# Atmos track explained, 7.1 vs 5.1.2



## gvsk

I have the new onkyo nr 646 that is atmos ready and dts x compatible. 

I have a traditional 7.1 set up currently. With klipsch reference premiere 280f,450c, 240S's as surrounds and 160m as back surrounds. 
All my surrounds are not at ear level but at height at roof line pointing down. 

I don't have a flat roof line so gave up on the gimic of even trying atmos enabled speakers. 

Until dts x gets completely dominant I have to settle for Dolby atmos tracks. 

I am not able to get a complete explanation of how the atmos track on the bluray works. My reicever links the surround backs and heights so for 7.1 they are surround backs and for 5.1.2 I get the atmos effects from the rear surrounds which doesn't make sense. 

I basically have to change the wiring when watching atmos movies so as to get atmos height effects from the middle surrounds and the rear surrounds take place of the middle surrounds. 

Now coming to atmos track what's the difference other than the height effects is in the original track, ie playing atmos on a 7.1 setup is the same as playing Dolby true HD on a 7.1 system?

What is the best way for me to enjoy these movies. Leave it at traditional 7.1 atmos or try and get what ever little atmos effects I can from the center surrounds(5.1.2). If I set it up 

Every atmos bluray has the audio track explained as 7.1 atmos (American sniper , Jupiter ascending) is it an error or are they trying to mean Dolby 7.1true HD + atmos. 

I was of the the opinion that atmos is object based audio but is it mainly based on a base Dolby true HD track but just adding height effects. Or every object is designed to come out of the speakers based on their Lay out and not designated channels 

I might be all over the place here but want to see what the best way to experience atmos movies is with my current 7.1 set up ie using my middle surrounds as height channels. Or is it even worth it because I won't get any effects since the speakers aren't directly over head??

Help me out to the best of your abilities.


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## bkeeler10

Atmos for home consists of 7 "bed" channels (which is the same as the standard 7.1 we are used to), plus audio "objects." Sounds can be encoded to the "bed" channels as before, or they can be encoded as objects - not assigned to a particular channel but rather to a location in space. A sound that is encoded in a bed channel will always play from that channel. An object, however, will be steered by the Atmos decoder, or renderer (which knows the speaker layout and positioning), to the appropriate speaker or set of speakers to make it sound the way it was intended.

The way an Atmos soundtrack works on blu ray is as follows: First of all, the whole thing is encoded using the TrueHD scheme, just as a non-Atmos track is. The difference is that an Atmos track has the objects encoded as metadata. When you play an Atmos soundtrack using a standard 5.1 or 7.1 system, the objects are folded into the "bed" channels so you hear them but not with the same precision or in exactly the same way as intended. But if you play the Atmos soundtrack on an Atmos receiver configured for an Atmos layout, the receiver will decode the "bed" channels and the object metadata and steer it all to where it needs to go, within the context of your particular speaker layout.

Regarding your receiver using the same speaker outputs for back surrounds and heights: I am not familiar with that receiver, but most likely what happens is you tell it in some setup menu whether you have "heights" connected or back surrounds connected. 

If you tell it you have heights, you will be able to play Atmos soundtracks on a true Atmos system. Non-atmos soundtracks will play 5.1 (unless you engage DSU (Dolby Surround Upmixer), in which case you will get matrixed sound to your heights).

If you tell the receiver you have back surrounds connected, you will not have a true Atmos system. Rather, it will be a standard 7.1 system. Your receiver will not decode the Atmos objects, but rather just the standard 7.1 channel mix will play with the objects embedded in the channel(s) as well as can be done.

It would be very impractical to attempt to run 5.1.2 for Atmos tracks and 7.1 for non-Atmos tracks. You would have to switch the configuration in the receiver and then move the speakers from the height position to the surround back position. Or you could have speakers in the surround back position and the height position and switch wires on the back of the receiver.

The better thing to do is to configure the system as 5.1.2. Atmos tracks will play as intended. Then, for non-Atmos tracks, engage the DSU (Dolby Surround Upmixer, found on all Atmos-enabled receivers). Or get a 9 channel unit that can run 7.1.2.

Long explanation, but only a short introduction to Atmos.

Edit: If you want to set up a 5.1.2 system, the "height" channels (really, overhead channels) must be properly placed. For a 5.1.2 system, that postion will be on the ceiling, about in line with the front left and right speakers (or slightly closer together), and somewhere between slightly forward of or slightly behind the listening position. If you can't do that, I wouldn't bother trying to set it up as 5.1.2 - just set it up as standard 7.1 and enjoy!


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## gvsk

So unless I have a 7.1.2 or 7.1.4 or 5.1.2 or 5.1.4 system the atmos objects will not be transcoded by the reicever even if I have an atmos enabled receiver playing in 7.1 setup?

So I won't get atmos effects unless I tell the receiver that I have height speakers.


