Originally Posted by cannga
Andy that *is* an Atmos diagram. Atmos does not have overhead "channel" in the strict "definitive" sense of the word channel, but it does have height speakers that produce the equivalent "channel" using object oriented surround.
Atmos is a simultaneous introduction of 2 separate aspects of surround sound technology, that are somewhat un-related to each other:
1. Object oriented surround (vs. channel based surround)
2. Height information using
3. Additional height speakers
You actually don't need 1 to have 2: you could process height information without object oriented surround technology (this is what Auro does). It just so happens Dolby decides to introduce 1 and 2 together as a package.
The way I look at it: you don't even need 3 to have 2 as evidenced by the overhead flies in my system due to elevation of my surround speakers, it's just that 3 will make the sound hyper-real :-) and that's what we are after. I believe those ceiling speakers work by the same reason/logic that the center speaker works:
A. "anchors" sound in a specific location (the middle in the case of center speaker) for people sitting to the side, and
B. increases clarity/solidity/realism of center image for everyone, both those sitting to the side, and those sitting in the center.
Again, pure speculation based on what I've learned - any expert pls correct as needed.
The way Atmos was explained to me, was by those who had not only experience, but creating it as well. What i was told was very tech heavy and most, but not all, went in one ear and out the other ear. From what i understand, is that Dolby Atmos is a matrix that is added during post production sound mixing that "creates" a overhead channel that item specific elements, Helicopter, jet, bullet, etc is induced to this channel to give a true surround sound effect that is higher than the height speakers can duplicate. And large explosions and other "360" sounds are also sent to the over heads as part of the Atmos logic matrix. I was also told the need for multiple over head speakers "softened" the effect and that you could basically have one giant overhead speaker.
Auro was explained to me as having added a second and up to a third layer of speakers producing a 3D sound effect, and uses the standard 5.1 PCM stream. This was also explained to me as having the same speakers at there normal height, then adding a "second" set of speakers higher up directly over the lower speakers, and if the end user so chooses a "third" set of over head downward firing speakers could be added to make what is termed "voice of God" channel. Then the decoder, decodes the 5.1 PCM stream of the Auro 3D mix and fires what speaker gets that sound, based on the number of speakers the system is working with, as this has to be manually entered.
What i do know, is that Atmos is more rendering on the audio processor and not so much sound mixing in post production, Auro is more adjustment at the sound mixing during post development and less rendering by the audio processor. So in effect they are two completely different systems to deliver 3D sound.
During the mastering session, the stems, objects, and metadata are brought together in a Dolby Atmos package that is signed off in the dubbing theater and is carried through to exhibition in the cinema.
The RMU can render the necessary "channel" based mixes..
If you want to read the rest this it is on page 10 of the official Atmos white paper. And if Dolby is calling the overheads "channels" then so will I.
Once page has loaded click on Dolby Atmos Next-Generation Audio for Cinema.