[alsa-devel] Channel map API patches: to be 3.7 or not to be?

Takashi Iwai tiwai at suse.de
Tue Sep 11 14:24:09 CEST 2012

At Tue, 11 Sep 2012 14:19:49 +0200,
Clemens Ladisch wrote:
> Takashi Iwai wrote:
> > BTW, this reminds me of an open question:
> >   is it useful to add SND_CHMAP_MONO, or is it just redundant?
> >
> > It's nothing but indicating a mono channel without any channel
> > position, so I supposed SND_CHMAP_UNKNOWN being sufficient.  OTOH,
> > SND_CHMAP_MONO would give a clear sign of mono streams while
> > SND_CHMAP_UNKNOWN could be used for any other exceptional purposes.
> What would it be used for?
> Labeling surround channels is necessary for reordering them or for doing
> up/downmixing.  A "mono" channel, however, does not appear to have any
> semantic difference from a single "unknown" channel.

Right, that's the current status.  OTOH, labeling it as "mono" makes
clear that it's an unaligned mono stream. i.e. it shows the purpose of 
the stream by itself.

Well, I'm not for introducing yet another definition.  Just stumbled
on it, and would like to know opinions from others.



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