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## bkeeler10

The way it works, if I understand correctly, is that on an Atmos bluray, the objects are embedded into the bed channels. If a non-Atmos receiver (or an Atmos receiver set up as a standard 7.1 receiver) plays the track, the objects are played through the bed channels in some way. But, if the receiver is Atmos capable, there's a scheme to remove the objects from the bed channels and instead route them via the Atmos decoder to the speakers that are most appropriate.

What I'm saying is that you will not lose the sounds that are objects if you play an Atmos track on a non-Atmos receiver. But I'm also saying if you play an Atmos track on a non-Atmos receiver, and then play it again on an Atmos receiver _not set up as such_, the two will decode exactly the same.


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## Talley

I wonder how I could even think about doing atmos in my room. You can see my space above my head is a slanted ceiling... I wouldn't have any issues running wire or mounting speakers... I'd surface mount them and run the wiring in pvc along the ceiling (i'm an electrician and i'm going for function... NOT looks).

However the first reflection points on my ceiling are right at the spot above my head the point where the speakers in a 5.2.2 system would want the heights. 

I think for me atmos is a no go. Which is why I don't care about it.


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## bkeeler10

Talley said:


> I wonder how I could even think about doing atmos in my room. You can see my space above my head is a slanted ceiling... I wouldn't have any issues running wire or mounting speakers... I'd surface mount them and run the wiring in pvc along the ceiling (i'm an electrician and i'm going for function... NOT looks).
> 
> However the first reflection points on my ceiling are right at the spot above my head the point where the speakers in a 5.2.2 system would want the heights.
> 
> I think for me atmos is a no go. Which is why I don't care about it.


Well the range of angles for the top speakers are somewhat flexible. Take a look at the diagram attached and note that the speakers you'd use in a 5.2.2 system would be designated "top middle." So it can be installed at an angle from 65 degrees to 100 degrees elevation.


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## Talley

i dunno... all these speakers just causes more issues with room interaction.

I think I'll stick to a 5.2 system


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## gdstupak

gvsk said:


> My reicever links the surround backs and heights so for 7.1 they are surround backs and for 5.1.2 I get the atmos effects from the rear surrounds which doesn't make sense.
> I basically have to change the wiring when watching atmos movies so as to get atmos height effects from the middle surrounds and the *rear surrounds take place of the middle surrounds*.


With Atmos 5.1.2 the L/R Surround speakers should be in the same location as in a basic 5.1configuration, they should be beside you, not behind you as Back Surround speakers (some call these Rear Surrounds) would be located. 
So if you are wanting Atmos 5.1.2 you would use the Surround speakers (that are beside you) and the Atmos Height channels/speakers would be directly above your head. 



gvsk said:


> Now coming to atmos track what's the difference other than the height effects is in the original track, ie playing atmos on a 7.1 setup is the same as playing Dolby true HD on a 7.1 system?
> So unless I have a 7.1.2 or 7.1.4 or 5.1.2 or 5.1.4 system the atmos objects will not be transcoded by the reicever even if I have an atmos enabled receiver playing in 7.1 setup?
> So I won't get atmos effects unless I tell the receiver that I have height speakers.


An Atmos encoded soundtrack (5.1.2 or 7.1.4) doesn't add more surround audio than a standard surround encoded soundtrack (5.1 or 7.1). The Atmos encode just moves sound differently. 
As an example think of a sound effect such as rain. Both formats, Atmos & standard, will contain the sound of rain. The Atmos encode might have more of the sound of rain in the Height speakers with some also in the Surrounds. The standard encode will have the same sound of rain, but it will all play in the Surrounds (because there are no Heights). 




gvsk said:


> What is the best way for me to enjoy these movies. Leave it at traditional 7.1 atmos or try and get what ever little atmos effects I can from the center surrounds(5.1.2).
> ...but want to see what the best way to experience atmos movies is with my current 7.1 set up ie using my middle surrounds as height channels. Or is it even worth it because I won't get any effects since the speakers aren't directly over head??


I have no experience with these new height encoded formats so I am speculating here...

#1...Without Height speakers correctly placed directly overhead, I would not tell the AVR that I have Atmos Height speakers. 
#2...I would not use the L/R Surround speakers (you call them middle surrounds) as Atmos Heights. As L/R Surround channels, they are probably already getting the same audio that would be sent to a dedicated Atmos Height channel. But if you use your L/R Surround speakers as Atmos channels, you may actually be getting less audio through them than if you used them as L/R Surround channels. As an example... using the speakers as Surrounds, it may have the sound of rain falling on the roof and a loud door slamming beside you... using the same speakers as Atmos Heights, it may have the sound of rain but not the sound of the door slamming.
#3...I've read that the standard 7.1 configuration is more satisfying than an Atmos 5.1.2 configuration. Stepping up to the Atmos 7.1.2 or 7.1.4 is supposedly worthwhile.

With your current speaker configuration, I would leave it as standard 7.1.


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## Docrog

I have asked the following question on several different on-line forums, so I might as well try it here. Please note that x.2.x indicates front and rear subwoofers.

