Home Theater Dynamic Range Considerations - Page 2

While Amirm's link and point are valid, psychoacoustic responses as per frequency only change the numbers a bit. IN the real world, you simply want backround noise as low as possible. Whatever your sources dynamic range, its pretty set and unchangable, as so are the maximum levels your willing to listen at. In general, the maximum dynamic range you will hear in a given situation is going to be at the loudest level your willing to listen to. Whether that allows you to hear the full range of the dynamic source or not becomes irrelevant if your noise floor and source dynamic range are fixed.

I said the source was unchangeable. Certainly you can augment the dynamic range after the source.

For dedicated audiophile 2ch stereo, I dont advocate processors of any kind. Most problems in this scenario are caused by the room and therefore can be fixed by the room without degrading the signal path. But for 5.1/7.1 HT surround, thats a different animal entirely IMO. Sure, degrading the signal path is never a good thing, but the room (if done right) plays a smaller part and getting all the channels to do what they are supposed to do becomes paramount.

I guess I come from the standpoint of movie listening demanding one thing and 2ch stereo another. Music on a HT system usually suffers a bit compared to a optimized 2ch setup audio only given the broader needs of HT. But I imagine music can still sound very good.

Most people over 40 would be shocked at their actual high-frequency hearing loss.

On the other hand, 99% of the content of recordings is below 5 Khz.

People who go on about peaks and resonances at 12 Khz or some such high frequency affecting the sound quality need to listen to some music with everything above 5 Khz filtered out.

You can filter out everything above 5 Khz, and most people won't be able to hear the difference on 90% of all music.

I'm having this same problem. I have absolutely no problem with normal 5.1 audio or TrueHD. It's DTS-HD Master Audio that's the problem. I just tried to watch The Rocketeer. The dialogue will be fine and the effects way too loud or the effects will be fine, and I'll have to strain to hear the voices. Please don't tell me it's the speaker placement, because it's not. Except for the rear surrounds, the speakers appear to be set up pretty much like it shows in the manual. I have this sound problem with Jurassic Park, as well. Which sucks, as Jurassic Park and Rocketeer are two of my favourite movies. In my player, I can set it up so that something called HD Audio is set to "Mix", which apparently mixes the movie audio so that you can hear menu sounds as well as the other audio. This enables the DRC settings on my receiver which are Off, Low, and High. But I really don't like to do this as the sound doesn't quite have the bass and punch as streaming the straight HD audio. The good thing is that I can hear the dialogue just about perfectly. I just don't get why Rocketeer even has DTS-HD Master Audio. It came out before DTS existed. Now, Jurassic Park I can understand. It was the first DTS movie.

it's not the box, its the contents. DTS-HD is just a way to put whatever the movie's producers and sound team mixed onto the physical medium, and it doesn't change the mix to put it on in DTS or DD lossless or in lossy DTS or DD (or in PCM for that matter). If you don't like the DRC, then your choice is to turn up the center speaker.

everytyhing is recorded in linear PCM, and mixed in linear PCM, so what particular lossy or lossless technology might have been available at the time the mix was done is irrelevant. You take the PCM and either put it on the disk (lots of room used) or you use one of the Dolby or DTS products. Pretty much just like you can appropriately put a Beatles record on CD although they stopped recording decades before there was digital recording gear.

^^ +1

It's the mix, not the data compression codec. You'd get the same results with those two movies if they'd been encoded using TrueHD or put on the disc as multichannel PCM.

No. The center channel is the problem. If it were just the dialogue that was in the center channel, I COULD turn up the center channel. But it's more than just dialogue in the center. The Dolby 5.1 and the DTS-HD Master Audio of Rocketeer sound completely different. In the 5.1, I can hear the dialogue of the movie just fine over the effects. But with the DTS-HD, it's either have the dialogue where you can hear it and the effects blowing out your eardrums, or have the effects at a normal level and the dialogue so low that you practically have to put your ear against the speaker to hear anything. I just wish they would have a normal 5.1 option on movies. There IS that option, but not in a language that works for me.

No. It IS the mix. I can listen to TrueHD just fine. The dialogue is loud enough without being crowded out by the effects with TrueHD. But there is just something strange about DTS-HD Master Audio.

