Atmos vs 5.1

[stoopid]

Just so if I am understanding this correctly, if I make a 7.1 AVCHD disc using DTSMA with discrete info in each channel and give it to a friend who only has a 5.1 system, he will still hear all the information. Nothing will be lost. Correct?

That's my understanding.

 

[Sal1950]

Nothing is thrown away. In DTS HD MA 7.1 the rear information is already in the surround channels. So to play in 5.1 the rears are simply discarded, whereas to play in 7.1 the rears information is subtracted from the surround channels to derive what is played in the surround speakers. Nothing is lost. It's the same kind of scheme that is used by Atmos for the height data.

OK, that's not the way I read your original post, very confusing this stuff.

For example, with DTS HD MA to go from 7.1 to 5.1 the rear channels are discarded because everything has to be in the 5.1 core which includes the surrounds.

 

[Sal1950]

https://www.thestereoshoppe.com/

I’ll be having my dear old 7701 for sale in a week or so.

I don't see any prices listed?
Anyhow, hope you get a good price, the AV770x have always been great pre-pro's.
I owned a 7701 for a long time till I sold it to buy the 7703, I wanted Atmos and other things.
A friend of mine on another site has my ole 7701 and its still running perfectly.
Well built components!

 

[barfle]

I don't see any prices listed?
Anyhow, hope you get a good price, the AV770x have always been great pre-pro's.
I owned a 7701 for a long time till I sold it to buy the 7703, I wanted Atmos and other things.
A friend of mine on another site has my ole 7701 and its still running perfectly.
Well built components!

I was quoted $2879. Undoubtedly plus tax, and I'd be surprised if I get to take it home today. But I'll find out in a couple of hours. First, I have to log down all my settings in my 7701. I've personalized it quite a bit, and I don't want to have to go through all that "try this, try that" again. Hell, it's taken me a decade to get it JUST RIGHT!

 

[Sal1950]

I was quoted $2879. Undoubtedly plus tax, and I'd be surprised if I get to take it home today. But I'll find out in a couple of hours.

That sounds good for a "new in sealed box" unit, be sure.

First, I have to log down all my settings in my 7701. I've personalized it quite a bit, and I don't want to have to go through all that "try this, try that" again. Hell, it's taken me a decade to get it JUST RIGHT!

As to the rest, good luck. So much has changed I doubt much will transfer.
No harm in trying.

 

[Methuselah’s Grandpa]

You know none of this is done on the fly right? They are all complete mixes.

Isn't it done on the fly though? There can't be 4 complete mixes, just look at the size of the audio.

Those different sub-streams (stereo, 5.1, 7.1, Atmos) are merely instructions on how to unfold or unpack the audio to fill out the maximum number of speakers supported by the player & hardware being used at the time. There isn't a separate stereo mix + a separate 5.1 mix + 7.1 mix, etc.

The instructions on exactly which audio elements are included in the 4 different sub-streams is not done on the fly but the way in which the sub-streams work, by only unfolding or unpacking certain elements, & then subtracting those where needed, ...is done on the fly; ...this is what makes TrueHD so space-efficient.

 

[barfle]

Isn't it done on the fly though? There can't be 4 complete mixes, just look at the size of the audio.

Those different sub-streams (stereo, 5.1, 7.1, Atmos) are merely instructions on how to unfold or unpack the audio to fill out the maximum number of speakers supported by the player & hardware being used at the time. There isn't a separate stereo mix + a separate 5.1 mix + 7.1 mix, etc.

The instructions on exactly which audio elements are included in the 4 different sub-streams is not done on the fly but the way in which the sub-streams work, by only unfolding or unpacking certain elements, & then subtracting those where needed, ...is done on the fly; ...this is what makes TrueHD so space-efficient.

I doubt if the various languages you get on DVD and BD are "done on the fly."

If your deck or AVR processes tracks down from 7.1 to 5.1, that's done on the fly, as is Atmos decoding. There is also a possibility of "upmixing" that would be done on the fly. But I'm pretty sure if you select a track from a disc, it's going to be a separate track.

 

[LuvMyQuad]

Isn't it done on the fly though? There can't be 4 complete mixes, just look at the size of the audio.

Those different sub-streams (stereo, 5.1, 7.1, Atmos) are merely instructions on how to unfold or unpack the audio to fill out the maximum number of speakers supported by the player & hardware being used at the time. There isn't a separate stereo mix + a separate 5.1 mix + 7.1 mix, etc.

The instructions on exactly which audio elements are included in the 4 different sub-streams is not done on the fly but the way in which the sub-streams work, by only unfolding or unpacking certain elements, & then subtracting those where needed, ...is done on the fly; ...this is what makes TrueHD so space-efficient.

If that were the case you wouldn't be able to rip them individually. And you certainly can rip them. I use makeMKV. Make MKV doesn't have the capability to do any of the manipulation you describe, but it delivers full complete rips that you can then easily convert to FLAC if desired.

A bluray has a lot of storage available. About 25 gig per layer. And i think most commercial discs are 2 layer.

The thing that makes TrueHD efficient is that it's basically MLP with a different name, the same lossless but space saving codec used on DVDAs The 5.1 AC3 stream is lossy and takes up very little space. The stereo track Is typically 24/48. Again not all that large.

 

[Methuselah’s Grandpa]

I doubt if the various languages you get on DVD and BD are "done on the fly."

If your deck or AVR processes tracks down from 7.1 to 5.1, that's done on the fly, as is Atmos decoding. There is also a possibility of "upmixing" that would be done on the fly. But I'm pretty sure if you select a track from a disc, it's going to be a separate track.

