[opus] Antw: Re: Antw: [EXT] Opus merging streams

Ulrich Windl Ulrich.Windl at rz.uni-regensburg.de
Wed Apr 6 07:54:44 UTC 2022

>>> Sampo Syreeni <decoy at iki.fi> schrieb am 06.04.2022 um 08:36 in Nachricht
<alpine.DEB.2.21.2204060925220.47345 at lakka.kapsi.fi>:
> On 2022‑04‑06, Ulrich Windl wrote:
>> Incidentially I came across a Dolby Atmos demo that had about 118 
>> channels wirh 24bit audio at 48kHz, all in one huge WAV file 
>> yesterday.
> Is that even a legitimate encoding?! What the fuck.
>> When I tried to play that (in plain stereo) with audiacity, even my 
>> fast computer (i7 at 4GHz) had dropouts. So I can imagine that 
>> decoding a large number of channels and mixing those seems to be a bad 
>> idea.
> It is. Which is why my favourite ambisonics exists (sales pitch): it's a 
> principled and nigh entropically speaking optimum way to fold down a 
> static central soundfield down to a number of channels. Third order, so 
> sixteen channels, seems to be upto the task for *any* central isotropic 
> soundfield at all, and the system yields to static optimization.
> I cannot for the life of me understand why Atmos exists. Except for 

I don't know the theory behind, but I guess they want a format open to future
sound designs (i.e.: how many and where to place speakers).
Similar why DCPs (Digital Cinema Packages) encode color in CIE XYZ (you can
encode invisible "colors").
I guess the idea also was not to restrict the color space to the limits of any
existing device.
Or maybe they just want to fight pirated copies by filling up the disks faster

> patent patent law or something like that. If it was used to express a 
> live gaming or augmented reality setup, with arbitrary auditory 
> parallax, I could get the point. But that's not what Atmos or even Dolby 
> AC‑4 are about. They just encode a static scene ‑‑ in a way *much* more 
> complicated and heavier on the processor than a "simple" third degree 
> periphonic ambisonic HOA signal set would be, and in a manner not 
> amenable to low resource optimizations in surround sound. The object 
> based encoding simply seems stupid and superfluous.

Maybe computer games, military or science needs such; I really don't know...
"tinning reality", maybe


> ‑‑ 
> Sampo Syreeni, aka decoy ‑ decoy at iki.fi, http://decoy.iki.fi/front 
> +358‑40‑3751464, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2

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