Perhaps you don't understand that dts-MA and TrueHD are lossless data compression codecs whose sole purpose is saving space on the disc. If you feed the same soundtrack into both encoders, the same soundtrack (bit-for-bit) will come out of both decoders at the other end. These data compression codecs don't change the mix any more than a zip file changes fonts in a document.

You have experienced mixes that don't work for you that just happen to be encoded using dts-MA and mixes that do work that just happen to be encoded in TrueHD. But, it's the underlying mix that's the issue, not the data compression codec.

Think about it - how can two lossless codecs produce different outputs when fed the same input? If the outputs are different, one of them isn't lossless.
Edited by BIslander - 2/28/13 at 1:25pm

sorry, there's just not the codec. Unless the person encoding into DTS-HDMA messes up, what gets into the codec is what was mixed on the mixing stage (or remastered elsewhere). Moreover, neither the codec nor the person in charge of the encoding can change the levels of items like the dialog in the mix. Once it's mixed into a channel, the channel is what it is. There's not a way to turn up the sound of a lawnmower in the center channel if there are 10 other sounds there at the same time. Their volume controls are just like yours and turn up everything in the channel, or turn down everything in the channel (leaving aside some tweaking that may be possible sometimes with EQ to bring out some aspect of the mix more prominently during the mastering process, which is still not something the DTS HDMA can change). Once you mix down, you lose control over individual mix elements, and encoding for release on bluray is WAY after the mixdown occurred.

Some movies are mixed in ways that annoy folks.

In fact, frequent contributor Filmmixer has talked in the past about deliberately mixing dialog low in battle scenes in at least one episode of the Pacific, because the director was willing to trade off intelligibility (at least potentially) for a more you-are-there experience. Encoding that track to DTM-HDMA simply will not change that deliberate mixing decision. Can't.

Imagine ripping a cd to MP3. You cannot turn the vocal up or the guitar solo down during that process, because they're already fixed in level by the time the sound gets to the cd. It's really the same thing . . .

I agree with everything you just said. DTS-HD Master Audio and Dolby seem to be mixed differently.

Again, the mixing is long since done by the time the soundtrack is encoded on the Blu-ray disc. If Jurrasic Park were released using TrueHD, it would just the same as dts-MA.

Spottedfeather - the vast majority of Blu-rays have dts-MA tracks. Do you find the mixes to be bad on all or most of them? Or, is it just a handful like the ones you mentioned?

Less than half of the blu-rays I have have DTS-HD Master Audio. I find all DTS-HD Master Audio mixes to be bad. Not all to the same degree, mind you, but still horrible. For example, Back To The Future. The dialogue in that is closer to normal that every other DTS-HD track I've heard. Though in BTTF part 2, there are some off screen voices that can be a bit hard to hear.

The only DTS-HD Master Audio mixes that I can stand are Beauty And The Beast, Changeling, the 2 Toy Story movies, the Scream movies, and Robocop. Those are all on the very edge between "can listen to comfortably" and "normal DTS-HD nonsense." With the titles I've mentioned, the dialogue isn't as bad as most DTS-HD mixes, but they are a lot closer to what I can stand. The other blu-rays I have either are completely, horribly mixed, or have the original theatrical audio incliuded. If a movie was released in stereo, mono, or whatever, that's how I want to listen to it. It's mainly the movies that have a lot of music and effects that DTS-HD causes a problem in. For instance, Rocketeer and Jurassic Park. For some reason, I don't have any problems with so-called kids movies that use DTS-HD. The dialogue is always easy to hear over the rest of the soundtrack.

Thanks. That pretty much clears it up. Some movies sound fine when encoded with dts-MA and others don't. But, as you continue to reject the obvious conclusion that it's the mix and not the codec, perhaps you can explain how lossless data compression/decompression applied long after a soundtrack is mixed can change the way it sounds.
Edited by BIslander - 2/28/13 at 6:07pm

I didn't say it was the codec. It's just been my experience that when they mix DTS-HD Master Audio, they put the voices far too low. I never said that lossless data compression/decompression applied long after a soundtrack is mixed wouldn't change the way it sounds. What does that have to do with anything ?

That's the only issue!

