[alsa-devel] How to define card specific pcm devices?

Tanu Kaskinen tanuk at iki.fi
Wed Sep 5 07:41:02 CEST 2012

On Wed, 2012-08-29 at 09:44 +0800, Raymond Yau wrote:
> strictly speaking your mic is not a true stereo mic and the channel
> map is [left, null] instead of the normal map [left,right] of line-in
> or stereo mic

I think specifying the channel map like you suggest would be a good
solution. Supporting it would require some extra work in PulseAudio, but
I think PulseAudio will anyway have to be extended to query the channel
map information from UCM.

Now the problem is that UCM doesn't provide the channel map information
at all. Should the channel map be provided in the device "Value"
section? Like this:

SectionDevice."my-mono-mic" {


        Value {
                # Does this value become redundant if
                # the "CaptureChannelMap" value is added?
                CaptureChannels "2"

		# Channel names match the constants in
                # Takashi's proposed channel map API
                CaptureChannelMap "FL, NA"


Opinions? (Liam added to CC - am I right in that you should be CC'd in
all UCM related discussions?)


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