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Dolby TrueHD vs. DTS-HD Master Audio on HD DVD/Blu-Ray (2 Viewers)

DaViD Boulet

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Amir at AVS has already confirmed that bandwidth limitations of HD DVD would not permit more than one lossless audio track for most films if optimal picture quality was to be preserved.

Here's how bandwidth matters. And this is true for all disc formats like DVD, HD DVD, and BD:

All content that can be accessed on-the-fly, like multiple angles, subtitles, and soundtracks, is recorded to be read off the disc as a *single stream* and therefore shares (must fit into) the same "read rate" or bandwidth of the disc. Think of a Disney DVD with 3 languages... even though your listening to just one language, the other two 5.1 Dolby signals for French and English are being read off the disc at the same time and are simply not being sent out your digital output. But they're there taking up precious bandwidth space all the same. That's why sometimes DTS has to be scrapped to preserve picture quality etc.... there just isn't enough room along side a 5.1 English mix, 2 other languages, and 2 commentary tracks given the bit space that the video needs. Not enough bandwidth.

Because all video and audio tracks that need "toggle" ability need to be streamed simultaneously they all share the same bandwidth. Were Peter Jackson to decide to give us LOTR on some sort of HD disc in 1080p with lossless 24/96 or 24/48 audio, HD DVD wouldn't have enough bit-space in available bandwidth left over for an additional lossless music-only track of the score (confirmed by Amir at AVS).

Jackson wanted to provide music-only tracks on his last extended cut DVD releases but had to remove them from the featureset because it used too much bitspace and compromised picture quality. With BD, those kinds of "rob Peter to pay Paul" bit-allocation concessions would be much less of a problem. With HD DVD, we have the same tug-of-war for bandwidth as we do on DVD, only in High-defintion.
 

Cees Alons

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More reason NOT to have two lossless tracks on the disc, it seems (as long as the players continue to do that).


Cees
 

DaViD Boulet

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Hey Cees,

what are you referring to?

If you're talking about bandwidth, all disc formats read all streaming content simultaneously... that's the way data is stored and read (ie, not player dependent... it's a laser/disc issue basic to all disc media).

In any case, my point was that BD has the bandwidth to make it a non-issue as far as dual-lossless tracks or even dual 1080P streams (like for alternate angles for HD special features or for future 3-D applications).
 

Cees Alons

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Ha, ha, that wasn't too clear. Sorry for that.

I meant to say: the physical constraints that don't allow more than 1 lossless track, are not the only one. There are more reasons, especially the fact that it's rather illogical to get the original bit-for-bit master track back from two different possible sources.

In other words: why would anyone want more than one (even if it would be possible)?


Cees
 

DaViD Boulet

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Cees,

Why would it be illogical to want a lossless high-res version of the movie's original soundtrack as well as for a music-only recording of the film's musical score? Most folks who listen to music-only tracks are audiophiles and a full, lossless quality audio track on a BD would essentially provide the full film soundtrack of a film like Amadeus, Ben-Hur, Lord of the Rings etc. in DVD-Audio quality. It would be like having a free DVD-A.

I'm not suggesting that one needs to use lossless for other "secondary" soundtracks like language dubs etc. But a film's music score seems like a good candidate for 24/96 lossless to my ears (and that of most audiophiles that I know).
 

ChristopherDAC

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I think Cees' point was that having, say, a TrueHD track and a dts-HD/MA track, both with the same audio content, is pointless, not that one should oppose having both a lossless movie-soundtrack and a lossless isolated-music track, or something of that kind. I've been saying so, but some here have called for just that.
 

ppltd

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I think if we look at this logically, both formats will be able to handle what 99.9 % of the buying public will want or care about. The 'What if's' (Like dual 1080p for 3D), and "Wants" (like seperate music only tracks) would be nice, but have little reality in the studios marketing.

What I want is a great picture and a single lossless soundtrack. After that, put it on a second disk.

One truth here, add more "would like to have's" on the disk and the price will go up accordingly, and that is something I do not think any one wants.
 

DaViD Boulet

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Both music-only tracks and 3-D video streams or HD multi-angle are things that cannot be placed on a 2nd disc, but need to share bandwidth with the feature presentation.

BTW, I'm not sure that the notion that 99% of the public share the goal of merely an optimal feature presentation. Bonus features, and HD-resolution bonus features, will be a driving force with HD media as bonus features have been a driving force with DVD.

Many DVDs sacrifice AV quality of the feature presentation to provide "extras" that the studios know sell the discs to the mass consumer. I don't see why consumers would want to give up features with HD media, although certainly many types of features, like documentaries, could be hosted on a 2nd disc. The beauty of the BD format is that it has the bandwidth and the space to provide special features *without* sacrificing the quality of the feature presentation. That's a win-win.
 

Cees Alons

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This is where I disagree. I don't need to see the feature while listening to the music-only track (else, what would the word mean?). But indeed, as Chris said, I was referring to different codecs to obtain exactly the same result (like some people seem to be asking for). If there is TrueHD with the feature there's absolutely nothing to gain by having an additional DTS HD/MA and vice versa.