I currently have a speaker layout configured as 5.2.4. Using the same speakers, I previously identified it as 7.2.2. I merely changed the setting in the Yamaha RX-A3000 to regard the rears as in-ceiling presence speakers, instead of rear surrounds.

I am planning on purchasing the Yamaha RX-A3050 (Dolby Atmos and DTS:X capable) when it is released later this month. My current AVR up-mixes legacy 5.1 & 7.1 sound tracks to 5.2.4 via their proprietary Cinema DSP 3D algorithm. 

Although it seems possible (but costly) for me to add yet another pair of rear speakers to achieve a true 7.2.4 layout, my question is whether or not there is sufficient information contained in the up-mixed legacy 5.1 sound tracks (by, for example, the Dolby DSU) to justify the project. I am aware that, if I stay with my current 5.2.4 designation, rear channel cues in a 7.1 encoded Blu-Ray movie will be redistributed to my side surrounds (and, possibly, the rear presence speakers). 

Does anyone have opinions related to the degree of superiority between 7.2.4 versus 5.2.4 in the HT? Thanks!


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## gdstupak

Docrog said:


> I currently have a speaker layout configured as 5.2.4. Using the same speakers, I previously identified it as 7.2.2. _I merely changed the setting in the Yamaha RX-A3000 to regard the rears as in-ceiling presence speakers, instead of rear surrounds_.


Are your back/rear speakers located at a lower height that is typical of surround rears, or are they at ceiling height?


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## willis7469

gdstupak said:


> Are your back/rear speakers located at a lower height that is typical of surround rears, or are they at ceiling height?


 sorry Glenn, I'll have to quote you since I can't find his quote that you quoted(whew). I think if he left them in a "normal" rear surround position, as you're asking him, would not be very successful. (Agreeing with you if that's where you're going here). Even at ceiling height.


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## Docrog

Glenn, when the room serving as my HT was originally constructed in 2006, both my side and rear surrounds were placed in-ceiling. These in-ceiling side surrounds are radiating dipoles and the rear "surround" speakers are directional. As I previously wrote, I've now "re-assigned" the in-ceiling rear speakers as "presence" rather than "surround" within the set-up of the Yamaha RX-A3000. The Cinema DSP 3D program in this AVR seems to be doing a superior job in providing a more convincing soundfield on legacy 5.1 movies with this current 5.2.4 setting compared with the original 7.2.2 setting. The soon to be released RX-A3050 will allow me to identify them as "overhead". 

It's possible (although not easy) for me to mount either wired or (preferably) battery operated wireless rear "surround" speakers on the back wall (but well above ear level because of "wife acceptance factor") for a 7.2.4 layout, but I'm trying to determine whether or not there's a significant advantage gained in the soundfield of a 7.2.4 layout versus a 5.2.4 layout in my room before I go through the expense and effort needed to add that extra pair. Although native 7.1 Blu-Ray discs do contain some amount of rear surround information/cues, the question (for me) remains whether the DSU/DSP algorithms in the new AVRs make sufficient use of rear surrounds in their up-mix of native 5.1 encoded discs to 7.2.4 to actually be noticeable.

FYI, the front "presence" speakers are mounted on-wall at approximately 7 feet; they are located higher, wider and closer to my main listening position than my front speakers (tweeters near ear level). They are/will be identified as "height" rather than "overhead".


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## gvsk

Again coming back to the original topic. 
I have read conflicting views on this so I am going to ask this again

Every where is says atmos delivers sound based on object in 3d space so Not channel based so should sound different than a 7.1dthd track which are purely channel based. 

Default speaker set up 7.1

Scenarios

Atmos track played in an atmos enabled reciever (capable of 5.1.2 , onkyo nr646) with above speaker setup , will is sound the same as Dolby true HD 7.1 track. 

It's hard for me to believe that adding two atmos ceiling or height speakers will change the way the sound is delivered from channel based to 3d atmos object based.


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## chris0228

As I understand it, from a content standpoint, you're not going to hear anything that was mixed specifically for those ceiling speakers. You will, however, get a more immersive experience by having sound come down at you from those speakers than you would from your side and rear surrounds ideally placed just above ear level. The content, for example sake let's say a helicopter comes from behind you directly over the top to the center of the screen, the metadata will be processed in a way using delay to simulate additional steps if you will, from back to front to give the audio illusion that the sound of the helicopter is coming from above you. 

Again, nothing specifically mixed to those outputs, but of the demos I have heard, it's very much an improvement of the full immersive sound experience than a 7.1 system.


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## bkeeler10

gvsk said:


> Again coming back to the original topic.
> I have read conflicting views on this so I am going to ask this again
> 
> Every where is says atmos delivers sound based on object in 3d space so Not channel based so should sound different than a 7.1dthd track which are purely channel based.
> 
> Default speaker set up 7.1
> 
> Scenarios
> 
> Atmos track played in an atmos enabled reciever (capable of 5.1.2 , onkyo nr646) with above speaker setup , will is sound the same as Dolby true HD 7.1 track.


