PulseAudio

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PulseAudio is a sound server commonly used by desktop environments like GNOME or KDE. It serves as a proxy to sound applications using existing kernel sound components like ALSA or OSS. Since ALSA is included in Arch Linux by default, the most common deployment scenarios include PulseAudio with ALSA.

Installation

Install the pulseaudio package.

Some PulseAudio modules have been split from the main package and must be installed separately if needed:

Note: Some confusion can be made between ALSA and PulseAudio. ALSA includes both Linux kernel component with sound card drivers, and a userspace component, libalsa.[1] PulseAudio builds only on the kernel component, but offers compatibility with libalsa through pulseaudio-alsa.[2]

Front-ends

There is a number of front-ends available for controlling the PulseAudio daemon:

Configuration

Configuration files

Merge-arrows-2.pngThis article or section is a candidate for merging with PulseAudio/Configuration.Merge-arrows-2.png

Notes: Configuration should stay in the main article, so the linked page should be merged here. Split #Troubleshooting instead if this page is found too long. (Discuss in Talk:PulseAudio#Abandoned draft)

By default, PulseAudio is configured to automatically detect all sound cards and manage them. It takes control of all detected ALSA devices and redirect all audio streams to itself, making the PulseAudio daemon the central configuration point. The daemon should work mostly out of the box, only requiring a few minor tweaks.

PulseAudio will first look for configuration files in home directory ~/.config/pulse, then in system wide /etc/pulse.

PulseAudio runs as a server daemon that can run either system-wide or on per-user basis using a client/server architecture. The daemon by itself does nothing without its modules except to provide an API and host dynamically loaded modules. The audio routing and processing tasks are all handled by various modules. You can find a detailed list of all available modules at Pulseaudio Loadable Modules. To enable them you can just add a line load-module <module-name-from-list> to ~/.config/pulse/default.pa.

Tip:
  • It is strongly suggested not to edit system wide configuration files, but rather edit user ones. Create the ~/.config/pulse directory, then copy the system configuration files into it and edit according to your need.
  • Make sure you keep user configuration in sync with changes to the packaged files in /etc/pulse/. Otherwise, PulseAudio may refuse to start due to configuration errors.
  • There is no need to add your user to audio group, as it uses udev and logind to dynamically give access to the currently "active" user

daemon.conf

Defines base settings like the default sample rates used by modules, resampling methods, realtime scheduling and various other settings related to the server process. These can not be changed at runtime without restarting the PulseAudio daemon. The defaults are sensible for most users.

Notable configuration options
Option Description
system-instance Run the daemon as a system-wide instance. Highly discouraged as it can introduce security issues. Useful on (headless) systems that have no real local users. Defaults to no.
resample-method Which resampler to use when audio with incompatible sample rates needs to be passed between modules (e.g. playback of 96kHz audio on hardware which only supports 48kHz). The available resamplers can be listed with $ pulseaudio --dump-resample-methods. Choose the best tradeoff between CPU usage and audio quality for the present use-case.
Tip: In some cases PulseAudio will generate a high CPU load. This can happen when multiple streams are resampled (individually). If this is a common use-case in a workflow, it should be considered to create an additional sink at a matching sample rate which can then be fed into the main sink, resampling only once.
flat-volumes flat-volumes scales the device-volume with the volume of the "loudest" application. For example, raising the VoIP call volume will raise the hardware volume and adjust the music-player volume so it stays where it was, without having to lower the volume of the music-player manually. Defaults to yes upstream, but to no within Arch.
Note: The default behavior upstream can sometimes be confusing and some applications, unaware of this feature, can set their volume to 100% at startup, potentially blowing your speakers or your ears. This is why Arch defaults to the classic (ALSA) behavior by setting this to no.
default-fragments Audio samples are split into multiple fragments of default-fragment-size-msec each. The larger the buffer is, the less likely audio will skip when the system is overloaded. On the downside this will increase the overall latency. Increase this value if you have issues.

default.pa

This file is a startup script and is used to configure modules. It is actually parsed and read after the daemon has finished initializing and additionnal commands can be sent at runtime using $ pactl or $ pacmd. The startup script can also be provided on the command line by starting PulseAudio in a terminal using $ pulseaudio -nC. This will make the daemon load the CLI module and will accept the configuration directly from the command line, and output resulting information or error messages on the same terminal. This can be useful when debugging the daemon or just to test various modules before setting them permanently on disk. The manual page is quite self-explanatory, please consult man pulse-cli-syntax for the details of the syntax.

