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

[Guennadi Liakhovetski]

On Tue, 2 Feb 2010, Michael Trimarchi wrote:

> Guennadi Liakhovetski wrote:
> > (re-adding the list)
> > 
> > On Tue, 2 Feb 2010, Michael Trimarchi wrote:
> > 
> >   
> > > Hi,
> > > 
> > > Guennadi Liakhovetski wrote:
> > >     
> > > > On Sat, 30 Jan 2010, Michael Trimarchi wrote:
> > > > 
> > > >         
> > > > > 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 for the snippet, but, I'm afraid, it didn't help either.
> > > >         
> > > Sorry can you explain a little bit more why it doesn't help you?
> > >     
> > 
> > I certainly gladly would explain this, if only I knew... It just doesn't
> > change anything. Are you using it anywhere? If yes, with which hardware
> > configuration and software (alsa-lib) versions?
> >   
> alsa-lib 1.0.16

1.0.22 here.

> #define BUILD_PCM_PLUGIN_RATE "1"
> #define BUILD_PCM_PLUGIN_ROUTE "1"

Yes, have these in include/config.h too.

> Hardware android openmoko gta02. Test it with arecord 1 month ago

Ok, looks like openmoko has a few configurations, of which some are just 
mono, and the I2S is, of course, stereo only. So, did this work with the 
HiFi (I2S) interface and not with bluetooth?

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