn't even full DD+ quality) I can state that without exception the audio quality was far superior to any DVD I've ever heard... open, natural, nuanced and "analog" just like the old days with laserdisc.

I'm sure for many music-video titles, or films with commanding soundtrack scores like LOTR, Amadeus, Star Wars etc., Dolby THD will still offer a meaningful value for critical listeners. But certainly even Dolby Digital Plus is an enourmous step above "typical DVD" sound quality.
 

Dan Hitchman

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I'm in the camp that wants full master soundtrack quality (usually not 16 bit!) losslessly encoded. Many new soundtracks are 24/48 and are starting to go to 24/96 at some audio post houses. Music titles and audio-only discs should be able to go up to 24/192.

Analog and even original 16 bit digital masters can sound much better if they are sampled (or in the case of 16 bit masters, up-sampled using audiophile gear) to 24/96 or 24/192.

If the film was mixed with a back channel, then they should use the 6.1 discrete sound stems (from which many DTS-ES 6.1 Discrete tracks are derived), not the 5.1 EX mixdown with matrixed back channel.

Also, if they can do a good 8 channel high resolution mix, I'm all for that as well.

They really don't have to waste space on an uncompressed LPCM track unless it's audio-only and/or there's room. That's what Dolby TrueHD is for.

Dan
 

Michael Osadciw

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wow! I'm amazed at the direction this thread took! I left the forum for a few days and there is some great audio discussion here! I'm happy to see many people who care about the audio as much as I do with these HD disc formats. Bravo to everyone!

David, thanks for the contributions, and everyone else: thanks for your discussion!

...now back to more film reviews for me. I'm looking forward to seeing more excellent discussions in this HD world of ours!

Ciao guys.
Mike
 

Roger Dressler

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If we were to look at an ideal audio chain, where the lossless audio remained untouched and bit accurate as far as possible, I guarantee that those bits will never reach the DAC intact. Somewhere between the lossless decoder’s output and the DAC there are inevitable things like bass management, room EQ or tone controls, a 48->96 kHz upsampler, maybe even a THX thingy. Try to remember the No. 1 purpose of lossless coding is to avoid perceptual coding. The rest of the chain remains with us.
 

Roger Dressler

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Maybe Filmmixer will comment, but listening to the stems would not necessarily represent what the mixer wanted you to hear. It could require a new mixing session to create a 6.1 presentation mix from those stems.

Here’s an example. Consider that Dolby EX movies are mixed in the presence of the EX encoder-decoder chain. Let’s say the producer wants to have some “space ship” room tone coming from all 3 surround channels (Ls, Cs, Rs) so it spreads evenly around the theater. The room tone sound loop is mono, perhaps. He mixes it equally into the Ls/Rs channels of the 6.1 effects stem, and due to the special +/- 45 degree phase shifters in the Dolby EX encoder, the signal from the monitor EX decoder is spread evenly to all three surround outputs. (The EX encoder is a handy creative tool in such cases.) So looking at the 5.1 track on the DVD made from this theatrical mix, the room tone resides in Ls/Rs at +/- 45 degrees, or a 90-deg total relative difference.

Now it's time to offer a 6.1 discrete version. In listening to the stems directly, we find there’s no room tone in the Cs channel at all. So it has to be added—if they care enough to replicate the immersive effect. That’s a remix. And if they're going to make the effort, why not brew a nice 7.1 rendition?
 

DaViD Boulet

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Roger,

As always, your direct-input is graciously appreciated!


Very true that the first priority of losselss is to avoid perceptual decoding. But from an audiophile perspective even the DSP that you mention like bass management etc. is often bypassed by purists listeners if possible (and if a high-end processor can't bypass DSP for "direct" PCM conversion I hope and pray that their digital algorithms are as transparent as possible...). That outlaw analog cross-over for bass management sounds better than many of the bass-management DSP circuits that I've heard and sounded more "natural" than the bass management in my B&K processor. Though there does seem to be a growing trend these days even in "high end" processors that non-defeatable DSP is becoming more and more the norm.