Tip:
  • Run $ pacmd list-sinks|egrep -i 'index:|name:' to list available sinks. The present default sink is marked with an asterisk.
  • Edit ~/.config/pulse/default.pa to insert/alter the set-default-sink command using the sink's name as the numbering cannot be guaranteed repeatable.

client.conf

This is the configuration file read by every PulseAudio client application. It is used to configure runtime options for individual clients. It can be used to set and configure the default sink and source statically as well as allowing (or disallowing) clients to automatically start the server if not currently running.

Configuration command

The main command to configure a server during runtime is $ pacmd. Run $ pacmd --help for a list options, or just run $ pacmd to enter the shell interactive mode and Ctrl+d to exit. All modifications will immediately be applied.

Once your new settings have been tested and meet your needs, edit the default.pa accordingly to make the change persistent. See PulseAudio/Examples for some basic settings.

Tip: leave the load-module module-default-device-restore line in the default.pa file untouched. It will allow you to restart the server in its default state, thus dismissing any wrong setting.

It is important to understand that the "sources" (processes, capture devices) and "sinks" (sound cards, servers, other processes) accessible and selectable through PulseAudio depend upon the current hardware "Profile" selected. These "Profiles" are those ALSA "pcms" listed by the command aplay -L, and more specifically by the command pacmd list-cards, which will include a line "index:", a list beginning "profiles:", and a line "active profile: <...>" in the output, among other things.

The "active profile" can be set with the command pacmd set-card-profile INDEX PROFILE, with no comma separating INDEX and PROFILE, where INDEX is just the number on the line "index:" and a PROFILE name is everything shown from the beginning of any line under "profile:" to just before the colon and first space, as shown by the command pacmd list-cards. For instance, pacmd set-card-profile 0 output:analog-stereo+input:analog-stereo.

It may be easier to select a "Profile" with a graphical tool like pavucontrol, under the "Configuration" tab, or KDE System Settings, "Multimedia/Audio and Video Settings", under the "Audio Hardware Setup" tab. Each audio "Card", which are those devices listed by the command aplay -l, or again by the command pacmd list-cards, will have its own selectable "Profile". When a "Profile" has been selected, the then available "sources" and "sinks" can be seen by using the commands pacmd list-sources and pacmd list-sinks. Note that the "index" of the available sources and sinks will change each time a card profile is changed.

The selected "Profile" can be an issue for some applications, especially the Adobe Flash players, typically /usr/lib/mozilla/plugins/libflashplayer.so and /usr/lib/PepperFlash/libpepflashplayer.so. Often, these Flash players will only work when one of the Stereo profiles is selected, and otherwise, will play video with no sound, or will simply "crash". When all else fails, you might try selecting a different profile.

Of course, when configuring some variation of Surround Sound in PulseAudio, the appropriate Surround profile will have to be selected, before Surround Sound will work, or in order to do things like remap the speaker channels.

Running

Since version 7.0, PulseAudio on Arch uses socket activation. By default, pulseaudio.socket is enabled for the systemd/User instance.

Note:
  • To disable pulseaudio.socket, make sure that $XDG_CONFIG_HOME/systemd/user/ exists and run systemctl --user mask pulseaudio.socket.
  • Many desktop environments autostart programs based on desktop files in the /etc/xdg/autostart/ directory. In this case, PulseAudio will be launched automatically regardless of the socket activation status.

For more information, see PulseAudio: Running.

Starting manually

PulseAudio can be manually started with:

$ pulseaudio --start

And stopped with:

$ pulseaudio --kill

Back-end configuration

ALSA

Install the pulseaudio-alsa package. It contains the necessary /etc/asound.conf for configuring ALSA to use PulseAudio.

Also install lib32-libpulse and lib32-alsa-plugins if you run a x86_64 system and want to have sound for 32-bit multilib programs like Wine, Skype and Steam.

