[alsa-devel] [Q] playing / recording mono on a stereo-only hardware

Michael Trimarchi trimarchi at gandalf.sssup.it
Sat Jan 30 17:29:05 CET 2010

Guennadi Liakhovetski wrote:
> Hi
> I know this question belongs rather to alsa-users, and I did ask it there, 
> but got no solution so far. Maybe someone here can help.
> The recently posted SuperH SIU driver only supports stereo playback and 
> capture (channels_min = channels_max = 2). Is there a way to tell alsa-lib 
> to duplicate the mono-channel during playback and to mix recorded channels 
> (or use one of them), if mono recording is requested?
I'm not an expert but I think that you can use plughw support of alsa-lib

pcm.record {
       type plug
       slave {
               pcm record_hw
       route_policy average
       rate_converter "linear"

I think that automatically change rate and channel for supporting mono 
channel too


> Thanks
> Guennadi
> ---
> Guennadi Liakhovetski, Ph.D.
> Freelance Open-Source Software Developer
> http://www.open-technology.de/
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