THERE IS NO SUCH THING AS A DTS-HD OR TRUEHD MIX. The movie is mixed creating a soundtrack that is recorded as multichannel PCM. That soundtrack can simply be placed on a disc, an exact copy of the original soundtrack. But, multichannel PCM takes up a lot space that studios would rather use for special features. So, they use lossless data compression/decompression codecs such as TrueHD and dts-HD Master Audio to save space on the disc. They are called lossless because the decoded output is identical to the original PCM soundtrack. Identical. No bits are changed. None of them. If the TrueHD version is identical to the original and the dts-MA version is identical to the original, then the TrueHD and dts-MA versions are identical to each other. In math terms, if A=C and B=C, then A=B.

Put another way, TrueHD and dts-MA are just like zip files, which only serve to save space and do not change the zipped up content one iota.

If you think any of this is incorrect, please explain what lossless data compression codecs do. Or, what else do you think happens with dts-MA and TrueHD beyond data compression?
Edited by BIslander - 2/28/13 at 6:42pm

Then explain why I have absolutely no problems with TrueHD and Dolby 5.1 but have massive problems with just about every DTS-HD Master Audio ? It seems as though, when they mix the audio for DTS-HD Master Audio, the voices are way too low. Why doesn't that happen with TrueHD or Dolby 5.1 ?

You keep talking about mixing for TrueHD or dts-MA, even though several of us have explained more than once that such a notion is incorrect.

No one mixes the audio for TrueHD or dts-MA. They mix to produce a soundtrack. TrueHD and dts-MA get involved later, when the track is put on the disc.

I'll answer your question: you hear differences because the movies were mixed differently. They would sound the same no matter which codec is used to put the track on the disc.

Now , please answer my question: what do TrueHD and dts-MA do beyond data compression that would change the sound?

My guess would be your receiver is auto detecting Dolby True HD and applying dynamic compression, but DTS HDMA doesn't trigger the automatic applying of dynamic compression. Therefore you are listening to DTS HDMA with full dynamic range but listening to Dolby True HD with compression applied and drawing the conclusion that DTS HDMA is crap, which is probably due to your room/playback volumn not being optimised for the intended full range of the soundtrack.

There was lots of talk when Ironman 1 originally came out on BD that the audio was weak and had little dynamic range. Turned out the Dolby True HD audio triggers certain brands of receivers and prepros to automatically apply dynamic compression, once the setting was turned off the Ironman audio track came to life. The thing is once the receiver/prepro is turned off, it will automatically revert to applying dynamic compression next time it is turned back on and detects a Dolby True HD soundtrack, so dynamic compression has to be turned off every time you watch a Dolby True HD encoded BD if you want full dynamic range.

Yeah, my receiver automatically detects TrueHD. DTS-HD Master Audio, etc. But it doesn't do any dynamic compression until I tell it to. It's off by default. For DTS-HD, the option for dynamic compression doesn't show up. It only does that for TrueHD and Dolby 5.1 (4.0, 2.0, mono) formats. And BIslander, I don't quite know how to answer your question. If the mix for a soundtrack is the same, I don't get how I can watch a movie with Dolby 5.1 and hear it just fine, but then watch that same movie in DTS-HD Master Audio and I can rarely hear the voices properly....

The Onkyo receivers that had the Ironman problem powered up with DRC set to Auto. Auto does not turn on DRC. Rather, it means DRC will be engaged if the disc instructs it to do so. And Ironman is the only disc known to do that. Now, it is certainly possible that Spottedfeather has manually set his receiver to use DRC, which would explain why he can hear dialog better with Dolby encodes than with DTS.
Edited by BIslander - 2/28/13 at 10:13pm

What movies would those be? DD 5.1 is a lossy codec while dts-MA is lossless. So, they are not the same. The apples to apples comparison is TrueHD to dts-MA. Are you saying you watch a DVD with a DD 5.1 track and then watch the Blu-ray with dts-MA? Those won't be the same. There are precious few discs that have dts-MA tracks along with a Dolby alternative, either DD 5.1 or TrueHD. As suggested over at Blu-ray.com, try the 30th anniversary edition of Close Encounters, which has both lossless codecs, presumably from the same master.

btw, do have DRC engaged on your receiver?

Oh ok, I stand corrected then, apologies all. I thought "auto" meant it was actually applying DRC "automatically". Thanks for the explanation.

Anyway spottedfeather must have some form of compression going on automatically for Dolby TH sources, and not DTS HDMA sources, as agree there should be no difference in the two.