Question Height channels from a 7.1 source.

geosiv

Member
Hi all,

Assuming I have built some kind of a setup that consists, among others, of 2 ceiling speakers, such as 5.1.2, or 7.1.2. If my source is a typical 7.1 one (it consists of L, R, C, LFE, Ls, Rs, Lb, and Rb channels) am I going to have my ceiling speakers driven with anything?

I'm not talking about pseudo-effects, such as Dolby Atmos Height Virtualization Technology, I'm just trying to understand this:

If the audio part of a file is labelled as a "Dolby TrueHD with Dolby Atmos" for example, and it also says it has 11 Dynamic Objects, but it still is an 8-channel one, is there any other info inside it that will make the (Dolby Atmos capable) amplifier to direct some of the sound to the ceiling speakers? Or do I always need source files with as much channels as my total channels of my audio setup?

Many thanks in advance,

George
 

Damp Squid

Active Member
If the source is 5.1 or 7.1 and you do not use the up-mixer, either Dolby Surround or DTS Neural X, then there will be no sound from the ceiling speakers.
It's the metadata attached to the Dolby True HD track which tells the receiver where to place the objects in which ever height speakers you are using . The receiver will map the sound to however many speakers you have, you have to give it this information when setting it up.
 

gibbsy

Moderator
Dolby Atmos is metadata contained within a Dolby TrueHD audio stream. To enable decoding of Atmos metadata a receiver will need to be correctly configured and have a minimum speaker set up of 5.1.2 with the .2 being the Atmos domain. This can be either speakers in or on the ceiling, upfiring modules placed on the front left and right front speakers or two speakers high on the front wall and angled towards the MLP. Same applies to DTS:X.

You will find Atmos on blu ray or UHD discs and they will labelled as 'Dolby Atmos'. With streaming services many use the Dolby Digital Plus platform which can carry the Atmos metadata. These include (in the UK) Netflix, Amazon Prime and Disney, amongst others.

The upmixing modes of Dolby Surround and DTS Neural will upmix non Atmos material to use those ceiling speakers and both are effective Neural especially.

If you have a look at the link below it will show you how those speakers should be arranged in the ideal room. Almost all receivers on the market today with the exception of entry level models include the ability to decode Atmos.

 

geosiv

Member
Thank you both for your replies, they are really much appreciated.

You made me read more through them, so please let me make a statement and tell me if I get it right:

Let's say that I have a super-quality 4K BluRay, which is mastered with everything that Atmos can offer.

  • If I rip this disc (let's say uncompressed) to an mkv file and play this file through a USB stick on my TV's USB input, I'll get its audio in 2-channel.
  • If I play the BluRay disc through a BluRay player and use my TV for audio reproducing, I'll get the same results as above.
  • If I play the BluRay disc through a BluRay player but feed its audio output to a simple 5.1 amplifier, I'll just get 5.1 surround sound.
  • If I play the BluRay disc through a BluRay player but feed its audio output to a super amplifier (let's say a Denon AVC-X8500H which is a 13.2 channel one), but only have a 5.1 speaker setup in my living room, I'll get just 5.1 surround sound, as above.
  • If I play the BluRay disc through a BluRay player but feed its audio output to a super amplifier (let's say a Denon AVC-X8500H which is a 13.2 channel one), but have a 7.1.6 or 9.1.4 speaker setup (as Denon says), then I'll have all available audio objects offered to me.
What I'm trying to say with the above, is that: "If the audio part of a disc is mastered with Dolby TrueHD, the information is (always) there (and has nothing to do with how many channels the audio has inside it) - it is only depending to your audio setup (amplifier and number of speakers) in order to have the full details uncovered. If, for example, I have 2 speakers on my ceiling, I'll hear (almost every) top audio from them, but if I have 4 speakers on my ceiling, I'll hear the front top sounds from the front ones, while the rear top ones from the rear ones.

Did I get it right?
 

Sloppy Bob

Distinguished Member
Did I get it right?
Nearly, but not quite.

