[alsa-devel] RFC: PCM extra attributes

Takashi Iwai tiwai at suse.de
Fri Jun 19 11:14:38 CEST 2009

At Fri, 19 Jun 2009 10:54:15 +0200,
Florian Faber wrote:
> Takashi,
> > An important note is that I'm planning to use this framework for
> > getting/setting the PCM (surround) channel mapping.
> I don't understand what this means. Who maps what on what and why?

It's a mapping of surround channels.  Right now, ALSA assumes (usually)
the order of channels like front-left, front-rear, surround-left,
surround-rear, center, LFE, ...  But this really depends on the
device.  Some (or many) need FL/FR/C/LFE/SR/SR order, for example.
And, some devices can allow you even to reassign the channel map.

This is likely an additional information, which not all drivers have
to provide.


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