Atmos: who can provide the simplest explanation? - AVS Forum
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post #1 of 14 Old 06-27-2014, 12:26 PM - Thread Starter
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Atmos: who can provide the simplest explanation?

I'll try:

Dolby Atmos has "audio beds" and "objects".
Audio beds are channels, just like the ones in 2.0, 5.1, 7.1 etc configurations.
Objects are sounds that are independent from channels. There can be up to 128 objects simultaneously.

Now let's assume that a soundtrack is composed of a stereo acoustic guitar, and a mosquito flying around in a room.

The acoustic guitar will be mixed as "audio bed". This means that it will be heard through the front left and front right speakers, no matter how many speakers the system is composed of.

The mosquito flyes across the room. As it moves, it will be heard from the speaker(s) that are closest to the position of the mosquito in the room. If the mosquito flies in every corner of the room, it will be heard in turn from every speaker. If there are 2, it will be heard from 2. If there are 9, it will be heard from 9. If there are 64, it will be heard from 64 speakers. So, one single object can be heard from up to 64 different speakers.

Now the mosquito exits the room, and 128 bees enter the room, but they fly close, and they stay near a corner. Each bee has been recorded separately, and each bee is an audio object. As they stay in the same place, they will be heard from just one or two speakers. So, 128 different objects can be heard from just one or two speakers. Should they spread across the room, they will be heard from all the speakers.

Does any of this make sense to you? Audio beds are just channels. They are the static part of Atmos. The audio bed part will go to fixed speakers, no matter where they are.

Audio objects will go to those speakers that the Atmos decoder deems as the closest to where the audio object should be.

That is why even if you don't have ceiling or height speakers, even if you have a 3.1 system, you will benefit from Atmos. The audio objects will be, in every case, be reproduced by the best speaker.

(This post is intended just as an idea to help all those AVS members who seem to be struggling with these new concepts. I hope someone will write something a lot better that what I did. English is obviously not my native language! )

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post #2 of 14 Old 06-27-2014, 12:38 PM
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I admit I have yet to be sold on anything beyond 7.1.

My explanation would be that it's yet another surround sound technology few will care about in the near future. Seen them come and go. I suppose for a dedicate home theater setup in a home, it might add something. I hear it's used in some theaters and some movies, which makes sense - they have the money and space to setup a lot of speakers unlike most homes.

There's a lot of choices besides Atmos, such as Yamaha numerous presence channel modes. Until I experience a mind-changing demo, I am not going to be pre-impressed by the concept of overhead speakers - not sure it matters enough with how humans hear. Heck, even surround sound is not a mind blowing change IMO. I like it and all, but two quality speakers, sufficient power and a good subwoofer setup is pretty great. 5.1 is probably a sufficient upgrade that most people would not care about 7.1.

As for your processing question, I don't know. There's probably some very sophisticated algorithms involved that few people have seen the source code for. I would think a lot of the details are proprietary. Wikipedia has some basic info. You can read how there can be a lot of channels being mixed down to a smaller subset of speakers. I can appreciate curiosity on the specifics, but without a decent white paper on the topic, I can't imagine too many people know the details.

This seems to be the main feature, from wikipedia - "During playback, each theater's Atmos system mixes and renders all dynamic sounds in real-time to make it seem each sound is coming from its designated spot, in a manner customized to that particular theater's speaker configuration." In other words, the sound is downmixed in a way that's specific to the theater where it's being played back. I don't see how that's going to work as well at home, without detailed measurements or a very sophisticated room correction system.
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post #3 of 14 Old 06-27-2014, 01:31 PM
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It would be really nice to get some specs on both the cinema and home versions of Atmos, since AVR's are already being sold that will reportedly support it by the end of the year (via. firmware update).

Cinema version
The cinema version is a hybrid of fixed channel audio for 9.1 discrete channels, called the "channel bed", and object-based audio, which is rendered on the fly, and can use any/all of the available speaker channels.
Can support up to 64 discrete channels and 128 objects.
Supposedly treats dialogue as an object, which allows you to adjust the volume of the dialogue without adjusting the volume of the rest of the audio coming from the center channel.
Any other key features?

Home version
The home version is a hybrid of fixed channel audio for up to 7.1 (9.1 is in the works) discrete channels, called the "channel bed", and object-based audio, which is rendered on the fly, and can use any/all of the available speaker channels.
Current Atmos-enabled AVR's coming out from Onkyo & Pioneer appear to support as few as 8 discrete channels and as many as 12 discrete channels in the following configurations: 5.1.2, 5.1.4, 7.1.2, 7.1.4, and 9.1.2.
Marantz will be releasing their new flagship pre-pro, the 8802, either late 2014 or early 2015. It supports up to 13.1 discrete channels and will reportedly support Dolby Atmos. Theoretically, this would allow you to use the following set ups: 5.1.8, 7.1.6, 9.1.4, or 11.1.2. I assume that 9.1.4 would be the recommended setup when using a 13.1 channel receiver for Atmos.
The Atmos soundtracks on Blu-Ray support up to 34 discrete channels, with up to 24 on the floor (arrayed around the front, back, and sides of the room) and 10 overhead.
What is the maximum number of objects supported by Dolby Atmos soundtracks on Blu-Ray?
Supposedly treats dialogue as an object, which allows you to adjust the volume of the dialogue without adjusting the volume of the rest of the audio coming from the center channel.
Any other key features?

