Atmos – Technical Question Regarding Backwards Compatibility

[Bonzo]

So we rented The Secret Life of Pets Blu-ray from RedBox last night and it’s what I believe to be the first disc we’ve gotten with Atmos on it. When we played the movie, I noticed almost immediately that there was very little, if any, sound coming from the surround speakers. I got up and put my ear next to the right side surround speaker. There was indeed sound, but it was very faint, not at all what should be coming out. And it appeared as that while I was getting at least some sound from the side surrounds, there was nothing in back. So I was getting very quiet 5.1, not 7.1. It also appeared that there wasn’t much truly deep LFE signal in the movie, something I find hard to believe. I checked the POP menu on the disc and the only English option was Atmos. I checked the speaker levels in the Blu-ray player and all was accurate. So I started thinking about what could be wrong.

[NOTE: I need to mention right now that since my old Denon receiver does not have HDMI, I currently use the Panny Blu-ray player to do the Dolby True / DTS Master surround decoding, and it sends those signals via 7.1 analog to my Denon, where I use the 7.1 analog inputs, and the Denon applies ZERO processing to the signal, except overall volume control.]

With this in mind, my first thought was that perhaps my Blu-ray player needed a firmware update. As it turns out, there was a new update put out in 2015. I didn’t have time to check my player yet, but I think I may be missing this update. I’m almost positive the firmware version I currently have is from the upgrade before, which was in 2012. But regardless, I’m thinking that this 2015 upgrade isn’t really going to matter for this particular issue, because anything done in 2015 was before Atmos discs even existed. I’m going to look into it further tonight, but I really don’t think it will fix this issue.

My second thought was, I wondered if this was an issue with the Red Box release of this disc? RedBox has been known to skimp on extras etc so I was wondering if they put on a “limited” Atmos only version on this disc. Is this even possible?

It was my understanding until last night that Atmos and DTS:X are supposedly fully backwards compatible formats. They were made this way so people with older processors and players could still enjoy their Dolby True and DTS Master without having to immediately upgrade just to hear what they had before. But in reading stuff last night and this morning, I can’t find much talking about my 7.1 analog situation. What I did find is that it appears there aren’t many people worried about being able to play Atmos discs to get 5.1 / 7.1 Dolby True, either via analog or HDMI. What there are is people worried that their old player won’t send the Atmos signal to their new processors so they actually get Atmos. (The logic being that “of course” a new processor is required for Atmos, but the question being do you also need a new player?). And the fix for that is, using HDMI, set the player to bitstream (not PCM), and then the new processor will play the full Atmos signal. Basically, the older player will send 100% of the unprocessed Atmos signal via bitstream using some technique that new processors will understand and “expand” it to full blown Atmos. I’m thinking that using the same sort of thought process, that perhaps the bitstream signal can/will also be recognized by an older processor as simply Dolby True, and would in turn play as such. Otherwise an older processor like the XMC-1 would basically be useless for Atmos encoded discs. That’s basically all I’m looking for it to do, Dolby True and DTS Master, but via analog, not HDMI.

When it comes down to it, the bottom line I’m looking for is the answer to this: Should / can an old Blu-ray player decode the 5.1 / 7.1 Dolby True “out” of a disc with only Atmos encoded on it, and then send it to a processor via 7.1 analog (or even HDMI PCM)? Could it depend on the player? The firmware? Both? I would think any player with decoding firmware would be similar to a processor with decoding firmware. If an older processor can interpolate the 7.1 Dolby True out of an Atmos bitstream signal, why couldn’t an older player do the same?

Anyone know?

Thanks for any help in advance.

Cheers ----- Bonzo

[cawgijoe]

Strange.

I have a two year old Oppo 103 and have noticed no issues with newer bluray discs that also carry an Atmos track. I have kept up with my firmware updates. I do use HDMI. My XMC-1 of course does not do Atmos.

[KeithL]

The answer is YES; an Atmos disc is supposed to be fully backwards compatible with TrueHD.

