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

That's cold, Roogs.

C'mon, don't leave us hanging like that. (I need a smiley for "pretty please".)

And if it makes any difference, your opinion does matter to at least one person here.

M.

That was cold, but it was brilliant.

Roogs,

I'm with Michael...we just gotta know

If you're not pulling our leg then that certainly would be the best apples-apples comparison possible if one wanted to compare compression-algorithm to compression-algorithm. I state that because it's very possible that *many* of the sound-quality issues listeners consistently hear between various "formats" like DTS or DD may have many factors that come into play in practice other than compression-algorithm.

Some questions do remain given what you describe: Were identical bit-rates used during compression? What was the resolution of the source PCM digital multitrack signal? Was that resolution preserved (I understand that DD can encode up to 20-bit words) or downconverted to the 16-bit level for either or both codecs? Were any additional processing steps employed or avoided? DD has a host of manipulation tools like dialog normalization and EQ etc. that often get used inadvertantly by mastering houses without much expertise.

Private Messaging enabled?

Good God, Roogs, don't go the private message route! Otherwise Boulet will be citing you as one of his unnamed audiophiles for years to come.

M.

Then again he might tell me that he heard no difference!

Interesting that Roogs made his post while I was writing that objective tests had not been performed.

Absolutely. This world would be a very boring place if everyone agreed with everyone else. But the suggestion and subsequent approval of the complete removal of an audio format that is not "up to par" with DTS (although not by much) is not "disagreement".

It's not that I disagree with anything that was said regarding the technology. I'm quite certain that if Roogs tells us what he found (which I hope he will) that DTS will come out ahead. But the concept that DTS is so far ahead of high bit rate DD as DD is to monaural is what always irks me and is exactly what happens every time these DD/DTS threads get started.

So, I guess that it's not that any one big thing that was said in this thread set me off out of nowhere but rather the culmination of small things over time that were ignited by the suggestion that DD should be removed entirely to make room for DTS.

I'm not sure about that. There have been been threads in this forum about how Queen is ignoring DD on their DVD releases to the point that whoever started the one thread got an explanation from Brian May that they were avoiding DD 5.1 because of the loss to its compression but would consider it for future releases.

Very close. You missed the apostrophe. (It's "anyone else's" as it represents ownership of the noun "opinion".)

And again, I don't doubt that. There is very little doubt in my mind that DTS is technologically and audibly superior to DD. It's the DEGREE of superiority that I find very, very difficult to believe, particularly when put on a scale of diminishing returns with monaural, stereo, and ProLogic on the same scale.

The real issue with me is the air of "elitism" exuded in just about every DTS thread as though I don't really own a true DVD or a true home theater system unless I have DTS, and DVDs are just so-o-o sub-par if they don't have a DTS track, and it's unconscionable that I don't see it that way because DTS is just so-o-o superior, and DD even at its highest bit rate is just so-o-o inferior, and this tonal quality is so-o-o much clearer only with DTS, and that tonal quality is so-o-o much clearer only with DTS, so we should put every effort into DTS because those who don't listen to it will never understand, so to hell with 'em, let them suffer with Dolby ProLogic so we can reap the benefits of our so-o-o superior DTS system, blah, blah, blah, yackety smackety. It gets old quickly.

You know what? Legolas' arrow whizzing by in the distinct right-rear channel and the Horn of Gondor blaring in the distinct left-rear channel sound pretty damned impressive to me as do numerous other instances in numerous other movies that effectively use DD 5.1, and it's infinitely better in my opinion than two-channel stereo.

Ah, but if he doesn't bother to tell us the results, did the test really take place?

ROOGS! You Rascal!!!

All DTS recordings (I see no qualifications here)? Including the numerous recordings that used 16-bit masters? If a 16-bit PCM (master) recording has these "harsh" highs, then how can DTS encoding of this recording transform them into something "silky smooth"? This seems to suggest that DTS isn't in fact accurately reproducing the source, but actually improving it. That's an argument I've never heard before (at least not one seriously mooted)!

I'm not touching the use of analogue "smoothness" vs. digital "harshness" in a DTS vs. Dolby Digital discussion with a ten foot pole. I don't have a set of bass-enhancing crystals or audiophile-grade masonry bricks, so I'm not qualified to comment.


Try Labyrinth (original release), but this sort of comparison wouldn't reveal much I suspect.


And some also heard DTS with no pre-conceived expectations (this was at a time when virtually no-one had even heard of it) and thought to themselves "That's it?". This was also at a time when genuine comparisons were difficult, and when they did occur notions such as mastering differences, re-equalisation or dialog normalization weren't even a consideration.


This is certainly true, but it has no bearing on a DTS discussion. The comparative scale in the DTS debate is much smaller.

I can respect your opinion and preference for DTS, and it's clear these opinions are strongly held. However the basis of this opinion, other than your own ears, seems to be pure (and often uninformed) speculation and invalid/inappropriate comparisons on your part.

As for the original question, given the current mastering norms and assuming a properly prepared Dolby Digital soundtrack is provided, I would be perfectly willing to lose a DTS soundtrack. Not so I don't have to change a disc (a few seconds to change a dics is nothing really), but to ensure picture quality wasn't unnecessarily compromised by redundant data consumption.

Adam

Roogs,

excellent work. Much thanks.

I'm certain that you're right...that "other processing" aside from the pure issue of codec scheme comes into play with many of the differences folks hear with production-DVDs.

1. 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).

2. 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). I've actualy heard of cases where technicians reduced bit-depth to 16-bits prior to DD encoding to "reduce dynmaic range"! No kidding folks...

