admin:linux:sound [~wiki]

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.
====== Linux Sound ======
  * [[https://github.com/hastinbe/i3-volume|i3-volume]] – script to change volume and display OSD.

===== Music server =====

[[http://mopidy.com/|Mopidy]]: [[https://github.com/dirkgroenen/mopidy-mopify|Mopify (Spotify für Mopidy, Webinterface)]]

===== PulseAudio =====
  * [[https://github.com/lawl/NoiseTorch|NoiseTorch]] – virtual microphone that suppresses noise

===== Pipewire =====
Next generation sound server, meant to succeed PulseAudio's janky architecture.

  * [[https://github.com/wwmm/pulseeffects|PulseEffects]] – Effects GUI for Pipewire, older versions support PulseAudio as well.
  * [[https://gitlab.freedesktop.org/ryuukyu/helvum|Helvum]] – GTK-based patchbay for pipewire, inspired by the JACK tool [[https://kx.studio/Applications:Catia|catia]].
  * [[https://gitlab.freedesktop.org/rncbc/qpwgraph|qpwgraph]] – graph manager for PipeWire, very similar to QjackCtl.
  * pw-viz – visualise Pipewire inputs/outputs/routing.
==== Commands ====
<code bash>
# toggle mute mode
pactl set-sink-mute 0 toggle
# increase volume of default sink (=sound target) in 1% steps
# warning: can exceed 100%.
pactl set-sink-volume @DEFAULT_SINK@ +1%
</code>

===== ALSA =====

==== Commands ====

<code bash>
# lower volume and unmute
amixer set Master 5%- unmute

# raise volume and unmute
amixer set Master 5%+ unmute
</code>

==== Scripts ====

<file bash automute.sh>
#!/bin/sh
# check auto-mute state
amixer -c 1 sget "Auto-Mute Mode" | grep "Item0: 'Disabled'"
# $? is 0 if auto-mute is disabled
# $? is 1 if auto-mute is enabled
if [ "$?" -eq "0" ]; then
    amixer -c 1 sset "Auto-Mute Mode" Enabled
else
    amixer -c 1 sset "Auto-Mute Mode" Disabled
fi
</file>

===== Troubleshooting =====

=== suddenly no sound with USB sound card ===
<code>$ alsamixer
cannot open mixer: No such file or directory</code>

<file - /etc/modprobe.d/alsa-base.conf># Keep snd-usb-audio from beeing loaded as first soundcard
options snd-usb-audio index=-2</file>

<code>-2 → 0</code>

=== bad audio quality / crackling / lag ===

Crackling or popping in PipeWire usually comes from buffer underruns or resampling issues.

== Causes ==
  * Missing realtime scheduling (no rtkit)
  * Wrong sample rate or small quantum
  * CPU power-saving or load spikes
  * Aggressive resampling between 44.1 kHz and 48 kHz

== Fix: Install realtime support ==
<code bash>
sudo pacman -S rtkit
</code>

== Fix: Edit PipeWire config ==
<file /etc/pipewire/pipewire.conf>
default.clock.rate = 48000
default.clock.allowed-rates = [ 44100 48000 ]
default.clock.quantum = 1024
default.clock.min-quantum = 512
default.clock.max-quantum = 2048
</file>

== Fix (Optional): Adjust WirePlumber ALSA settings ==
<file ~/.config/wireplumber/main.lua.d/50-alsa-config.lua>
["api.alsa.period-size"] = 1024
["api.alsa.headroom"] = 8192
</file>

== Restart PipeWire ==
<code bash>
systemctl --user restart pipewire pipewire-pulse wireplumber
</code>

== Testing ==
  * Verify settings:
    <code>pw-metadata -n settings 0</code>
  * Play tone:
    <code>speaker-test -t sine -f 440</code>
  * Watch logs:
    <code>journalctl --user -u pipewire.service -f</code>
  * Monitor:
    <code>pw-top</code>

If crackling persists, increase `quantum` or disable CPU power-saving.

=== audiophile settings for pulseaudio ===

Might cause crackling when CPU load is high!

<file conf ~/.config/pulse/daemon.conf>resample-method = soxr-mq
flat-volumes = no
default-sample-format = s24le
default-sample-rate = 96000</file>