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post #4 of 14 Old 06-27-2014, 01:38 PM
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Quote:
Originally Posted by antoniobiz1 View Post
. . . (This post is intended just as an idea to help all those AVS members who seem to be struggling with these new concepts. I hope someone will write something a lot better that what I did. English is obviously not my native language! )
You make perfect sense to me. I saw everything you said. Thank you.
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post #5 of 14 Old 06-27-2014, 01:47 PM
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The OP is actually a good and succinct description of the differences between channels and objects - thank you.

Theatrical Atmos white paper: http://www.dolby.com/uploadedFiles/A...for-Cinema.pdf

The channel bed for the cinema implementation is 9.1 (same as the 7.1 we all know and love, but with 5 channels behind the screen instead of 3).

All 64 speakers (or up to 64, I should say) can be used for the object rendering. The beds are played back out of only those speakers assigned to the beds.

For the home theater implementation, details are still unknown. It appears that the bed is 7.1, and the maximum current channel count is 12 (7.1.4 or 9.1.2) with all 11 speakers being used for the object rendering.

As to the dialogue-as-object concept - certainly that could be done, but I've not seen any hardware (on either the theatrical or home theater side) that indicated that it would have functionality for the user to independently adjust volume on a single object. Has anyone else seen such a thing?
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post #6 of 14 Old 06-27-2014, 02:35 PM
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Quote:
Originally Posted by dschulz View Post
Theatrical Atmos white paper: http://www.dolby.com/uploadedFiles/A...for-Cinema.pdf

The channel bed for the cinema implementation is 9.1 (same as the 7.1 we all know and love, but with 5 channels behind the screen instead of 3).
The white paper you linked to says: "These beds can be created in different channel-based configurations, such as 5.1, 7.1, or even future formats such as 9.1 (including arrays of overhead loudspeakers)."



Lts/Rts = Left Top Surround and Right Top Surround?
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post #7 of 14 Old 06-27-2014, 02:38 PM
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GREAT EXPLAINING. Makes sense to me thanks.
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post #8 of 14 Old 06-27-2014, 02:50 PM
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Quote:
Originally Posted by sdurani View Post
The white paper you linked to says: "These beds can be created in different channel-based configurations, such as 5.1, 7.1, or even future formats such as 9.1 (including arrays of overhead loudspeakers)."



Lts/Rts = Left Top Surround and Right Top Surround?
Good catch! And a reasonable guess on Lts/Rts, though I don't know for sure.
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post #9 of 14 Old 06-27-2014, 02:53 PM
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Quote:
Originally Posted by MichaelJHuman View Post
I admit I have yet to be sold on anything beyond 7.1.

My explanation would be that it's yet another surround sound technology few will care about in the near future. Seen them come and go. I suppose for a dedicate home theater setup in a home, it might add something. I hear it's used in some theaters and some movies, which makes sense - they have the money and space to setup a lot of speakers unlike most homes.

There's a lot of choices besides Atmos, such as Yamaha numerous presence channel modes. Until I experience a mind-changing demo, I am not going to be pre-impressed by the concept of overhead speakers - not sure it matters enough with how humans hear. Heck, even surround sound is not a mind blowing change IMO. I like it and all, but two quality speakers, sufficient power and a good subwoofer setup is pretty great. 5.1 is probably a sufficient upgrade that most people would not care about 7.1.

I agree 100%.

There's nothing to see here.

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post #10 of 14 Old 06-27-2014, 03:00 PM - Thread Starter
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Quote:
Originally Posted by MichaelJHuman View Post
I admit I have yet to be sold on anything beyond 7.1.

My explanation would be that it's yet another surround sound technology few will care about in the near future. Seen them come and go. I suppose for a dedicate home theater setup in a home, it might add something. I hear it's used in some theaters and some movies, which makes sense - they have the money and space to setup a lot of speakers unlike most homes.

There's a lot of choices besides Atmos, such as Yamaha numerous presence channel modes. Until I experience a mind-changing demo, I am not going to be pre-impressed by the concept of overhead speakers - not sure it matters enough with how humans hear. Heck, even surround sound is not a mind blowing change IMO. I like it and all, but two quality speakers, sufficient power and a good subwoofer setup is pretty great. 5.1 is probably a sufficient upgrade that most people would not care about 7.1.
Quote:
Originally Posted by unavol View Post
I agree 100%.
Thank you both for your replies, but this is not an Atmos appreciation thread. It is a place to come up with an explanation of its inner workings easy enough to be understood by everybody.
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post #11 of 14 Old 06-27-2014, 05:46 PM
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Agreed, I should probably have withheld my editorial

"But this one goes up to 11"
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post #12 of 14 Old 06-27-2014, 06:03 PM
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Here is a FAQ.

http://blog.dolby.com/2014/06/dolby-...ions-answered/

And this site has speaker layouts.

http://www.digitaltrends.com/home-th...-theaters/#/10

Has anyone seen the Onkyo video?


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post #13 of 14 Old 07-12-2014, 11:14 AM
 
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post #14 of 14 Old 07-12-2014, 11:50 AM
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There isn't any really firm information. This all came to be in the middle of a speaker upgrade. In talking with a number of experts, I'm going to do a 7.5 bed of sound and front heights that are identical to LCRs (for high output), side heights, and rear heights. All 6 heights will be angled down to main listening position. All height speakers will be angles down at approx 30 a 45 degrees. Essentially, it's an Auro 3- D set up that I hope will work with Armos... I hope..

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