As far as I have been able to tell in all my reading on the subject, an Atmos capable receiver, set up for and running a standard channel-based 7.1 system, will produce the same result as a 7.1 receiver without Atmos processing would produce.



> It's hard for me to believe that adding two atmos ceiling or height speakers will change the way the sound is delivered from channel based to 3d atmos object based.


But that is exactly how it works. Once you tell the receiver you have an Atmos layout, the objects will be unpacked and decoded from the metadata, and steered to the most appropriate speakers as your setup allows.

Perhaps the confusion comes because you expect the Atmos layout to be purely object-based? It isn't really. The Atmos system for home consists of seven channels (which work the same way 7.1 always has) plus an object-based "layer," if you will. In an Atmos mix, there will be sounds assigned to channels and sounds that are objects. The sounds assigned to channels will only play from those channels regardless of your speaker count and configuration. The sounds that are objects can play from any speaker or set of speakers, depending on your layout and as the Atmos renderer sees fit, to most accurately position those sounds based on where they were placed spatially in the mix.


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## bkeeler10

chris0228 said:


> As I understand it, from a content standpoint, you're not going to hear anything that was mixed specifically for those ceiling speakers. You will, however, get a more immersive experience by having sound come down at you from those speakers than you would from your side and rear surrounds ideally placed just above ear level. The content, for example sake let's say a helicopter comes from behind you directly over the top to the center of the screen, the metadata will be processed in a way using delay to simulate additional steps if you will, from back to front to give the audio illusion that the sound of the helicopter is coming from above you.
> 
> Again, nothing specifically mixed to those outputs, but of the demos I have heard, it's very much an improvement of the full immersive sound experience than a 7.1 system.


That is basically correct. The only speakers in an Atmos layout that have content specifically for them are the 7 "bed" channels (which comprise the typical 7.1 standard layout). The rest of the speakers (overheads and wides) do not have content specifically for them - what they play is determined by the Atmos renderer in the receiver.

Taking your helicopter example, flying from behind to overhead to the center of the screen. If that helicopter sound is encoded as an object, it will traverse the speakers necessary to place that sound the way it was placed spatially in the mix. It may start in the back surrounds and slowly pan from them to the overheads speakers and possibly side surrounds, and then pan from those speakers to the center and perhaps left and right speakers. If you have a 7.1.4 system, the way it is rendered (that is, which speaker gets which sound at a particular time) will be different than if it is played on a 5.1.2 system. It is intuitive that the 7.1.4 layout will lend itself to smoother panning and a more realistic sound field than the 5.1.2 layout.


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## Peter Loeser

bkeeler10 said:


> As far as I have been able to tell in all my reading on the subject, an Atmos capable receiver, set up for and running a standard channel-based 7.1 system, will produce the same result as a 7.1 receiver without Atmos processing would produce.
> 
> 
> 
> But that is exactly how it works. Once you tell the receiver you have an Atmos layout, the objects will be unpacked and decoded from the metadata, and steered to the most appropriate speakers as your setup allows.
> 
> Perhaps the confusion comes because you expect the Atmos layout to be purely object-based? It isn't really. The Atmos system for home consists of seven channels (which work the same way 7.1 always has) plus an object-based "layer," if you will. In an Atmos mix, there will be sounds assigned to channels and sounds that are objects. The sounds assigned to channels will only play from those channels regardless of your speaker count and configuration. The sounds that are objects can play from any speaker or set of speakers, depending on your layout and as the Atmos renderer sees fit, to most accurately position those sounds based on where they were placed spatially in the mix.


Great explanation.


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## Blacklightning

My question is, do you need to follow the 7.1 placement rules for Atmos or can your just place speakers where ever you want or in a circle around the seats.


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## bkeeler10

Blacklightning said:


> My question is, do you need to follow the 7.1 placement rules for Atmos or can your just place speakers where ever you want or in a circle around the seats.


The standard 7.1 speakers should be placed according to the same guidelines they always have been placed. The exception is that they recommend that those channels all be placed around ear level. Some adaption will be necessary to avoid the side listeners in a row casting acoustic shadows from the surrounds for the middle people in the same row. IIRC Dolby recommends that the surrounds be no more than 1.25 times the seated ear height. If you have a 7.1.x layout, another way to avoid shadowing for the side surrounds is to place them a little forward of the seating position (say 80-85 degrees instead of 90 degrees).

All the guidelines can be found by following this link.


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## gvsk

This is what Dolby labs told me. It is opposite what everyone talking about here


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## willis7469

gvsk said:


> This is what Dolby labs told me. It is opposite what everyone talking about here


 What I think he means is the atmos content will get sent to the regular surrounds(side and rear surrounds). IIRC, I saw an explanation saying atmos tracks played back on a non atmos system contain all of the same "sounds", but the atmos decoder sends the object sounds to overhead speakers, or in the case of a "regular" setup the object sounds just get mixed into the "core" track.


