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# ls -hal /dev/snd/
total 0
drwxr-xr-x  2 root root       320 2009-07-29 10:21 .
drwxr-xr-x 14 root root      4.9K 2009-07-29 12:26 ..
crw-rw----  1 root user0 116,   0 2009-07-29 10:21 controlC0
crw-rw----  1 root user1 116,  32 2009-07-29 10:21 controlC1
crw-rw----  1 root user2 116,  64 2009-07-29 10:21 controlC2
crw-rw----  1 root user3 116,  96 2009-07-29 10:21 controlC3
crw-rw----  1 root user0 116,  24 2009-07-29 10:21 pcmC0D0c
crw-rw----  1 root user0 116,  16 2009-07-29 11:26 pcmC0D0p
crw-rw----  1 root user1 116,  56 2009-07-29 10:21 pcmC1D0c
crw-rw----  1 root user1 116,  48 2009-07-29 10:40 pcmC1D0p
crw-rw----  1 root user2 116,  88 2009-07-29 10:21 pcmC2D0c
crw-rw----  1 root user2 116,  80 2009-07-29 12:26 pcmC2D0p
crw-rw----  1 root user3 116, 120 2009-07-29 10:21 pcmC3D0c
crw-rw----  1 root user3 116, 112 2009-07-29 10:37 pcmC3D0p
crw-rw----  1 root audio 116,   1 2009-07-29 10:21 seq
crw-rw----  1 root audio 116,  33 2009-07-29 10:21 timer

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# cat /proc/asound/cards
 0 [audiodevice0   ]: USB-Audio - C-Media USB Audio Device
                      C-Media USB Audio Device    at usb-0000:00:13.0-1, full speed
 1 [audiodevice1   ]: USB-Audio - C-Media USB Audio Device
                      C-Media USB Audio Device    at usb-0000:00:13.0-2, full speed
 2 [audiodevice2   ]: USB-Audio - C-Media USB Audio Device
                      C-Media USB Audio Device    at usb-0000:00:13.3-1, full speed
 3 [audiodevice3   ]: USB-Audio - C-Media USB Audio Device
                      C-Media USB Audio Device    at usb-0000:00:13.3-2, full speed

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# cat /home/user0/.asoundrc
pcm.!default {
   type plug
   slave.pcm dmixer
}
pcm.dmixer {
   type dmix
   ipc_key 2048
   slave.pcm hw:audiodevice0
}
ctl.dmixer {
   type hw
   card audiodevice0
}
pcm.dsp {
    type plug
    slave.pcm dmixer
}
ctl.mixer {
    type hw
    card audiodevice0
}

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su user0

# This is the issue. how can I configure the asoundrc so that arecord
# uses audiodevice0 by default like speaker-test already does for playing.

$ arecord -v -f S16_LE -r 44100 ~/record1.wav
ALSA lib pcm_dmix.c:947:(snd_pcm_dmix_open) The dmix plugin supports only playback stream
arecord: main:608: audio open error: Invalid argument

$ arecord -v -f S16_LE -r 44100 -D hw:audiodevice0 ~/record0.wav
Recording WAVE '/home/user0/record0.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Mono
Hardware PCM card 0 'C-Media USB Audio Device   ' 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
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 5513
  period_event : 0
  start_threshold  : 1
  stop_threshold   : 22050
  silence_threshold: 0
  silence_size : 0
  boundary     : 6206523236469964800
  appl_ptr     : 0
  hw_ptr       : 0
^CAborted by signal Interrupt...

$ ls -hal ~/record*.wav
-rw-r----- 1 user0 user0 1.8M 2009-07-29 12:56 /home/user0/record0.wa

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su -c "speaker-test -c 2 & speaker-test -c 2 &" user0

------------------------------------------------------------------------