What happens to the height channels in atmos with legacy true hd?

Y

yepimonfire

Audioholic Samurai
With a 7.1 true hd stream, the dolby digital core obviously has the rears folded into the surrounds, if you down mix 5.1 or 7.1 into plain 2.0 pcm (without dolby surround encoding), all channels are folded into the fronts, but with the appropriate phase angles. Run a stereo down mix of a 5.1 track through Dolby Pro logic II and 90% of the original surround track is restored with startling accuracy in my experience. In current 5.1 and 7.1 mixes, sounds originating from overhead, such as an airplane takeoff or helicopter, have the sound with the appropriate phase angles for overhead sound amorphously mixed into the surrounds, since a proper setup places the surround slightly above the listener, the sort of has the illusion of being overhead. Run this through Pro logic IIz and the sound actually does come from overhead now.

I'm curious if a similar scenario will happen with atmos. Will the height channels be blended into the surrounds and then be able to be approximately extracted via PLIIz. I'm guess it won't simply because the height channels aren't really channels at all, but objects placed into a 3 dimensional sound space.

Thoughts?

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William Lemmerhirt

William Lemmerhirt

Audioholic Overlord
Maybe? An atmos decoder will see the flagged metadata "objects" and place them accordingly, but the pro logic decoder will still work the same as always and if it extrapolates those sounds it will probably just be as intentional as luck. I've never tried my system in pliiz but plIIx has been marginally successful IME.


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j_garcia

j_garcia

Audioholic Jedi
It plays back as TrueHD and gets redirected to the other speakers. It will not "approximate" but I do notice Atmos and DTS-X tracks sound more "spacious" even in 5.1 playback.
 
BlwnAway

BlwnAway

Audioholic
With a 7.1 true hd stream, the dolby digital core obviously has the rears folded into the surrounds, if you down mix 5.1 or 7.1 into plain 2.0 pcm (without dolby surround encoding), all channels are folded into the fronts, but with the appropriate phase angles. Run a stereo down mix of a 5.1 track through Dolby Pro logic II and 90% of the original surround track is restored with startling accuracy in my experience. In current 5.1 and 7.1 mixes, sounds originating from overhead, such as an airplane takeoff or helicopter, have the sound with the appropriate phase angles for overhead sound amorphously mixed into the surrounds, since a proper setup places the surround slightly above the listener, the sort of has the illusion of being overhead. Run this through Pro logic IIz and the sound actually does come from overhead now.

I'm curious if a similar scenario will happen with atmos. Will the height channels be blended into the surrounds and then be able to be approximately extracted via PLIIz. I'm guess it won't simply because the height channels aren't really channels at all, but objects placed into a 3 dimensional sound space.

Thoughts?

Sent from my SM-G360T1 using Tapatalk
Basically correct, a PLIIz AVR will only play what's in the channels, not metadata no matter what, but.....
This is why there are special 5.1 & 7.1 mixes on Atmos discs, this way the sound mixer can decide to add those overhead sounds into the channels instead of making them objects.
It's all up to the mixer.
 
Bob Leonard

Bob Leonard

Junior Audioholic
My system is setup to auto detect Dolby EX, and DTS ES 7.1. When playing a Dolby Atmos encoded Blu-ray, my system a Lexicon MC-12 will play this new audio format as Dolby EX.
 

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