PulseAudio usually does a pretty good job of determining what ALSA devices are available and setting them up automatically. When it doesn't, I'm not clear how this seemingly automatic linkage occurs. Is it a push where ALSA tells PulseAudio about the devices or a pull where PulseAudio determines from the ALSA configuration? Let's say you've got 3 audio 'cards': A, B and C. aplay -l shows all three (assume all three are working as expected via aplay) but pacmd list-cards only shows A and B. If you only wanted PulseAudio to use B and C, how would you get PulseAudio to remove A and add C? I assume this would be done via pacmd and/or changing PA's startup configuration files but I'm not clear as to how exactly to do this.

  • Without looking up details: Pulseaudio executes a startup script, which calls modules to either include all ALSA hardware (default), or specific ALSA cards (you need to modify the script accordingly, and use a different module). – dirkt Oct 8 '18 at 14:59

I think that modules are responsible for adding devices. E.g. there is one called module-udev-detect, and if I do pacmd list-cards in my system, I see module-udev-detect.discovered = "1" in two out of the three. The third one is a bluetooth device, so I guess that one comes from the bluez5 module.

Looking at the web a bit, you can make pulseaudio ignore a device coming from udev by setting ENV{PULSE_IGNORE}="1" in a udev rule. See

I guess that for bluetooth you'd have to fiddle with bluez, to ignore the device.

As to why a device can get ignored, that can be because it was locked (alsa devices can only be open once) when pulseaudio tried to open it.

Edit from @blihp:

To force PulseAudio to attempt to use an audio device, add an entry to /etc/pulse/default.pa:

load-module module-alsa-sink device=plughw:<card#>,<device#>

(replace <card#>,<device#> with the specific hardware for your system such as 0,1)

  • If you accept my minor edits (fixed typo and added final bit regarding forcing PulseAudio to use device), I think you've got it. Thanks... that gave me the nudge in the right direction I needed. – blihp Oct 14 '18 at 14:17
  • @blihp done . . . – V13 Oct 14 '18 at 14:35

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