3. 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.

All 3 of these items are non-codec related yet could be real-world reasons why some audible differences exist.

-dave

Thanks Roogs, but can you clarify a couple of things?
Are you saying the difference between DD & DTS or a difference between a three?
Could you expand on what those anomalies were?

Did the listeners know which was which beforehand or was it a blind comparison?

You also mentioned it depended on the source material(music and movies)and amplitude. Could you please expand on that, as well?

DJ

Yes, regarding thos "anomalies"...do tell...

Roogs, thank you very much for sharing this with us.

I have never been in a position to conduct a controlled experiment and I appreciate those who take the time to do so.

And my sincere thanks.

My suspicion (without knowing) has always been that DD mixes are more often trying to be all things to all people (meant to satisfy casual listeners who are using their TV speakers for sound, for example), while many DTS mixes make no such concessions. A part of the reason for this may be that DD (or PCM) is a requirement for DVDs, while DTS is not (and therefore is under no implicit obligation).

It this turns out to be the case (and you got your wish that all DVDs had DTS), it might turn out that DTS would make many of the same compromises (that I speculate) are made by DD.

Or, be careful what you wish for…

Thanks again, Roogs.

Amen to that. There is no reason to mix for the lowest common denominator.

DJ

Incidently, I lurk at some pro forums and it seems like there is no consensus within that community just like here.
Opinions run the gamut from no noticeable difference to real and noticeable, but not significant.

That falls in line with what I would expect. They are both lossy, after all.

Just out of curiosity, are different masters used often and is the work on both often done at the same time in the same studio, in your experience?

Thanks for your candor; I understand if you can't answer some questions. It's a treat for us consumers to be able to interact with someone in the industry.

DJ

Roogs,

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. For this reason THX told me they encourage disc producers to include a separate 2.0 mix so the 5.1 can be left in its original state (one of the reasons he told me DTS often sounds better...that 5.1 DD mixes are often altered...including some that they've certified when no 2.0 track was present).

Sounds like they are not aware of meta-flagging to finess the down-mix process in such a way to leave the 5.1 mix unmodified for uncompromised 5.1 playback. Either that or the reps I talked to didn't have proper understanding of what their company did...though they sounded very technically informed.

I suspect that you and the mastering folks you work with are better educated about many of these things than most. I mean...every day we get DVDs with audio that is unnecessarily compromised by major studios (4.0 audio on Hello Dolly is severely noise-reduced which has removed all highs and musical detail) so I have a hard time just "trusting" that everyone out there knows what there doing. Not to mention all the "horror stories" I hear from industry folks who tell me confidential details about specific audio-muddling on some *very* major titles by some *very* major labels.

Seems like you win some and you loose some as far as DVD-audio mastering quality goes. Hopefully the "less is more" philosphy of audio mastering that you clearly understand will start to gain ground. I think lots of guys think the more dials the better (the "this one goes to eleven" mentality). If live-two-track stereo recording from the 1960's are any guide...clearly the less we do to the sound the more incredible it can be.

-dave

Very interesting Roogs—I intuitively thought the opposite.

I did, too. I thought that DTS would actually come out as the winner with at least some noticable advantage.

I think that as a necessary precaution, I need to bookmark Roogs' post. I'm sure that it will be needed in the future.

Or could it be that Roogs has finally - finally - brought an end to the endless go-nowhere DD/DTS debates on HTF (actual DVD mix differences not withstanding) since his statements are the probably the most clear cut that we've head?

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Na-a-a-a-a-a-h. :p)

Well John, you might want to reread Roogs’ first post where mentioned that his findings made no difference in anyone’s opinion. I fully expect that to be true as these threads come and go from time to time.

Before anyone on any side of the debate tries to run with Roog's findings....keep in mind what he's demonstrated:

He's demonstrated that being fed a 24 LPCM signal, that with no additional processing applied, DD at 448 and and DTS at 754 rate sounded "different" to many listeners but that these differences were difficult to qualify without an A/B/C test.

In other words, that tells us in the most pure form what the codecs sound like at those two rates, all other things being equal.

HOWEVER, rarely in practice are all other variables equal (though it seems that Roogs and those he works with seem to not be great offenders on this matter as they clearly are aware of these concerns). Sometimes times hi-bit 24 LPCM masters are decimated down to 16-bit prior to mastering for DD. Sometimes additional "options" in the DD software suite like dialog normalization are applied. Sometimes mastering engineers may feel the need to alter the 5.1 mix for 2.0 playback (though apparently this is less necessary than some industry folks have let us to believe given what Roogs has shared). 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!

If level-adjustment was performed either boosting the level for DTS encoding or reducing the level for DD encoding...that's digital signal processing that can affect the sound and tells you that, on at least one of those soundtracks, the master-LPCM tracks weren't just "dumped" into the encoder in pure form.

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.

It also indicates that the more variables that are kept constant between the mastering of the DD and DTS signals, the less difference one will likely hear between them.

-dave

p.s. So Roogs, can you whisper any DD/DTS titles that your team has been responsible for mastering?

Some of us reached this conclusion a long time ago.

M.

I had always put my inability to detect real differences down to inadequate equipment, including my ears, which may never have recovered from ill-advised living during the 60s.

And my skepticism as to discernible superiority I put down to my general disbelief on any commercial enterprise maintaining product superiority for extended periods.

Now, at least I can go back to no regrets on the 60s.

That's why I said, "Na-a-a-a-a-a-h."