Here's a quote from the Dolby Labs Atmos white paper "Dolby Atmos for the Home Theater":
"Dolby Atmos audio tracks (both Dolby TrueHD and Dolby Digital Plus) are backward compatible. If you play a movie mixed in Dolby Atmos on a non Dolby Atmos system, you’ll experience traditional 5.1 or 7.1 audio, depending on the configuration of your speaker system. This means content providers don’t need to provide separate Dolby Atmos and non Dolby Atmos mixes. One mix supports both"

HOWEVER, note that, just as the producer of the disc controls what you hear when you play the Atmos mix, they also control what you get when you play the non-Atmos mix. For example, they might decide to provide an Atmos mix and a 5.1 channel regular mix, or a different version of the regular mix than they provide on the non-Atmos disc. There's no specific requirement that, for a given disc, the 7.1 channel mix you hear on a non-Atmos system will be the SAME as the version you would hear on a 7.1 channel Atmos-decoded system - although it's certainly possible. 

(And, yes, Red Box has been known to create custom versions of discs that don't include all of the audio formats that were present on the original.)

If your player is set to "bit stream" the current version of the XMC-1 will decode an Atmos disc as TrueHd (the appropriate "fall back format").
If your player is set to do the decoding itself, it will be sending analog to the XMC-1, so no additional decoding will be possible.
(You can't do any "Atmos decoding" once your content has been converted to analog.)
It is my understanding that ANY player or processor that can decode TrueHD will play an Atmos disc as TrueHD.

Jan 30, 2017 12:26:29 GMT -5 Bonzo said:

So we rented The Secret Life of Pets Blu-ray from RedBox last night and it’s what I believe to be the first disc we’ve gotten with Atmos on it. When we played the movie, I noticed almost immediately that there was very little, if any, sound coming from the surround speakers. I got up and put my ear next to the right side surround speaker. There was indeed sound, but it was very faint, not at all what should be coming out. And it appeared as that while I was getting at least some sound from the side surrounds, there was nothing in back. So I was getting very quiet 5.1, not 7.1. It also appeared that there wasn’t much truly deep LFE signal in the movie, something I find hard to believe. I checked the POP menu on the disc and the only English option was Atmos. I checked the speaker levels in the Blu-ray player and all was accurate. So I started thinking about what could be wrong.

[NOTE: I need to mention right now that since my old Denon receiver does not have HDMI, I currently use the Panny Blu-ray player to do the Dolby True / DTS Master surround decoding, and it sends those signals via 7.1 analog to my Denon, where I use the 7.1 analog inputs, and the Denon applies ZERO processing to the signal, except overall volume control.]

With this in mind, my first thought was that perhaps my Blu-ray player needed a firmware update. As it turns out, there was a new update put out in 2015. I didn’t have time to check my player yet, but I think I may be missing this update. I’m almost positive the firmware version I currently have is from the upgrade before, which was in 2012. But regardless, I’m thinking that this 2015 upgrade isn’t really going to matter for this particular issue, because anything done in 2015 was before Atmos discs even existed. I’m going to look into it further tonight, but I really don’t think it will fix this issue.

My second thought was, I wondered if this was an issue with the Red Box release of this disc? RedBox has been known to skimp on extras etc so I was wondering if they put on a “limited” Atmos only version on this disc. Is this even possible?

It was my understanding until last night that Atmos and DTS:X are supposedly fully backwards compatible formats. They were made this way so people with older processors and players could still enjoy their Dolby True and DTS Master without having to immediately upgrade just to hear what they had before. But in reading stuff last night and this morning, I can’t find much talking about my 7.1 analog situation. What I did find is that it appears there aren’t many people worried about being able to play Atmos discs to get 5.1 / 7.1 Dolby True, either via analog or HDMI. What there are is people worried that their old player won’t send the Atmos signal to their new processors so they actually get Atmos. (The logic being that “of course” a new processor is required for Atmos, but the question being do you also need a new player?). And the fix for that is, using HDMI, set the player to bitstream (not PCM), and then the new processor will play the full Atmos signal. Basically, the older player will send 100% of the unprocessed Atmos signal via bitstream using some technique that new processors will understand and “expand” it to full blown Atmos. I’m thinking that using the same sort of thought process, that perhaps the bitstream signal can/will also be recognized by an older processor as simply Dolby True, and would in turn play as such. Otherwise an older processor like the XMC-1 would basically be useless for Atmos encoded discs. That’s basically all I’m looking for it to do, Dolby True and DTS Master, but via analog, not HDMI.

When it comes down to it, the bottom line I’m looking for is the answer to this: Should / can an old Blu-ray player decode the 5.1 / 7.1 Dolby True “out” of a disc with only Atmos encoded on it, and then send it to a processor via 7.1 analog (or even HDMI PCM)? Could it depend on the player? The firmware? Both? I would think any player with decoding firmware would be similar to a processor with decoding firmware. If an older processor can interpolate the 7.1 Dolby True out of an Atmos bitstream signal, why couldn’t an older player do the same?

