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

[Raymond Yau]

2010/2/5 Guennadi Liakhovetski <g.liakhovetski at gmx.de>

> On Thu, 4 Feb 2010, Raymond Yau wrote:
>
> I would see your reply sooner, if you used reply-to-all.
>
> > if LIBASOUND_DEBUG = 1 cannot tell you which parameter fail in
> hw_params() ,
> > you will need to define RULES_DEBUG in alsa-kernel/core/pcm_native.c and
> > compile driver with debug=verbose
> >
> > -#undef RULES_DEBUG
> > +#define RULES DEBUG 1
>
> That's already on too. Not sure what you mean by "compile driver with
> debug=verbose," supposedly, some kernel ALSA debug parameter. Since this
> is my driver, I can certainly add any debugging there, but it seems
> obvious to me, that the kernel is still getting a mono configuration,
> which shouldn't be the cae.
>
> > you can find out how ALSA refine the hw parameters by examing the system
> log
>
> If you mean "dmesg" output, then, as I said, there isn't much to look for
> there - the kernel is configured for mono...
>
> Thanks
> Guennadi
>


your output is quite different from mine

arecord -v -f cd -c 1 -d 30 -r 8000 -Dplughw:1,0 any.wav
Recording WAVE 'any.wav' : Signed 16 bit Little Endian, Rate 8000 Hz, Mono
Plug PCM: Route conversion PCM (sformat=S16_LE)
  Transformation table:
    0 <- 0*0.5 + 1*0.5
Its setup is:
  stream       : CAPTURE
  access       : RW_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 1
  rate         : 8000
  exact rate   : 8000 (8000/1)
  msbits       : 16
  buffer_size  : 3968
  period_size  : 992
  period_time  : 124000
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 992
  period_event : 0
  start_threshold  : 1
  stop_threshold   : 3968
  silence_threshold: 0
  silence_size : 0
  boundary     : 2080374784
Slave: Hardware PCM card 1 'HDA Intel' device 0 subdevice 0
Its setup is:
  stream       : CAPTURE
  access       : MMAP_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 2