[FFmpeg-devel] [PATCH] decklink: support all valid numbers of audio channels

Nicolas George george at nsup.org
Sun Dec 20 14:53:41 CET 2015

Le decadi 30 frimaire, an CCXXIV, Matthias Hunstock a écrit :
> SDI just transports 16 mono channels of audio, without any implied
> semantic of what is in there. So the closest matching layouts are 2.0,
> 8.0 and 16.0, if they existed.

That does not mean anything. The channel layout called 5.1 "exists" because
the convention has made it the short name for "front left + front right +
front center + rear left + rear right + subwoofer". It is just a convenient

"16.0" does not "exist" because there is not, at this time, an audio
configuration with 16 channels that is widely used.

For the same reason, "8.0" does not "exist" because the only common
configurations with 8 channels are the variants of 7.1, i.e. with a

I have absolutely no idea what decklinks cards actually do, and in
particular where they take their audio. If there is a layout that is way
more common than anything else, then it makes sense to have it the default.
Otherwise, it is better to leave the layout unspecified to avoid leaking
false information in output files.


  Nicolas George
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