It would indeed be so illogical that it almost disgusts me.
If people think that they can hear a difference listening to another version (arriving at them through other means) of a bit-to-bit-equal-to-the-original-master-track audio presentation, we really need to teach them.

(THis has nothing to do, of course, with instances or practices where both are not equal. But then you wouldn't want the [most] erratic one.)


Cees
 

DaViD Boulet

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Oh, I agree on that point totally. Was anyone suggesting that there needs to be more than one lossless representation of the same audio signal on the same disc? Naturally, that makes no sense.

What I thought folks were talking about earlier was whether the process DTS uses to achieve "lossless" was really bit-for-bit lossless or not (my bet is that assumptions that it's not truly lossless are misguided and we'll get confirmation that it is. In which case, just one lossless version is all you need!).
 

ppltd

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All you need to do is look at what the average consumer has in his living room, at how well the 39.00 Apex DVD players sell at Wal-Mart, and how many raid the 5.00 bin at their local department store. I am sorry, but I disagree with you. Videophiles are a rare breed, not the driving force in the market place, and HD, to survive, must appeal to that group, not us.

As far as bonus features driving the market, I agree. But that does not require dual 1080p outputs, multiple lossless soundtracks, separate music only soundtracks. These are not the special features the general public will care about. They are more interested in the making of 'HBO' special, or the games, etc.

I my particular case, I find 95 % of the special features a waist of time. If I want a music only soundtrack, I am probably looking for a CD, not a DVD. Just my opinion.
 

DaViD Boulet

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I didn't say that lossless audio quality and pristine video were the consumer's primary concerns. I said that special features were important to them... in fact... *more* important, in some cases, than the quality of the presentation.

I'm not sure if we're disagreeing on those points. Sounds like we're saying the same thing there.

Note: I'm not saying that lossless audio is the particular special feature that the average consumer will demand. I'm only stating that special features, in general, are a driving force in consumer sales of home-video media. However, in the long haul I do think that 3-D will have a big appeal for the mass market as it's a "wiz bang" feature that doesn't require videophile image quality or high resolution audio systems to enjoy... regular people with inexpensive LCD shutter glasses will be able to watch 3-D on any future display that can accept a 48 Hz signal natively (and most future digital display will do just that). Gaming will go 3D first. And then the gaming crowd will pave the way for 3D entertainment. Personally, I'd love to see a 1080P 3-D version of my favoriate IMAX films.

The nice thing about the BD format is that (in the right hands/studio) it can provide all things to all groups: features to those who like them, quality AV to those who appreciate it, and a combination of the two to those who enjoy that.
 

Ed St. Clair

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MarekM,
I see your point, butt I think its worse than that!
It's not only were a TrueHD (say 16 bit) is "only average" (underwhelming), its where a title without TrueHD, butt with DD+ could be "best" (outstanding).
That's a problem for me cause I was thinking; TrueHD = Good & DD+ = not as Good. Wrong!!! :-0

We (audiophiles & HT enthusiast) are not going to be falling all over ourselves, just because a title has TrueHD & conversely it will not be disappointing or lacking SQ if a title is 'only' DD+.

Marek, I can't evaluate any HD titles, if you'd like to checkout how "good" DD+ titles are I'd look into the Universal releases. Which the company has worked on, to get "best" out of that format (24 bit).

I'm a "simple" guy, I wanted TrueHD & DTS Master soundtracks to have the best possible SQ on HD discs.

Marek, have you favorites, and non-favorites, TrueHD titles?

(I am trying to get a TrueHD thread started, so that everyone can post their rankings)
 

JeremyErwin

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FYI, the poster confused Dolby Digital Plus (lossy) with Dolby TrueHD (lossless). And plain old dolby digital with the new variant.
 

Ed St. Clair

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Jeremy,
Are you posting on the post I posted by: bfdtv?
Whew! ;-)
Anytime specifically? Or, though out the entire post?
Thanks.
 

JeremyErwin

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hmm. let's see

For six channel (not 5.1)
48/16 4608 kbs
48/20 5.760 kbs
48/24 6912 kbs
96/24 13824 kbs
192/24 27648 kbs

Now, MLP claims that it can reduce this to

48/16 1440-3456 kbs
48/20 2592-4608 kbs
48/24 3744-6760 kbs

96/24 6336-9216 kbs
192/24 11520-17280 kbs

so perhaps I jumped the gun. Those truehd bitrates looked a little low, but 48/16 doesn't take up too much space. I'm not sure what 48/16 is supposed to be bit for bit identical to. Isn't higher dynamic range used for movie mixing?

Maybe a 5.1 soundtrack is 85% the size of the corresponding six channel arrangement, but I'm not sure how this affects mlp.
 

DaViD Boulet

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It means lossless in the context of the LPCM track used as the source for the compression. If this happens to be the same 24/48 original master soundtrack for the film then that's ideal. If it happens to be a 16/48 LPCM downconversion then it's still lossless, but only "bit for bit" accurate to the 16/48 downconversion... sadly, not the "real" 24/48 or 24/96 master track.
 

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