Anyone know?

Thanks for any help in advance.

Cheers ----- Bonzo

[ngmitter]

Jan 30, 2017 12:26:29 GMT -5 Bonzo said:

When it comes down to it, the bottom line I’m looking for is the answer to this: Should / can an old Blu-ray player decode the 5.1 / 7.1 Dolby True “out” of a disc with only Atmos encoded on it, and then send it to a processor via 7.1 analog (or even HDMI PCM)? Could it depend on the player? The firmware? Both? I would think any player with decoding firmware would be similar to a processor with decoding firmware. If an older processor can interpolate the 7.1 Dolby True out of an Atmos bitstream signal, why couldn’t an older player do the same?
Cheers ----- Bonzo

Bonzo,

Unfortunately, you absolutely need a BITSTREAMED signal from the blu-ray player to the receiver, which is currently only achievable by HDMI.

It is correct that a TrueHD or DTS-MA signal can be sent over analog, but the player converts the bitstreamed codec from the blu-ray into LPCM. It is still bit perfect, but uncompressed at this point. In this sense, bitsream is like a "zip file" with the blu-ray player doing the "unzipping". If you ran HDMI via bitstream to the receiver, then the receiver "unzips" the audio stream.

So now that we have a basic understanding of the bitstreamed codecs, we need to look at how Atmos works. Atmos takes uncompressed master audio (the TrueHD track), but also has positional data. Rather than be constrained by being assigned to 5.1 or 7.1 channels, there are many more audio tracks (32 or 64 maybe?). When you send analog audio from your blu-ray player to your receiver, there is no positional data sent in the audio signal. This is why you can only achieve Atmos (or DTS:X) from an HDMI signal that also carries positional data.

To expand on this, you basically would need a blu-ray player that can do Atmos processing internally, which likely would never happen. Atmos relies heavily on the position of the speakers in your environment to properly allocate the audio to each speaker.

EDIT: After re-reading your post, I think I missed the mark a bit. Atmos and DTS:X encoded is add information hidden in the TrueHD and DTS:MA codec. If the disc supports Atmos or DTS:X, then it definitely supports normal TrueHD or DTS:MA, which the blu-ray play can then decode to LPCM over analog.

In regards to your Redbox comment, I'm worried that most Redbox releases will not have Atmos in them. Most I get don't even have the DTS:MA or TrueHD tracks. This is a known omission from Lionsgate films. It's likely done intentionally.

[Bonzo]

Jan 30, 2017 14:19:40 GMT -5 KeithL said:

It is my understanding that ANY player or processor that can decode TrueHD will play an Atmos disc as TrueHD.

Well, then in theory it should have played just fine. Hmmmmmmmmmmm?

I've been racking my brain this morning and I THINK we may have in fact rented another movie that was Atmos encoded. I can't remember what it was, but I vaguely remember kidding my wife saying something like "just wait until I upgrade so we sound coming out of the ceiling!" What ever it was, it played just fine.

So at this very second, today, I'm leaning towards the RedBox disc.

[Bonzo]

Jan 30, 2017 14:46:28 GMT -5 ngmitter said:

EDIT: After re-reading your post, I think I missed the mark a bit. Atmos and DTS:X encoded is add information hidden in the TrueHD and DTS:MA codec. If the disc supports Atmos or DTS:X, then it definitely supports normal TrueHD or DTS:MA, which the blu-ray play can then decode to LPCM over analog.

You're hitting the mark now. Yep, my Panny Blu-ray player (DMP-BD80) fully decodes Dolby True and DTS Master, and has 7.1 channel distance / level adjustments built in. We have been watching regular Blu-rays for years now with no issues.

In regards to your Redbox comment, I'm worried that most Redbox releases will not have Atmos in them. Most I get don't even have the DTS:MA or TrueHD tracks. This is a known omission from Lionsgate films. It's likely done intentionally.

Funny (and interesting) that this one seems to have the exact opposite problem. Says Atmos, but won't do Dolby True properly. At least on my player last night.

What I need to do now is check all the Blu-rays I've bought in the last 6 months or so to see if any have Atmos on them. If so, then I can do some testing to see what I get and go from there.

Thanks ngmitter and KeithL for your input. Helps me think at least I'm not totally crazy.

