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.

Takashi