Re: [Alsa-user] snd-usb-audio, Webcam mic, 2nd sound device

[Dan G. <dan...@ya...>]

--- Clemens Ladisch <cl...@la...> wrote:
> Dan Garton wrote:
> > --- Clemens Ladisch <cl...@la...> wrote:
> > > Dan Garton wrote:
> > > > # modprobe snd-usb-audio
> > > >  ALSA ../alsa-kernel/usb/usbaudio.c:1980:
> 2:2:0 :
> > > > AS_GENERAL descriptor not found
> > >
> > > It seems your device isn't 100% compatible with
> the
> > > USB audio
> > > specification. Please post the output of "lsusb
> -v".
> >
> > Thanks for the response. I had thought that the
> device
> > was fully recognised, from the contents of the
> files
> > generated in
> > /proc/asound/card1/.
> >
> > Anyway here is the (complete) verbose lsusb
> output:
> > ...
> 
> Well, your device actually is compatible. The
> warning message above is
> caused by a bug in the driver, but shouldn't affect
> recording.
> 
> > When I try to record from the device, I get an
> empty
> > file:
> >
> > # arecord -D plughw -t wav -d 5 test.wav
> >
> > test.wav then contains no data.
> 
> "plughw" defaults to the first sound card. Please
> try:
> 
>     arecord -D plughw:1 -r 44100 -c 1 -f S16_LE -v
> -t wav -d 5 test.wav

Yes, this works. I have the mic recording now with
arecord.

yukka root # arecord -D plughw:1 -r 44100 -c 1 -f
S16_LE -v -t wav -d 30 test.wav

Recording WAVE 'test3.wav' : Signed 16 bit Little
Endian, Rate 44100 Hz, Mono
Plug PCM: Hardware PCM card 1 'Camera' device 0
subdevice 0

Its setup is:
stream       : CAPTURE
access       : RW_INTERLEAVED
format       : S16_LE
subformat    : STD
channels     : 1
rate         : 44100
exact rate   : 44100 (44100/1)
msbits       : 16
buffer_size  : 22050
period_size  : 5513
period_time  : 125011
tick_time    : 2000
tstamp_mode  : NONE
period_step  : 1
sleep_min    : 0
avail_min    : 5513
xfer_align   : 5513
start_threshold  : 1
stop_threshold   : 22050
silence_threshold: 0
silence_size : 0
boundary     : 1445068800

I found that there were many pops and clicks in the
sound when I recorded with the capture level at 100%
(if I tried to play such a file, raising the playback
PCM level to over 81% cut out the sound entirely).
Lowering the mixer capture level to around 77%
improved this a lot, producing far less pops and
crackles.

yukka root # amixer -c 1
Simple mixer control 'Mic',0
  Capabilities: cvolume cswitch cswitch-joined
  Capture channels: Mono
  Limits: Capture 0 - 55
  Mono: Capture 40 [73%] [on]
Simple mixer control 'Auto Gain Control',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]

At the moment Gnomemeeting is still refusing to be
able to open /dev/sound/dsp1 to use it as a capture
source - God knows why.

One question: why do I have to modprobe snd-usb-audio
manually for the webcam, when my PCI FM801-based card
is recognised and has modules loaded on boot-up?
My ALSA modules conf file is in one of my earlier posts.

__________________________________
Do you Yahoo!?
SBC Yahoo! DSL - Now only $29.95 per month!
http://sbc.yahoo.com