[hosko]

It would be difficult to alter the fallback codec ATMOS, its not like True HD fallback to DD which is a separate file (which I always remove when I rip discs)

[Gary Cook]

Does it have a selection on the The Secret Life of Pets Blu-ray menu? Like "audio" and then a drop down menu for what codec? All of the Atmos BD's (albeit not many) that I have seen have had that choice.


Cheers
Gary

[Bonzo]

Jan 30, 2017 20:21:31 GMT -5 Gary Cook said:

Does it have a selection on the The Secret Life of Pets Blu-ray menu? Like "audio" and then a drop down menu for what codec? All of the Atmos BD's (albeit not many) that I have seen have had that choice.


Cheers
Gary

Yes, but it's the only "english" choice. So I'm sure its also the default.

[Bonzo]

I was able to determine / do a few things last night.

My wife confirmed that it was in fact a "Red Box" altered disc. There was a screen with pictures for tons of "extra bonus features," but none of them were accessible on the disc. My wife said the disc literally said something to the effect of "to view these extras, please purchase the Blu-ray from you favorite retail outlet."

Also, I was able upgrade the firmware on my player. Some people I read about on a forum had troubles, and so did I at first. The instructions say to use the CD burning software that comes with your computer. But all I got was a coaster. The player said "E-DISC," or error disc as I translated it. The instructions stressed that the copy had to be only ISO9660 (what ever that means), so I redid it using my Nero software choosing ISO9660 as the option, and it it worked. So I should be good there, I just need to test it now.

More to follow.........

[goozoo]

Couple of things. If you have a newer player with analog out (like an OPPO) problem solved and no need to decode it after the signal leaves the player. This much has been explained already. As for the disc, that movie was not recorded very well audio wise and pretty much relied on the front three channels. You might want to try another ATMOS disc like Jack Reacher Never Go Back for better audio. The ATMOS discs are still hit or miss at this point. That being said, if you do find a good disc you will know right away.

[Bonzo]

Feb 1, 2017 1:13:39 GMT -5 goozoo said:

Couple of things. If you have a newer player with analog out (like an OPPO) problem solved and no need to decode it after the signal leaves the player. This much has been explained already. As for the disc, that movie was not recorded very well audio wise and pretty much relied on the front three channels. You might want to try another ATMOS disc like Jack Reacher Never Go Back for better audio. The ATMOS discs are still hit or miss at this point. That being said, if you do find a good disc you will know right away.

Wow, so you are saying the movie itself was that way? So DVD with 5.1 DD or Blu-ray with Atmos (Dolby True), either one basically sucks in terms of surround sound effects? Because that's exactly what it was; all front 3 channels, with little to nothing in the rear, and not much (if any) low LFE. What in the heck were they thinking? Regular bland TV shows have more oomph. Very disappointing.

I will certainly be investigating this more on my system when time allows. Perhaps this weekend maybe. I'll get back here to report. Unfortunately I probably won't ever get the chance to review this particular movie again, because quite frankly, while it had it's moments, it just wasn't that great.

[Bonzo]

goozoo, well, I found this article that clearly backs up exactly what you are saying. Most of the online reviews I found are for the UHD-Bluray, and it seems like all of them actually used Atmos (not just 5.1 or 7.1 Dolby True). But they even describe the Atmos overhead effects as being limited and not totally immersive. This article below actually calls out the quiet "wall" speaker channels, which is, with Dolby True, all I had. But that fact that a movie such as this wasn't chalk full of surround sound effects still surprises the heck out of me. In today's age of surround, this movie gets very low marks from me. This is the type of movie that "should" have over blown surround. Very disappointing.

I hope this isn't some sort of early disc trend to try and hype Atmos height speakers. "Show off the heights and turn down the sides so the heights stick out more" kind of thing. Or worse yet, sound guys worried so much about the new height channels that they leave the "wall" surrounds behind. Kind of like when 3D movies started up again a few years ago, the first movies had totally stupid scenes just to showcase and over indulge 3D. That would be a big "el sucko" if more movies come out like this.

www.forbes.com/sites/johnarcher/2016/12/05/the-secret-life-of-pets-ultra-hd-blu-ray-review/#1e8e067e768b

It’s not a showcase audio mix by any means, but the only actual disappointment comes from its use of the rear channels. They seem too quiet in the mix and are mostly reserved for general atmospheric effects (such as an under water ‘gurgle’ during the van sinking sequence) rather than throwing in lots of the positional detailing and back to front/front to back transitions the best Dolby Atmos mixes routinely deploy.