A simple way to fix audio on GNU/Linux

First written on October 23, 2022

I wanted to set HDMI as default output and the webcam’s microphone as default input. Using ALSA directly didn’t work in all cases so I tried with Pulseaudio.

First attempt: use ALSA #

I did several tests to see if it was feasable with ALSA. Turns out it isn’t so straight forward.

Output #

get a list of all output devices

aplay -l

which in my case results in

**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC887-VD Analog [ALC887-VD Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 1: ALC887-VD Digital [ALC887-VD Digital]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 7: HDMI 1 [HDMI 1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 8: HDMI 2 [HDMI 2]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 9: HDMI 3 [HDMI 3]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 10: HDMI 4 [HDMI 4]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

this configuration sets Intel’s HDMI audio as default device. I had to go through all the HDMI Intel devices to know which one to choose. See this Arch wiki page. Add this to ~/.asoundrc
```
pcm.!default {
    type hw
    card 0
    device 8
}
defaults.pcm.card 0
defaults.pcm.device 8
defaults.ctl.card 0
```

Input #

Now, list all the input devices

arecord -l

which outputs

**** List of CAPTURE Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC887-VD Analog [ALC887-VD Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: PCH [HDA Intel PCH], device 2: ALC887-VD Alt Analog [ALC887-VD Alt Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: STK1160 [STK1160], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: HD3000 [Microsoft® LifeCam HD-3000], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

this configuration is used to set the webcam’s audio as default capture device. Add this to ~/.asoundrc (this does not work in conjunction with the previous ALSA configuration)

pcm.usb
{
    type hw
    card HD3000
}

pcm.!default
{
    type asym
    playback.pcm
    {
        type plug
        slave.pcm "usb"
    }
    capture.pcm
    {
        type plug
        slave.pcm "usb"
    }
}

Some applications such as Firefox will not see these configurations and will continue to use the system’s default audio devices. Good luck accessing a non default microphone or playing back on HDMI on a browser. This page explains how to deal with multiple audio cards as well as ordering them in the kernel.

Second attempt: use Pulseaudio #

Pulseaudio is used a layer on top of ALSA. There is no need to setup devices manually with configuration files and applications have less difficuly accessing the audio.

install Pulseaudio and enable the daemon

apt-get install pulseaudio pavucontrol pamix
systemctl --user enable pulseaudio.service

get the names and kill the applications still accessing ALSA. Run this as root
```
fuser -v /dev/snd/*
```
backup your ALSA configuration, just in case
```
mv ~/.asoundrc ~/.asoundrc.bak
```

start the service

systemctl --user start pulseaudio.service

open the mixers and enjoy
```
pavucontrol
pamix
```

Improvements #

Enable High Quality Audio on Linux | by Gamunu Balagalla | Medium

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