If you have the super AVR and use the upscaling on it. You can use all the channels, even if it's only a 5.1 track.
It will give you an Atmos effect and steer audio into the extra channels. I don't know how it works exactly other than it's witchcraft and it can work outstandingly well.

If you don't use the upscaling, it will just give you exactly what's on the disc. If you have a 21.2.6 system it will just give you 5.1

If you have 6 speakers on the ceiling vs 2 speakers then it's not the same audio coming through all the speakers at the same time.

With the 2 speakers you'd hear, with a Tie-Fighter for example in Star Wars, it flying above you left to right.
If you had 6 it could move diagonally from the front left speaker, to the middle right speaker and then to the rear left (and back, and around and quieter to seem further away and louder to feel closer) to give an effect of it buzzing around you.
 
Last edited:

geosiv

Member
Sloppy Bob, thank you too, for your reply.

As I was writing an even longer "last" question, you guys made me search a little bit better this time and I realized the error in my initial statement: If I have a 7.1 Atmos track with 11 Dynamic Objects, it means I actually have an 11-channel + 1 LFE track, which is the typical/more used mix of home theater BluRay's. To say it better, the who-knows-how-many dynamic objects of the movie as it is experienced in the theater, were all sent to these 12 channels during the preparation of the audio track for home theater use and if you have such a setup in your house, you are almost guaranteed that you're going to hear almost everything from most of your movies.

Once again, thank you all for your comments and help.
 

gibbsy

Moderator
Your terminology is wrong. 7.1 is a base set up with all speakers at or just above a seated head height. If you have speakers in the Atmos domain then you expand on that 7.1 set up to 7.1.4, the .4 being the speakers in the Atmos domain. The Denon AVC X8500 is capable of portraying 7.1.6 or 9.1.4. The X8500 is Denon's top tier amp.

Most close to top of the range amps will have an 11 channel ability giving a substantial 7.1.4. The amp will decode the Atmos metadata and place those objects in the correct speakers for movement across and around the soundstage when called for in the soundtrack.

Do not expect the ceiling to suddenly come alive with sounds when you play an Atmos title, it is more subtle than that and many people get disappointed the first time they listen to Atmos in their own home. Even in nature there are not many sounds that come from above, humans are poor at sounds that are higher than around 30°. Just stand outside and listen to the sounds around you.

When those object based sounds are required, something like a helicopter flying over, then Atmos is very good at portraying it and directors will often have ambient sounds in the Atmos domain. One of the best movies to put you in the middle of an all enveloping soundstage is Everest when the storm hits. That is Atmos at it's very best.
 

geosiv

Member
Yes, you are correct, but I was referring to the properties of the audio file being a 7.1 one (which I guess is correct). Whether a 7.1 audio track is a "simple" track containing no dynamic objects or is a "full" Atmos one containing info for all 11 objects (plus the 12th one, the LFE), is something that has to do only with the track itself. As a matter of fact, this was the reason for starting this thread: I realized through MediaInfo that all Atmos tracks I have are 8-channel ones - I was expecting to see more channels in its properties such as "Top front left", "Top front right" etc. It was then, after Damp Squid's answer that I realized that the info for all "channels" are included in the audio track and they are driven to whichever speakers you have in your setup, be it your tv's 2 speakers, or your 5.1 ones, or your 7.1 ones (no height effects till now), or the x.x.2, x.x.4, x.x.6, or x.x.8.

Anyway, all your answers helped me dig deeper, and as I said I have read that most home-theater discs are mastered with 7.1.4 setups in mind, so if you build such a system, you are good to go for some time. Denon's AVR-X3600H seems to be the cheapest one that supports this amount of discreet speakers.

Cheers,

George
 

gibbsy

Moderator
Huge difference in the audio quality of the Denon X3600 and the X8500. The very least I would go for is a X4500. I have a X6500. All models above the X3600 has the very good AL32 processor onboard and that can make a big difference in soundstage steering.
 

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