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## Peter Loeser

gvsk said:


> This is what Dolby labs told me. It is opposite what everyone talking about here


What they're saying is an Atmos AVR will render the objects to however many channels you have. So your 7.1 system gets the 7.1 bed channels from the Doby TrueHD track just as it always would, and then the renderer scales the objects based on your whole system. It doesn't matter if there are zero overheard speakers or ten overhead speakers. The statements I've seen here support Dolby's response.

edit: Just to add some clarity. Atmos can render the objects in 2D or 3D. If you have a 7.1 system, they will be rendered in 2D. If you have 7.1.x they will be rendered in 3D.


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## willis7469

Peter Loeser said:


> What they're saying is an Atmos AVR will render the objects to however many channels you have. So your 7.1 system gets the 7.1 bed channels from the Doby TrueHD track just as it always would, and then the renderer scales the objects based on your whole system. It doesn't matter if there are zero overheard speakers or ten overhead speakers. The statements I've seen here support Dolby's response.


 That's why it's important to tell the receiver which layout you have correctly.


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## Peter Loeser

willis7469 said:


> That's why it's important to tell the receiver which layout you have correctly.


Absolutely. And taking the time to do a proper calibration can make a big difference.


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## gvsk

Thanks for the expert advice


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## gvsk

But with objects added in 2d space in the 7.1 set up which are absent in true HD track how can both thee tracks sound the same ?


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## asere

I have the same avr. My set up has always been 5.1 mains floor standing and surrounds in ceiling. 
I also have two height in ceiling.
Last night I used 5.1.2 for Atmos. It felt just like 7.1 set up.
Sorry don't mean to hijack this thread. Just wanted to share since I have same avr.

Sent from my SM-G900P using Tapatalk


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## gdstupak

@gvsk
There is no audio subtracted or added between these formats, it's just that the audio is presented differently depending on the speaker layout.
The 3d speaker layout will move some of the audio from the side/rear surround speakers and place them into the overhead atmos speakers.


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## bkeeler10

So my understanding is that an Atmos soundtrack is composed of the standard bed channels (just like a regular 7.1 mix) plus object metadata. All the object sounds are embedded in the standard 7.1 mix as well as in the object metadata. So if a standard 7.1 receiver (or an Atmos receiver set up with a standard 7.1 layout) plays the track, no sounds are lost. It plays the 7.1 track, completely ignorant of the object metadata stream but playing all those sounds anyway because they are embedded in the channel based mix. If an Atmos renderer plays the track, there is a scheme (the details of which I am not familiar with) that removes the object sound from the 7.1 layout. Then the Atmos renderer decodes the object metadata and steers it where it should go.

So there is no conflict between what we've been saying and what Dolby told you. All the sounds will play on a 7.1 system, but they will be strictly channel-based. And that's how the Atmos track is backwards-compatible with legacy decoders.

As I understand it, FWIW.


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## Peter Loeser

bkeeler10 said:


> So my understanding is that an Atmos soundtrack is composed of the standard bed channels (just like a regular 7.1 mix) plus object metadata. All the object sounds are embedded in the standard 7.1 mix as well as in the object metadata. So if a standard 7.1 receiver (or an Atmos receiver set up with a standard 7.1 layout) plays the track, no sounds are lost. It plays the 7.1 track, completely ignorant of the object metadata stream but playing all those sounds anyway because they are embedded in the channel based mix. If an Atmos renderer plays the track, there is a scheme (the details of which I am not familiar with) that removes the object sound from the 7.1 layout. Then the Atmos renderer decodes the object metadata and steers it where it should go.
> 
> So there is no conflict between what we've been saying and what Dolby told you. All the sounds will play on a 7.1 system, but they will be strictly channel-based. And that's how the Atmos track is backwards-compatible with legacy decoders.
> 
> As I understand it, FWIW.


Once again, good explanation. 100% of the Atmos soundtrack is contained within 7.1 channels of the TrueHD track. The metadata simply tells the Atmos renderer which objects to extract and place in 3D space, unconstrained by the 7.1 bed channel configuration. SO... if it is played back on only 7.1 channels, nothing is lost.

Now, in the case of the OP, playing an Atmos soundtrack with an Atmos AVR in a 7.1 speaker configuration, I think the AVR is still using the metadata to place the objects beyond the discrete 7.1 channels. In which case a 7.1 only system would still theoretically benefit from an Atmos AVR when playing back Atmos tracks, since it could still place objects with precision in 2 dimensions. I hadn't considered this case before now.


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## bkeeler10

Peter Loeser said:


> Once again, good explanation. 100% of the Atmos soundtrack is contained within 7.1 channels of the TrueHD track. The metadata simply tells the Atmos renderer which objects to extract and place in 3D space, unconstrained by the 7.1 bed channel configuration. SO... if it is played back on only 7.1 channels, nothing is lost.


I'm going to be picking nits here. The end result is what we are most interested in, and the end result is as you say. But I think we're saying slightly different things about the process to get there. 

