Dolby TrueHD vs. DTS-HD Master Audio

Hi Kain, In my opinion, the main difference is who is receiving the royalties.

They are simply two competing formats, and I don't believe one is better than the other. If there are more DTS-HD Master Audio discs available than Dolby TrueHD discs, it is likely more for business reasons than technical reasons.

I wouldn't count on them being equal to the audio track that you hear in the theater, however.

Many studios will do a mix for the theatrical release, and then do separate mixes for DVD and Blu-Ray. I'm not involved in the audio end of the business, so I don't know exactly why, but I suspect it has to do with the expected capabilities of the playback equipment (with theaters being held to a higher standard).

I would rather suspect they try to direct people to theaters by using lower grade soundtrack on disk. BD has enough capacity to let them put multiple sound mixes including theatrical one.

As noted, they are both lossless so the quality matters not. Studios pick one or the other sometimes on technical reasons. That being how much peak bandwidth one may take vs another (in lossless compression bandwidth cannot be controlled). More often than not however is how proactive the vendor is in promoting their technology through joint promotions, free gear, etc. Other times the post production house has a favorite so they go with that.

A good question is why there are two of the same thing. Anyone know why? I voted for them so I will give the answer once I hear people's guesses.

Two companies, two lossless formats. When decoded, the same soundtrack compressed using TrueHD or dts-MA will produce identical PCM.

Theaters almost always use lossy soundtracks, not lossless. In fact, DD 5.1and DTS were developed because mutlichannel PCM soundtracks are too big to fit on a film.

Theatrical playback is designed for very large spaces where the track is played at reference. Remixing for home theaters is often done to adjust for the smaller space and lower volume levels.

Unfortunately, not always true. On occasion the DTS track has been "remastered for home use", or words to that effect, whatever that means, but the Dolby track has not. It's mostly an issue of Re-EQ for home systems. It's happened on Dolby tracks too, but the problem is, there's often no indication of which track has had what done to it, and they both may have been remixed for home use. Anyway, the path from the master to the specific track may not be equal. True, and quite accurate, but these days incomplete. Digital Cinema has within it a variable channel count, up to 12 channels of 24bit lossless channels. The data is compressed, but not bit-rate reduced. It's up to the theater to choose the channel count, but also the film itself. A few have been released in Dolby 7.1, but not many. The point is, Digital Cinema houses present lossless audio.

Yes, hence the problem alluded to above. It's not that they're remixed, it's that we don't know if they are or not. In the early days of Laser Disc and DVD, there was no remixing (actually re-mastering) going on, and hence the need for things like THX ReEQ. Now that remastering is done, we might need ReEQ, or we might not. There's no way to tell other than to listen. If it sounds too bright, punch in the ReEQ. If it sounds good, leave it off. Too bad the choice has to be up to a rather uneducated judgement call, though.

Perhaps you missed the bolded part of my post. A track that has been remastered for home use is not the same soundtrack. Here's the point as it relates to the topic of this thread: the lossless codec itself has no bearing on the output. If you start with the same soundtrack, the decoded output of both TrueHD and dts-MA will be identical. Again, see the bolded part of my post, which I included because there are a small number of theaters equipped for lossless audio. Some posters earlier in this thread seem to be under the impression that theatrical audio is generally better than BD when, in fact, the opposite is usually the case.
I'm not sure what point you are making here. My comment was a response to posts like the one in #4, which speculates (incorrectly, I think) about why a movie may be remixed for home release. It's not that theaters are held to a higher standard. Rather, theatrical and home environments have different requirements.
Edited by BIslander - 11/10/12 at 10:58pm

I need to disagree. Theaters are held to a higher standard. There is no standards for the home, yet SMPTE and THX have both published standards that theaters are meant to adhere to.

Correct.
No. It is due to the different circumstances at home: movies are played back at lower volumes.
DTS is favored over TrueHD for the simpler encoding and QC'ing process. That means time saved, and thus cost reduced.

There are often two vendors for things like audio and video codecs that are licensed into optical disc standards so that a) neither vendor has monopoly control, and b) if one founders, the other may take up the slack.
That happened in the laser disc days, but ever since studios and post houses have had their own people running the encoding tools, whatever is done to remaster for home release is the same for either codec.
The audio is LPCM, not lossless, and not compressed.

I think you may be both right. ;-)

We do know that mastering for theaters and home release is often different.

We know that some home theater setups may have higher performance capabilities than the average and maybe just about all commercial theaters, and that some media seems to try to exploit this.

AFAIK the nature of standards for things like mixing and mastering cannot be rigidly evaluated, so therefore in some sense compliance is semi-voluntary.

We need to remember that for many, probably most releases, the home market is where the money is.

So we have two lossless codecs, yet some users are reporting significant differences in bass, loudness, and dynamic range between the two. Care to enlighten us how that can be?
If "lossless" means no loss of data, then LPCM would be lossless, would it not? It's raw PCM data, so the process of recording and reproducing would not involve data loss. Am I missing something, or are we just tied up in a classic AVS Forum semantics knot? If "compressed" in this case means "more efficiently packed, no data loss", wouldn't that apply? Compression of PCM data can save up to 30% in storage space. I was under the (possibly mistaken) impression that was done for Digital Cinema releases. It would save space on the distributed HDD.

The only thing that even has a chance of being worse is circumstantial evidence.

