On Mon, 2014-09-15 at 14:00 +1200, Eliot Blennerhassett wrote: 
> On 15/09/14 12:32, Adrian Mageanu wrote:
> 
> > What exactly should I look for in /dev/snd* ?
> 
> You'd see files corresponding to each device present
> 
> E.g. when I plug in  a usb webcam (laptop has inbuilt also)
> The following files appear:
> 
> pcmC1D0c  - the capture device C1 = card#1, D0 -> Device#0, 'c'->Capture
> controlC1 - The control device
> 
> ==============================================
> To test whether any audio comes from your hardware.
> 
> List the devices
> $ arecord -l
> 
> > **** List of CAPTURE Hardware Devices ****
> > card 0: PCH [HDA Intel PCH], device 0: ALC269VC Analog [ALC269VC Analog]
> >   Subdevices: 1/1
> >   Subdevice #0: subdevice #0
> > card 1: Camera [USB 2.0 Camera], device 0: USB Audio [USB Audio]
> >   Subdevices: 1/1
> >   Subdevice #0: subdevice #0
> 
> Record from the appropriate device, in my case #1
> 
> $ arecord -vv -fcd -Dplughw:1
> 
> This should display some configuration information, then a basic real
> time level graph on the terminal.
> ===============================================
> If the above tests show that there is a device present, and it is
> generating some non-zero audio data, then move on up the stack.
> 
> I.e. suspect pulseaudio or guvcview itself.
> 
> You could try
> 1. Restart pulseaudio
> 
> $ pulseaudio --kill
> pulseaudio will probably restart automatically (check with ps -C pulseaudio)
> 
> Then you can look at sources and their states
> $ pactl list short sources
> 
> > $ pactl list short sources
> > 0   alsa_output.pci-0000_00_1b.0.analog-stereo.monitor      
> > module-alsa-card.c      s16le 2ch 44100Hz       SUSPENDED
> > 1   alsa_input.pci-0000_00_1b.0.analog-stereo       module-alsa-card.c      
> > s16le 2ch 44100Hz       SUSPENDED
> > 2   
> > alsa_input.usb-Sonix_Technology_Co.__Ltd._USB_2.0_Camera-02-Camera.analog-mono
> >   module-alsa-card.c      s16le 1ch 16000Hz       SUSPENDED
> 
> The SUSPENDED state changes to RUNNING when the device is in use.
> 
~# ls -l /dev/snd/* | grep -i web
lrwxrwxrwx 1 root root 12 Sep 15 19:20
usb-046d_HD_Pro_Webcam_C920_5419A86F-02 -> ../controlC2

:~# ls -l /dev/snd/controlC2
crw-rw---T+ 1 root audio 116, 9 Sep 15 19:20 /dev/snd/controlC2

my user is in the audio group

~$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: SB [HDA ATI SB], device 0: ALC889 Analog [ALC889 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: SB [HDA ATI SB], device 2: ALC889 Analog [ALC889 Analog]
  Subdevices: 2/2
  Subdevice #0: subdevice #0
  Subdevice #1: subdevice #1
card 2: C920 [HD Pro Webcam C920], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 3: SAA7134 [SAA7134], device 0: SAA7134 PCM [SAA7134 PCM]
  Subdevices: 1/1
  Subdevice #0: subdevice #0


With webcam mike unmute:

~$ arecord -v -f cd -D plughw:2,0 -d 10 test.wav
Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz,
Stereo
Plug PCM: Rate conversion PCM (32000, sformat=S16_LE)
Converter: libspeex (builtin)
Protocol version: 10002
Its setup is:
  stream       : CAPTURE
  access       : RW_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 2
  rate         : 44100
  exact rate   : 44100 (44100/1)
  msbits       : 16
  buffer_size  : 22050
  period_size  : 5512
  period_time  : 125000
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 5512
  period_event : 0
  start_threshold  : 1
  stop_threshold   : 22050
  silence_threshold: 0
  silence_size : 0
  boundary     : 6206523236469964800
Slave: Hardware PCM card 2 'HD Pro Webcam C920' device 0 subdevice 0
Its setup is:
  stream       : CAPTURE
  access       : MMAP_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 2
  rate         : 32000
  exact rate   : 32000 (32000/1)
  msbits       : 16
  buffer_size  : 16001
  period_size  : 4000
  period_time  : 125000
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 4000
  period_event : 0
  start_threshold  : 1
  stop_threshold   : 16001
  silence_threshold: 0
  silence_size : 0
  boundary     : 9007762204694413312
  appl_ptr     : 0
  hw_ptr       : 0


I get nothing when I play back test.wav.

When trying with the front microphone (from headphones)

~$ arecord -v -f cd -D plughw:0,0 -d 10 test.wav
Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz,
Stereo
Plug PCM: Hardware PCM card 0 'HDA ATI SB' device 0 subdevice 0
Its setup is:
  stream       : CAPTURE
  access       : RW_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 2
  rate         : 44100
  exact rate   : 44100 (44100/1)
  msbits       : 16
  buffer_size  : 16384
  period_size  : 4096
  period_time  : 92879
  tstamp_mode  : NONE
  period_step  : 1
  avail_min    : 4096
  period_event : 0
  start_threshold  : 1
  stop_threshold   : 16384
  silence_threshold: 0
  silence_size : 0
  boundary     : 4611686018427387904
  appl_ptr     : 0
  hw_ptr       : 0


when I play back test.wav I can hear myself

Killing pulseaudio did not make any difference. It restarted by itself.

~$ pactl list short sources
0 alsa_output.pci-0000_01_00.1.hdmi-stereo-extra1.monitor
module-alsa-card.c s16le 2ch 44100Hz SUSPENDED
1 alsa_output.pci-0000_00_14.2.analog-stereo.monitor module-alsa-card.c
s16le 2ch 44100Hz SUSPENDED
2 alsa_input.pci-0000_00_14.2.analog-stereo module-alsa-card.c s16le 2ch
44100Hz SUSPENDED
3 alsa_input.usb-046d_HD_Pro_Webcam_C920_5419A86F-02-C920.analog-stereo
module-alsa-card.c s16le 2ch 32000Hz SUSPENDED


What should be the next step please?


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