An Atmos track contains two parts: The bed channels and object metadata. In order to be fully backward-compatible with legacy 7.1 decoders, all the sounds of the object metadata are embedded in the bed channels as well. So there are two copies of the object sounds -- one embedded in the 7.1 channels and the other as object metadata.

Only the Atmos decoder knows what to do with object metadata; the legacy TrueHD decoder either doesn't see that data or does not know what to do with it. Either way, it is discarded. So the legacy TrueHD decoder takes an Atmos track and plays only the bed channels because that's all it knows how to do. But since the object sounds are encoded into the 7.1 channels, no sound is omitted.

The Atmos decoder plays the 7.1 channels and also plays the object metadata. This would result in the objects being played twice: once in the 7.1 channels and again as steered by the Atmos decoder. Obviously no good. So there is an algorithm in the Atmos decoder to strip the embedded object sounds from the 7.1 channels. That way, it is only played once and it is played in the most accurate way possible.



> Now, in the case of the OP, playing an Atmos soundtrack with an Atmos AVR in a 7.1 speaker configuration, I think the AVR is still using the metadata to place the objects beyond the discrete 7.1 channels. In which case a 7.1 only system would still theoretically benefit from an Atmos AVR when playing back Atmos tracks, since it could still place objects with precision in 2 dimensions. I hadn't considered this case before now.


I don't think that is the case. If the Atmos AVR is set up with a 7.1 system, the Atmos decoder does not come into play. In that case, it acts the same as a non-Atmos AVR.

Sorry to be so picky about the details. I will stress that this is how I understand it based on what someone said in a thread over at AVS several months ago. As I recall, he delved into the patents Dolby has on this stuff and this is how he explained it. In the end it doesn't matter as long as the end result is correct.

We now return you to your regularly scheduled programming.


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## Blacklightning

Saw this awhile back, hope it answers some questions.


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## Peter Loeser

I look at TrueHD as a package that contains the audio data and "instructions" for the decoder. The metadata does not contain audio, but rather cues that tell the decoder what to do with the audio. Dolby used metadata in its surround formats before Atmos, but its function has evolved over time and the introduction of Atmos has turned it into a buzzword.



bkeeler10 said:


> Only the Atmos decoder knows what to do with object metadata; the legacy TrueHD decoder either doesn't see that data or does not know what to do with it. Either way, it is discarded. So the legacy TrueHD decoder takes an Atmos track and plays only the bed channels because that's all it knows how to do. But since the object sounds are encoded into the 7.1 channels, no sound is omitted.
> 
> The Atmos decoder plays the 7.1 channels and also plays the object metadata. This would result in the objects being played twice: once in the 7.1 channels and again as steered by the Atmos decoder. Obviously no good. So there is an algorithm in the Atmos decoder to strip the embedded object sounds from the 7.1 channels. That way, it is only played once and it is played in the most accurate way possible.


If the Atmos decoder can locate and strip the objects out of the bed channels and ignore them, then why couldn't it extract them and render them in 3D with the metadata? i.e. why have two copies of the objects? I don't think I would consider the method described to be lossless playback.




bkeeler10 said:


> I don't think that is the case. If the Atmos AVR is set up with a 7.1 system, the Atmos decoder does not come into play. In that case, it acts the same as a non-Atmos AVR.


If playback can be scaled to any configuration and the AVR can decode the Atmos mix, then why not do it in this case? I guess if the AVR disables all Atmos features when you don't have overhead speakers connected, then it would revert to traditional TrueHD decoding no matter what.

Our living room setup uses an AVR that happens to be Atmos capable, but with only a 3-channel passive soundbar and a sub. I use DSU for playback in most cases, but haven't actually tried an Atmos disc. Might have to experiment tonight if I can commandeer the remote for a bit.


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## bkeeler10

Peter Loeser said:


> I look at TrueHD as a package that contains the audio data and "instructions" for the decoder. The metadata does not contain audio, but rather cues that tell the decoder what to do with the audio. Dolby used metadata in its surround formats before Atmos, but its function has evolved over time and the introduction of Atmos has turned it into a buzzword.
> 
> If the Atmos decoder can locate and strip the objects out of the bed channels and ignore them, then why couldn't it extract them and render them in 3D with the metadata? i.e. why have two copies of the objects? I don't think I would consider the method described to be lossless playback.


You may well be right about this. Perhaps the metadata for Atmos objects is just instructions and not actual audio. 



> If playback can be scaled to any configuration and the AVR can decode the Atmos mix, then why not do it in this case? I guess if the AVR disables all Atmos features when you don't have overhead speakers connected, then it would revert to traditional TrueHD decoding no matter what.


I think that's how it works. I think you have to have it configured for overheads (or wides) before the Atmos renderer becomes active. But there seems to be some debate about this and I could be totally wrong of course. 



> Our living room setup uses an AVR that happens to be Atmos capable, but with only a 3-channel passive soundbar and a sub. I use DSU for playback in most cases, but haven't actually tried an Atmos disc. Might have to experiment tonight if I can commandeer the remote for a bit.