I probably replied to LuvMyQuad needlessly as it seemed like in some of his posts after the one I replied to, he didn't seem to be saying that he thought that the TrueHD sub-streams are actually complete, separate audio streams.

Regarding your comment on the different languages, ...that's completely different. Those are indeed, separate audio streams, ...the "on-the-fly" comments that LuvMyQuad was talking about are "sub-streams" of the TrueHD codec

 

[Methuselah’s Grandpa]

If that were the case you wouldn't be able to rip them individually. And you certainly can rip them. I use makeMKV. Make MKV doesn't have the capability to do any of the manipulation you describe, but it delivers full complete rips that you can then easily convert to FLAC if desired.

A bluray has a lot of storage available. About 25 gig per layer. And i think most commercial discs are 2 layer.

The thing that makes TrueHD efficient is that it's basically MLP with a different name, the same lossless but space saving codec used on DVDAs The 5.1 AC3 stream is lossy and takes up very little space. The stereo track Is typically 24/48. Again not all that large.

If I take a 3-min song & convert it to 5.1 ac3, TrueHD stereo, TrueHD 5.1, TrueHD 7.1, & TrueHD Atmos, ...& then "mux" those all together, ...they would take up significantly more space.

 

[LuvMyQuad]

If I take a 3-min song & convert it to 5.1 ac3, TrueHD stereo, TrueHD 5.1, TrueHD 7.1, & TrueHD Atmos, ...& then "mux" those all together, ...they would take up significantly more space.

Sure. But a full album still fits easily on a bluray. The TrueHD 7.1 and Atmos are the same file. A 5.1 True HD stream may or may not be included. And nearly all the streams are losslessly compressed. There sometimes is a stereo LPCM stream. And even video sometimes.

 

[kfbkfb]

AFAIK, for physical media, a separate DD (up to 5.1) soundtrack is required by Dolby Labs for TrueHD (which may also contain Atmos) soundtracks.

On my bedroom system, the soundtrack goes -> Atmos -> TrueHD -> DD 5.1 -> Dolby Surround(done in my Sony Blu-ray player), I'm not sure why a separate stereo downmix of the Atmos soundtrack on a Blu-ray disc would be needed.


Kirk Bayne

 

[LuvMyQuad]

AFAIK, for physical media, a separate DD (up to 5.1) soundtrack is required by Dolby Labs for TrueHD (which may also contain Atmos) soundtracks.

On my bedroom system, the soundtrack goes -> Atmos -> TrueHD -> DD 5.1 -> Dolby Surround(done in my Sony Blu-ray player), I'm not sure why a separate stereo downmix of the Atmos soundtrack on a Blu-ray disc would be needed.


Kirk Bayne

I think the separate LPCM tracks you find sometimes are dedecated stereo mixes, not downmixes. Of course sometimes there are also dedecated 5.1 mixes, They can be True HD or DTS MA.

But all substreams in the Atmos TrueHD stream are algorythm based fold downs derived at the time of mixing. I've heard others say the mixer can adjust parameters on that process.

Aren't the DD and the Dolby Surround the same thing?

 

[SeeMoreDigital]

If I take a 3-min song & convert it to 5.1 ac3, TrueHD stereo, TrueHD 5.1, TrueHD 7.1, & TrueHD Atmos, ...& then "mux" those all together, ...they would take up significantly more space.

And don't forget that all those lossless Dolby TrueHD tracks will have to include a mandatory lossy Dolby Digital 'core' (or whatever people prefer to call it) in order for the disc to be Blu-ray spec compliant

 

[Owen Smith]

But all substreams in the Atmos TrueHD stream are algorythm based fold downs derived at the time of mixing.

I'm not convinced there are ever more than one True HD substream, the 7.1 mix. That can then be folded down at playback to 5.1 or stereo as required by the True HD decoder. The AC3 substream and if relevant the Atmos substream will be present.

 

[Owen Smith]

And don't forget that all those lossless Dolby TrueHD tracks will have to include a mandatory lossy Dolby Digital 'core' (or whatever people prefer to call it) in order for the disc to be Blu-ray spec compliant

Indeed, which is why I'm surprised that some discs also have an AC3 track you can select from the menus. That means two AC3 tracks on the disc, why?

 

[Methuselah’s Grandpa]

For anyone curious, I created multiple mixdowns of a song that is 5:04 for the sake of comparing the sizes:

TrueHD Atmos = 227MB
---------------------------
TrueHD stereo = 62MB
TrueHD 5.1 = 152MB
TrueHD 7.1 = 199MB
AC3 (640 kb/s) = 23.1MB

 

[kfbkfb]

Actually, I like the DD 5.1 (from Atmos) downmix on the SDE ABC album better than the DTS mix

The DD (up to 5.1) downmix to Dolby Surround dates back to DVDs, how to get a DS encoded output from the DD (up to 5.1) mix on the DVD without using up space for a separate DS encoded soundtrack, my Sony Blu-ray player(s) can be set to downmix to DS from both DD and DTS (up to 5.1).


Kirk Bayne

 

[himey]

I'm not sure why a separate stereo downmix of the Atmos soundtrack on a Blu-ray disc would be needed.

DAW output to stereo of the original session files may sound different and possibly more consistent than what various players and receivers may do to an Atmos TrueHD track downmixed to stereo. Also, and more importantly, they can promote a new stereo mix.

 

[Owen Smith]

AC3 (640 kb/s) = 23.1MB

The AC3 inside Atmos tracks is rarely that high bit rate, I've seen plenty of complaints about it being less eg 448kbps as on DVD.