[\[eople do imagine lots of things. To the best of my knowledge, the only likely difference is that it seems more common to apply dialog normalization with Dolby than with DTS although it's available for both. A 4 dB level difference could easily be enough to make the bass seem different. But it's not entirely that difficult to turn up the volume control to account for the dialnorm offset.

Lossless is generally used as shorthand for losslessly compressed. Since PCM is not data compressed it is not common in the industry to refer to it as lossless. AFAIK.
Edited by JHAz - 11/11/12 at 7:13pm

Well, if there are no home theater standards, it is not possible for theatrical standards to be higher (or lower) than something that does not exist.

Meanwhile, back to the context of the discussion... the earlier posters seem to be under the impression that studios consciously downgrade the quality of the audio for home releases. I do not believe that is the case. Unlike theaters, BDs feature lossless tracks and remixing is usually done so that the soundtracks work better in a home environment.

Having read through hundreds of threads and countless posts on this subject over the years, the vast majority of such observations are actually comparing different soundtracks from different movies, not the same soundtracks using the different codecs. There are only a handful of discs that have the same track encoded both ways.

Beyond that, home comparisons are rarely properly controlled - sighted and not level balanced.

Plus, many TrueHD releases have their volume lowered by dialog normalization and it's a natural tendency to equate louder with better.

+1

To a person with some time on their hands, a search for participant FilmMixer's posts on the issues may be helpful. While he does not remix many of his movies (at least last I saw) the changes he makes generally relate to minor deviations to keep dialog or surround information appropriately audible at the lower SPLs typically used in home. Not broad changes to dynamics or t obass extension or anything like that. Of course to the extent Sony or others have started outsourcing a remix to third parties, our knowledge of the changes will be less complete. But I also suspect the third parties deal with a few dozen individual stems/tracks, rather than the several hundred (thousand?) that were originally used to create the mix . . .

Ok, I have to concede that all of that is true.

One of the "higher standards" I was thinking of when I made my post was that the sound mixer would assume that the volume in the theaters would be at reference level. So he/she would have more leeway when it comes to setting the levels of quieter audio. That same quiet audio, if set to the same relative level, might be too low at home if the volume is not turned-up enough. I suspect that things like this are what motivate the studio to create separate mixes.

I may be completely wrong here and I'm open to any correction... But I thought that THX standards no matter if for the theater or the home were to produce reference levels in different sized venues or rooms. For at home there is THX I/S certified, Select, Select2, Select 2 Plus, Ultra, Ultra2, and Ultra 2 Plus. And yes I understand that some of those standards pertain to speakers and some to receivers or amps.

But isn't the THX standard that a system needs to produce reference levels with Bass down to 20hz -6db and Treble up to 20khz -6db and then +/- 6db across the rest of the freq range? Of course receivers speakers and amps need to be sized differently and all that to produce those levels in different sized home rooms and also commercial theaters.

Sounds right to me.
I don't know the specific response requirements, but for THX speakers it probably pertains to the manufacturer, as there is no THX EQ certification requirement for home systems. Cinemas are supposed to hit the X-curve.

Not sure how this relates to the discussion. At home, even THX users typically play movies -10 dB, per a survey conducted by Tom Holman. So having "reference level" capability, and using it, are two different things.

Isn't that what tools like Dolby Volume or Audyssey Dynamic EQ + Dynamic Volume are supposed to do for us? If I want to watch a movie at something below reference level, I should be using processor features like those to adjust and keep things sounding right. If the mixer is doing the same thing, aren't I applying the same corrections twice? He has no idea what volume level I'll play back, so he can't possibly apply the right corrections at his end. It seems like it can only be done at my end. Or am I way off base here?

Hi Pitviper,

But he cannot assume that the listener has Dolby Volume or Audyssey Dynamic EQ + Dynamic Volume (I don't). Indeed, most listeners will not (at least not yet). So yes, there may be some redundancy here, and the same corrections may be applied twice, but that's better than applied not-at-all.

Also, my understanding is that Dolby and Audyssey apply their correction based on how high you turn up the volume. If you are up high enough, I believe they don't apply any correction. In that respect, Dolby and Audyssey are "dynamic" while the fruit of the sound mixer is "static".

Moreover, while Im not a particular fan of remixing for home, Dynamic Volume or Dolby volume can only operate on the mix as a whole. They cannot turn up just the dialog, if there are other sounds in the center channel, for example. So the results would differ. In my personal perfect world, they'd leave the mixes alone because I'm not unhappy with how DynVol works for me when I listen at different levels below reference . . . .

^^^ I agree. I think they should leave it up to the end user (us consumers) how we want to hear it. So just leave it as the same mix and we can adjust from there.

If you do not use DynVol, you are in the same boat as 99.9% of users who play the content directly. That means the studios are justified in making some adjustments to ensure good results under such conditions.
How would you, or the 99.9% of people who have no access to dynamics processing, adjust the soundtrack?

I just have a mid-grade AVR Onkyo 808 but even that receiver has all the THX stuff built into it. It also has Audyssey DynEQ and DynVol, THX Re-Eq and Re-Eq and Late Night. I used to use DynVol set to Light and I was only allowed to have it turned up to -44db for HDTV and -36db for moives. Now I have it set to Off and I'm allowed to have it turned to -32db for HDTV and -24db for movies when the wife is home. I personally think it sounds better and more natural having DynVol off even at levels so far below THX reference. Plenty of Bass and surround stage sounds good but not over powering.

So it seems like we are all happy with whatever is being done to soundtracks on their way home.

Which discs were filtered, and how do you know?