[FFmpeg-devel] [PATCH] ALSA: implement channel layout for playback.

Carl Eugen Hoyos cehoyos
Tue Mar 15 23:02:29 CET 2011


Nicolas George <nicolas.george <at> normalesup.org> writes:

> Le quartidi 24 vent?se, an CCXIX, Carl Eugen Hoyos a ?crit :
> > I am not sure if this is correct (I don't know of a _BACK sample), but it
> > should at least also include AV_CH_LAYOUT_5POINT1 (that's what I tested
> > successfully).
> Theoretically, 5POINT1 and 5POINT1_BACK are different. In practice, I
> suspect most projects do not distinguish them.

What I tried to say was: In my tests, your patch was correct if I did
s/AV_CH_LAYOUT_5POINT1_BACK/AV_CH_LAYOUT_5POINT1 - since I did not find a _BACK
sample, I don't know if it exists and how it should be dealt with.

> So I am undecided. What do other people think about that: silently accept
> side left+right as rear left+right?
> > I don't disagree, but if 4 channel output was requested, it should either
> > setsurround to silence or map the back channel to both surround channels.
> > What should be done with centre in this case?
> The current behaviour with my patch is to print a warning and let the used
> deal with it any way he wants. I think that is correct. Except that there is
> currently no good way to deal with it, but this is another issue.

But we could print a warning and still map the back channel to the two surround
channels (or is this plain wrong?) and centre to L+R (or just remove it).

Carl Eugen

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