[gentoo-user] ALSA wizard...

[Jorge Almeida <jjalmeida@gmail.com>]

... desperately needed.

The setup:
-- a microphone connected to an audio interface, which connects to an
USB port in the computer. The interface works like a USB sound card,
at least regarding sound capture. It works: I can record my voice with
arecord into a wav file, and then play the file with aplay.
-- a (motherboard) sound card with a toslink output connected to an
external DAC/amplifier. It works: playing wav, youtube, etc.

The problem:
I need to use it for voice chat. I tried slack and discord (the latter
both via browser and app--there's a package in portage--, the former
only via browser). No sound, neither outbound nor inbound.
None of these programs provides a way to tell them which devices to
use, so I assume they just go for some default.
I don't have a .asoundrc file. Contents of /etc/alsa/conf.d/ are not
customized.
Maybe some ALSA wiz that happens to be familiar with discord can
suggest something?

Thanks

Jorge Almeida

$ cat /proc/asound/devices
  1:        : sequencer
  2: [ 0- 0]: digital audio playback
  3: [ 0- 0]: digital audio capture
  4: [ 0- 1]: digital audio playback
  5: [ 0- 2]: digital audio capture
  6: [ 0- 3]: digital audio playback
  7: [ 0]   : control
  8: [ 1- 0]: digital audio playback
  9: [ 1- 0]: digital audio capture
 10: [ 1]   : control
 33:        : timer

$ arecord -L
null
    Discard all samples (playback) or generate zero samples (capture)
sysdefault:CARD=PCH
    HDA Intel PCH, Generic Analog
    Default Audio Device
front:CARD=PCH,DEV=0
    HDA Intel PCH, Generic Analog
    Front speakers
usbstream:CARD=PCH
    HDA Intel PCH
    USB Stream Output
sysdefault:CARD=CODEC
    USB Audio CODEC, USB Audio
    Default Audio Device
front:CARD=CODEC,DEV=0
    USB Audio CODEC, USB Audio
    Front speakers
surround21:CARD=CODEC,DEV=0
    USB Audio CODEC, USB Audio
    2.1 Surround output to Front and Subwoofer speakers
surround40:CARD=CODEC,DEV=0
    USB Audio CODEC, USB Audio
    4.0 Surround output to Front and Rear speakers
surround41:CARD=CODEC,DEV=0
    USB Audio CODEC, USB Audio
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=CODEC,DEV=0
    USB Audio CODEC, USB Audio
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=CODEC,DEV=0
    USB Audio CODEC, USB Audio
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=CODEC,DEV=0
    USB Audio CODEC, USB Audio
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=CODEC,DEV=0
    USB Audio CODEC, USB Audio
    IEC958 (S/PDIF) Digital Audio Output
usbstream:CARD=CODEC
    USB Audio CODEC
    USB Stream Output

$ aplay -L
null
    Discard all samples (playback) or generate zero samples (capture)
sysdefault:CARD=PCH
    HDA Intel PCH, Generic Analog
    Default Audio Device
front:CARD=PCH,DEV=0
    HDA Intel PCH, Generic Analog
    Front speakers
surround21:CARD=PCH,DEV=0
    HDA Intel PCH, Generic Analog
    2.1 Surround output to Front and Subwoofer speakers
surround40:CARD=PCH,DEV=0
    HDA Intel PCH, Generic Analog
    4.0 Surround output to Front and Rear speakers
surround41:CARD=PCH,DEV=0
    HDA Intel PCH, Generic Analog
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=PCH,DEV=0
    HDA Intel PCH, Generic Analog
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=PCH,DEV=0
    HDA Intel PCH, Generic Analog
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=PCH,DEV=0
    HDA Intel PCH, Generic Analog
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=PCH,DEV=0
    HDA Intel PCH, Generic Digital
    IEC958 (S/PDIF) Digital Audio Output
hdmi:CARD=PCH,DEV=0
    HDA Intel PCH, Generic Digital
    HDMI Audio Output
usbstream:CARD=PCH
    HDA Intel PCH
    USB Stream Output
sysdefault:CARD=CODEC
    USB Audio CODEC, USB Audio

I know iec958:CARD=CODEC,DEV=0 is the appropriate device for capture
and that iec958:CARD=PCH,DEV=0 is the appropriate device for playback,
because it's what works with -D.