So it would be interesting to see if, when playing an Atmos track, the AVR display distinguishes between traditional TrueHD (if it is configured with no object "channels") and Atmos (if object channels are present).


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## gdstupak

Some interesting info from the video....

- (time 24:45-27:00) 'Metadata' is the data that an Atmos decoder uses to steer object based audio to certain locations. If no Atmos decoder is available, then all of the audio (both object based and channel based) will still play but it will all be treated as channel based audio. All audio is located together in the bitstream, the metadata is a separate info pack located in the bitstream (if there is no Atmos decoder, then the metadata info pack is ignored).

- (time 27:00) Atmos is enabled with any speaker configuration above 5.1. So a 7.1 speaker configuration (no height speakers) will still enable the Atmos based object audio.

- (time 28:08) While running a home theater 7.1 speaker configuration, an Atmos disc *can *sound better than a standard 7.1 soundtrack (the Dolby guy actually says "_*will actually*_ sound better," but I believe it would be inaccurate to word it that way). According to the Dolby guy, pre-Atmos commercial theater sound systems did not allow for full range audio content into the surround speakers, but now Atmos commercial theater sound systems do allow for full range surround content. So with Atmos, the movie audio mixer isn't "afraid" to put more "full" sound into the surround speakers.


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## bkeeler10

gdstupak said:


> Some interesting info from the video....
> 
> - (time 24:45-27:00) 'Metadata' is the data that an Atmos decoder uses to steer object based audio to certain locations. If no Atmos decoder is available, then all of the audio (both object based and channel based) will still play but it will all be treated as channel based audio. All audio is located together in the bitstream, the metadata is a separate info pack located in the bitstream (if there is no Atmos decoder, then the metadata info pack is ignored).
> 
> - (time 27:00) Atmos is enabled with any speaker configuration above 5.1. So a 7.1 speaker configuration (no height speakers) will still enable the Atmos based object audio.
> 
> - (time 28:08) While running a home theater 7.1 speaker configuration, an Atmos disc *can *sound better than a standard 7.1 soundtrack (the Dolby guy actually says "_*will actually*_ sound better," but I believe it would be inaccurate to word it that way). According to the Dolby guy, pre-Atmos commercial theater sound systems did not allow for full range audio content into the surround speakers, but now Atmos commercial theater sound systems do allow for full range surround content. So with Atmos, the movie audio mixer isn't "afraid" to put more "full" sound into the surround speakers.


:doh: :doh:

Well, thanks for rewatching it and picking that information out. I did watch this video right when it was published, but that was almost a year ago. That bit about Atmos being enabled on any configuration above 5.1 does sound familiar, now that you mention it. So it seems that the Atmos decoder does come into play on a 7.1 layout and that theoretically the reproduction of audio objects from an Atmos soundtrack on an Atmos AVR running a 7.1 system could be better/more accurate (or at least different) than a non-Atmos AVR running the same setup and track.

Shows you what I know. I apologize for the blatant spreading of misinformation . . . <tail between legs>


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## gvsk

Finally what I want to hear from the experts.


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## Peter Loeser

I did try an Atmos disc on my 3.1 setup last night. Configured as 3.1, it handled it as a traditional TrueHD track. I changed the config in the settings to 7.1 and tried again and it enabled the Atmos decoder as mentioned in the video. Unfortunately I couldn't tell you if it sounded better than standard TrueHD since I didn't actually hook other speakers up. Though now I'm tempted to run wiring for 5.1.2 in my living room. Thanks a lot guys!


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## willis7469

Mmmwahahaha!!!!!!


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## gdstupak

Peter Loeser said:


> ... Unfortunately I couldn't tell you if it sounded better than standard TrueHD since I didn't actually hook other speakers up. Though now I'm tempted to run wiring for 5.1.2 in my living room. Thanks a lot guys!


If listening with a conventional 2D 7.1 speaker configuration, I don't know what Atmos would add to the experience. The soundtrack, whether Atmos enabled or not, is already directing audio to specific side/back surround speakers. The Atmos metadata has no reason to redirect any audio (no height speakers to redirect audio to).

If listening with a new 3D speaker configuration, the Atmos metadata has a reason to redirect audio differently (take audio out of a side surround speaker and play it in a height speaker).


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## asere

I notice that with 5.1.2 there is not a lot of sound going to the heights. I was told it could be the way they are mixed and varies from movies. I tried 3 so far and not much Atmos content with heights.

Sent from my SM-G900P using Tapatalk


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## Peter Loeser

asere said:


> I notice that with 5.1.2 there is not a lot of sound going to the heights. I was told it could be the way they are mixed and varies from movies. I tried 3 so far and not much Atmos content with heights.
> 
> Sent from my SM-G900P using Tapatalk


It will vary from one movie to the next, and is certainly determined by the original mix. I haven't found any of the Atmos Blu-rays I've watched so far to make overwhelming use of the overhead speakers. Are you referring to playback of Atmos-enabled soundtracks or using the Dolby Surround Upmixer with non-Atmos content?


