Le 2018-07-29 à 05:56 PM, Stefan Schreiber a écrit :
1. I believe that the opus encoders/decoders have always supported
more than 8 channels.
Correct, but when encoding 8 or less channels, correlation is applied in
ways that are incompatible with Ambisonics; for example, the LFE channel
is filtered... With more than 8 channels, Opus don't correlate channels,
but it does now if the input stream is Ambisonics (and if the Ambisonics
mode, disabled by default, is compiled in).
2. The next question is what ogg channel mapping and consequently
real-world browsers allow...
But in some sense the hack you did is known. (More complicated is
maybe to make it work...)
I tried only with 4 channels. It worked. I don't know if browsers are
now capable to support more than 8 channels. If the Octomic is getting
popular with VR content producers, maybe browsers will start supporting
streams with more than 8 channels (without systematically down-mixing
them to stereo).
3. If they already plan to issue some ogg ambisonics standard (using
ogg opus of course) since at least 2016: You also need an associated
mastering standard, which would not change or compress any audio data.
Correct?
So what is “political” about extending the channel count of FLAC?
Multi-channel still mean Dolby 5.1 or 7.1. There's an inertia because
"standards" were designed as vendor lock-ins.
Compromise proposal:
4. So let’s maybe use .wav or .caf for the “mastering format”.
Microsoft and Apple already allow more than 8 channels... 🤔
Sure. Lossy codecs are not suited for mastering.
P.S.: “Joint stereo” you could classify as parametric coding.
Ok.
Marc
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