Roogs Benoit's DD/DTS test (ORIGINALLY "Ever wish they would drop DTS to fit movies on one disc - Page 2

David Susilo · 09-12-2003, 06:23 PM

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What does all this mean? It means that DTS and DD soundtracks may very well sound very different on various production-DVD incarnations for a variety of reasons...and that the DD or DTS codec may not necessarily be the most significant contributor.

Didn't I used to say that? I guess my sound mastering experience doesn't count.

(actually, it really doesn't count... don't want to be sued

)

Regardless, DTS & DD debates are like car accidents. You know it's pointless to get involved but it makes you want to look anyway.

**HTF Ads**

Adam Barratt · 09-12-2003, 06:31 PM

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If you read back to page 1, you'll see he was referring to DTS encoded 20/48 masters compared to 16/44 PCM.

As I said, no qualifications were made in the blanket "All". I must also have just misread the follow-up:

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Adam, every DTS recording that I have heard in any system has sounded far superior to any 16/44.1 CD. Perhaps they were all encoded from 20/48 masters? I'm just describing what I've heard.

This makes no sense to me, as many of these soundtracks undoubtedly used 16-bit masters. It sounds like what you are hearing is a side-effect or distortion caused by DTS encoding, and judging this to be an improvement (as may be the case with perceived analogue "smoothness").

I don't see how this could be a genuine improvement if it is (apparently) altering the sound of the source in such a way.

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We all know that most DD soundtracks on DVD have been altered/processed heavily compared to their theatrical-mix masters. DTS soundtracks may emerge more frequently with less additional modification (this was certainly the case when DTS used to perform all the encoding in-house

Domestic soundtracks are frequently (normally) modified from their theatrical presentations, but this applies equally to DTS and Dolby Digital.

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It's also possible that very often hi-bit masters (like the 24 bit PCM multitrack you used) get encoded in 20-bit resolution on DTS, but the technician fails to encode the DD signal at the same resolution or dithers to the 16-bit level prior to encoding (DD is capable of up to 20-bit resolution if I understand correctly).

Both DTS and Dolby Digital are 24-bit capable, and Dolby's Engineering Guidelines manual recommends using a 24-bit master whenever possible.

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And naturally DTS gets to use more bits on DVD than DD gets to use...so depending on the conent and all the other variables combined...this could account for some differences as well.

I'm surprised to see this old chestnut brought up. The 'more bits equals better sound' argument still doesn't hold water. The fact also remains that DTS uses its available data much less efficiently than Dolby Digital, even if more bits are available.

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I've spoken with THX reps who told me how when they are asked to certify an audio mix for DVD that if there is no dedicated 2.0 soundtrack "mixed" for ProLogic playback that it can present a problem for the 5.1 mix as it has to be altered to better suit down-mixing in the player.

There's no 'has' about it. Dolby Digital includes internal options that allow perfectly respectable downmixing without the need to alter the source at all. I suggest you look up the paper Metadata Issues for ATSC Audio on the ATSC or SMPTE websites, or A Guide to Dolby Metadata on Dolby's website for more detail.

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The simple fact that the DD and DTS audio tracks can differ in volume/record level by more than 6db on a DVD tells us that things are not always being kept constant between the two encoded signals!

This again often boils down to an internal function (dialog normalization) which doesn't require any alteration of the source. The volume difference that results has long been a subject of debate, but that's all it is, a difference in playback volume.

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What does all this mean? It means that DTS and DD soundtracks may very well sound very different on various production-DVD incarnations for a variety of reasons...and that the DD or DTS codec may not necessarily be the most significant contributor.

This is what many people here have been saying for a very long time.

Roogs, thanks for your comments. They're very much appreciated.

Adam

David Judah · 09-12-2003, 07:36 PM

Where are all of the double-blind, stastically significant objectivists? They usually come out of the woodwork when this topic pops up, but are now conspicuous by their silence. Interesting.

DJ

DeeAnn · 09-12-2003, 07:52 PM

Okay- I'll be the odd one out in this thread...

My own experience with DD and DTS is that while DD5.1 can at times lack definition and sound a bit hollow or muffled, DTS to my ears is a lot fuller sounding but kind of shrill and harsh. I don't care to listen to DTS for more than a few minutes as it makes my ears feel tired and kind of "sore" (for lack or a better decscription). I probably won't be able to explain this very well, but it's almost like something metallic is being carried along each sound, and it's noticeable both in sound effects and dialog. Whenever I've mentioned this on other forums people want to either blame my equipment (not the fanciest, but SPL'd properly) though I also hear this in theaters (though I am aware the home and theatrical DTS codecs are slightly different from what I've read, but I could be wrong on that). Or they want to get in a peeing contest over who has better hearing, or some just say I'm wrong or must be lying.

So most times I tend to sit these threads out, but the things that caught my attention was first Roogs mention of anomolies (the fact that they exist in both codecs doesn't surprise me at all) but then this:

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This makes no sense to me, as many of these soundtracks undoubtedly used 16-bit masters. It sounds like what you are hearing is a side-effect or distortion caused by DTS encoding, and judging this to be an improvement (as may be the case with perceived analogue "smoothness").

What I'm wondering (not that anybody probably has an answer) is if the same "effect" or whatever it is that makes DTS sound really good (or more "analog" as people describe it, though in my case it's the reverse) to a lot of people the same thing that makes it difficult to me to listen to comfortably?

I'm not trying to be flamey or anything so don't get me wrong. I've just been trying to figure this out.

David Judah · 09-12-2003, 11:37 PM

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The fact also remains that DTS uses its available data much less efficiently than Dolby Digital, even if more bits are available

I think that's an oversimplification because of a different design approach. First, they stack more bits on the front end in encoding so the decoder can be relatively simple and require less upgrading as improvments are made. And secondly, they rely less on psycho-acoustic masking thus reproducing more of the original signal.

DJ

Adam Barratt · 09-13-2003, 12:37 AM

David, I was trying to keep my reply as simplistic as the original argument.

Your point that the the two data management approaches are fundamentally different just reinforces the fact that the cross-system 'more bits is better' argument isn't even worth debating in this case.

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First, they stack more bits on the front end in encoding so the decoder can be relatively simple and require less upgrading as improvments are made. And secondly, they rely less on psycho-acoustic masking thus reproducing more of the original signal.

This looks a little familiar, but I appreciate your attempts to educate me.

Adam

David Judah · 09-13-2003, 01:24 AM

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Your point that the the two data management approaches are fundamentally different just reinforces the fact that the cross-system 'more bits is better' argument isn't even worth debating in this case

Yes, I agree--just giving it a bit of context. I'm here if ya need me.

DJ



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