Naturally if the studio has applied processing like sample-rate conversion and digital EQ to the signal prior to encoding there's nothing the listener can do and these are common practices. However, I've been amazed when comparing "all digital" recordings of the same source recording on multiple formats (16/44.1 CD, 16/44.1 PCM LD, DTS DVD, DD DVD and LPCM 16/48 on DVD) how *different* those encodings often sound from each other...and how "inferior" some of them sometimes sound in comparison to each other... even the LPCM 'lossless' encodings like comparing the CD audio to the LPCM on laserdisc and LPCM on DVD (PCM on DVD tends to sound worst, with PCM CD sounding better, and PCM on laserdisc sounding best of all for whatever reason). Obviously, even in the digital domain audio degradation is possible via poorly implimented DSP... so as an audiophile I'll still take a "less is more" approach to audio mastering and reproduction even when the context is the digital domain. The more those bits are left in tact representing the analog waveform they originally measured the *better*!

;)
 

Roger Dressler

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I randomly pulled True Lies, Lion King, and Clear and Present Danger (I think it was the first DD laser disc). All three use dialnorm at "27" same as the DVDs. Do you have a list of LDs with dialnorm at 31? I'm not saying none exist. I'm just saying your statement is an exaggeration, not unlike several others we see posted here. It might be better to check facts before making blanket charges.
 

Roger Dressler

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I am unaware of any decent processor that cannot defeat bass management. What other DSP process is being imposed in the signal path? And it would be a serious detriment to turn off bass management for 99.9% of users. There is no easy alternative to achieving proper spectral reproduction of all the channels. I doubt Lexicon, or Theta, or Tag McLaren (speaking for myslf) owners would find analog bass management a desirable alternative, nothing against Outlaw. The Outlaw circuit I suspect was aimed at offering bass management for 5.1-ch analog inputs, and thus avoids the cost and degradations of A-Ds.
 

DaViD Boulet

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Roger,

one more question.

Any idea why content providers (like with Mission Impossible), at the moment, are going with straight DD on BD and not using DD+? I read the white-paper a while back and it seemed that all BD players would have no problem extracing the "core" DD from any DD+ track on BD so the lack of full-auido-decoding in the BD player shouldn't be a problem.

I've been *very* impressed with how much better DD+ on HD DVD sounds than any DD DVD/laserdisc at conventional data-rates for those formats and would really love for BD content providers to start using it.

Any thoughts about how much sonic improvement is to be had going to DD+ versus standard DD encoding at 640kbps on BD?
 

Roger Dressler

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I do not have enough experience in our R&D test lab to tell you my impression of that. I need to find some time to do so--I guess it is a rare privilege to have such A/B capability! Anything based on disc A vs disc B has too many variables to say for certain.
 

DaViD Boulet

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My experience is limited to only a few titles... so far all of them Warner Brothers HD DVDs. Curiously, the one that impressed me the most was Blazing Saddles! The orchestral scene in the middle of that film came accross with an "analog" smoothness and rich timberal texture that I associate with LCPM on laserdisc. All of us in the room looked at each other and remarked that the sound had more realism, more depth and texture, than anything we were used to hearing from DVD. It reminded me much more of the higher-bit rate DD I've heard on D-VHS (moulin Rouge on D-VHS has a marvelous sounding DD track that more or less blows the pants off the DVD's DD track). Oh... and I should add that the DD+ I've "heard" was converted to LCPM and then re-compressed in lossy DTS for transmission via SPDIF!!! So the noticable improvement I've heard hasn't even been the full quality given the additional compression step (can't wait to get an HDMI-equipped decoder).

I've almost always felt dissappointed with the audio quality of DVD... whether DD or DTS... in comparison to the typical LPCM track on laserdisc. DVD audio tends to just sound thinner, less textured, less dimensional etc. So far the HD DVD titles I've sampled... even when recompressed in DTS for SPDIF transmission... have "sounded like laserdisc" in a way that has restored that sense of "aahhhh" I used to associate with movie soundtracks. Given how good these HD discs are sounding out of the gate I'm thrilled that the studios have heard our request for higher-than-DVD-audio-quality in addition to 1080p pictures.
 

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