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## asere

Peter Loeser said:


> It will vary from one movie to the next, and is certainly determined by the original mix. I haven't found any of the Atmos Blu-rays I've watched so far to make overwhelming use of the overhead speakers. Are you referring to playback of Atmos-enabled soundtracks or using the Dolby Surround Upmixer with non-Atmos content?


I'm referring to Atmos enabled soundtrack.


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## Peter Loeser

asere said:


> I'm referring to Atmos enabled soundtrack.


Keep in mind, the purpose of the object-based audio formats is not to put a bunch of extra sounds in the overhead channels, but to make the best use of a 3-dimensional speaker array to pinpoint the location of those objects within the space.


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## asere

Peter Loeser said:


> Keep in mind, the purpose of the object-based audio formats is not to put a bunch of extra sounds in the overhead channels, but to make the best use of a 3-dimensional speaker array to pinpoint the location of those objects within the space.


I see. That explains why you can easily tell the overhead speakers are more active with Dolby upmixing vs Atmos track.


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## Blacklightning

asere said:


> I see. That explains why you can easily tell the overhead speakers are more active with Dolby upmixing vs Atmos track.


Same with the back channel for 7.1 (at least for Starwars). When I play the 7.1 track the side channel is on all the time playing music and ambient noise while the back channel is only used when needed 2-5% of the time. But if you upmix it's on as much as the side channel.


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## Peter Loeser

Blacklightning said:


> Same with the back channel for 7.1 (at least for Starwars). When I play the 7.1 track the side channel is on all the time playing music and ambient noise while the back channel is only used when needed 2-5% of the time. But if you upmix it's on as much as the side channel.


That's because PLII and DTS Neo create matrixed back channels using information from the side channels of a 5.1 mix. DSU works a little differently (I'm honestly not sure of the details) but it's still pulling information from the discrete channels like PLII and DTS Neo do. In other words, if the back channels of a 7.1 soundtrack or the height dimension of an Atmos soundtrack were not emphasized in the original mix, then using an upmixer will likely result in more perceived content coming from the extra speakers.


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## willis7469

Blacklightning said:


> Same with the back channel for 7.1 (at least for Starwars). When I play the 7.1 track the side channel is on all the time playing music and ambient noise while the back channel is only used when needed 2-5% of the time. But if you upmix it's on as much as the side channel.


 that's how it seems in my system too.(7.3.0 lol) For reasons I can't explain yet, the two ATMOS movies I have, sound different in their representation than I would expect from a regular track. Better channel separation, cleaner delivery etc. In my head? Not sure, but I like it.
+Peter


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## asere

I made an observation between Atmos and TrueHD. I noticed that when on Atmos the bass and dynamics was more intense than TrueHD. 
Some have told me it is all the same between Atmos and TrueHd as far as bass and dynamics goes. Is this correct? And if that is the case that it's the same how come I noticed the big difference?


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## JBrax

asere said:


> I made an observation between Atmos and TrueHD. I noticed that when on Atmos the bass and dynamics was more intense then TrueHD. Some have told me it is all the same between Atmos and TrueHd as far as bass and dynamics goes. Is this correct? And if that is the case that is the same how come I noticed the big difference?


 There is most certainly a difference. I've noticed that most Atmos tracks are much hotter in regards to LFE. Sometimes to the point that I've got to come down a notch or two in the settings.


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## bkeeler10

That is an interesting observation. I would not have thought it would be that way, and can't think of a technical explanation of why LFE would be stronger when decoding Atmos. Hmm...


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## JBrax

bkeeler10 said:


> That is an interesting observation. I would not have thought it would be that way, and can't think of a technical explanation of why LFE would be stronger when decoding Atmos. Hmm...


 I'm not sure why either? I watched Independence Day last night with a DTS:X track and that wasn't the case. I've always found DolbyTrueHD tracks to be hotter than DTS. Why? Not sure but that's been my experience.


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## asere

JBrax said:


> There is most certainly a difference. I've noticed that most Atmos tracks are much hotter in regards to LFE. Sometimes to the point that I've got to come down a notch or two in the settings.


Thank you! I know I wasn't hearing things. I even had my wife listen and she agreed. 
Now is the processor a factor in that or does any Atmos capable receiver do this?


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## JBrax

asere said:


> Thank you! I know I wasn't hearing things. I even had my wife listen and she agreed. Now is the processor a factor in that or does any Atmos capable receiver do this?


 I would say it's all about the Atmos mix.


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## asere

Guys my apologies. I know this is not the right thread to post this but I have a question on banana plugs. 
I currently have the ones on this link that you have to unscrew and kink the tip of the cable to hold in place but they slide out at times.
Which ones do you recommend other than the one here?
https://www.amazon.com/Cable-Matter...2939&sr=1-2-spons&keywords=banana+plugs&psc=1


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