To prevent applications from using ALSA's OSS emulation and bypassing PulseAudio (thereby preventing other applications from playing sound), make sure the module snd_pcm_oss is not being loaded at boot. If it is currently loaded (lsmod | grep oss), disable it by executing:

# rmmod snd_pcm_oss

ALSA/dmix without grabbing hardware device

Note: This section describes alternative configuration, which is generally not recommended.

You may want to use ALSA directly in most of your applications while still being able to use applications which require PulseAudio at the same time. The following steps allow you to make PulseAudio use dmix instead of grabbing ALSA hardware device.

  • Remove package pulseaudio-alsa, which provides compatibility layer between ALSA applications and PulseAudio. After this your ALSA apps will use ALSA directly without being hooked by Pulse.
  • Edit /etc/pulse/default.pa.
Find and uncomment lines which load back-end drivers. Add device parameters as follows. Then find and comment lines which load autodetect modules.
load-module module-alsa-sink device=dmix
load-module module-alsa-source device=dsnoop
# load-module module-udev-detect
# load-module module-detect
  • Optional: If you use kdemultimedia-kmix you may want to control ALSA volume instead of PulseAudio volume:
$ echo export KMIX_PULSEAUDIO_DISABLE=1 > ~/.kde4/env/kmix_disable_pulse.sh
$ chmod +x ~/.kde4/env/kmix_disable_pulse.sh
  • Now, reboot your computer and try running ALSA and PulseAudio applications at the same time. They both should produce sound simultaneously.
Use pavucontrol to control PulseAudio volume if needed.

OSS

There are multiple ways of making OSS-only programs output to PulseAudio:

ossp

Install ossp package and start osspd.service.

padsp wrapper

Programs using OSS can work with PulseAudio by starting it with padsp (included with PulseAudio):

$ padsp OSSprogram

A few examples:

$ padsp aumix
$ padsp sox foo.wav -t ossdsp /dev/dsp

You can also add a custom wrapper script like this:

/usr/local/bin/OSSProgram
#!/bin/sh
exec padsp /usr/bin/OSSprogram "$@"

Make sure /usr/local/bin comes before /usr/bin in your PATH.

GStreamer

Install gst-plugins-good, or gstreamer0.10-good-plugins if your intended program has a legacy GStreamer implementation.

OpenAL

OpenAL Soft should use PulseAudio by default, but can be explicitly configured to do so:
/etc/openal/alsoft.conf
drivers=pulse,alsa

libao

Edit the libao configuration file:

/etc/libao.conf
default_driver=pulse

Be sure to remove the dev=default option of the alsa driver or adjust it to specify a specific Pulse sink name or number.

Note: You could possibly also keep the libao standard of outputting to the alsa driver and its default device if you install pulseaudio-alsa since the ALSA default device then is PulseAudio.

Equalizer

Tango-view-refresh-red.pngThis article or section is out of date.Tango-view-refresh-red.png

Reason: As of pulseaudio-7.0-2, the module-equalizer-sink is unsupported, see Talk:PulseAudio#Equalizer module is unsupported. (Discuss in Talk:PulseAudio#)

PulseAudio has an integrated 10-band equalizer system. In order to use the equalizer do the following:

Install pulseaudio-equalizer:

Load equalizer sink and dbus-protocol module

$ pactl load-module module-equalizer-sink
$ pactl load-module module-dbus-protocol

GUI front-end

run:

$ qpaeq
Note: If qpaeq has no effect, install pavucontrol and change "ALSA Playback on" to "FFT based equalizer on ..." while the media player is running.

Load equalizer and dbus module on every boot

Edit the /etc/pulse/default.pa or ~/.config/pulse/default.pa file with your favorite editor and append the following lines:

### Load the integrated PulseAudio equalizer and D-Bus module
load-module module-equalizer-sink
load-module module-dbus-protocol
Note: The equalizer sink needs to be loaded after the master sink is already available.

Applications

QEMU

Merge-arrows-2.pngThis article or section is a candidate for merging with QEMU.Merge-arrows-2.png

Notes: QEMU is the most complex of the "applications" described in this section, merging to the main article would provide better context. (Discuss in Talk:PulseAudio#)

The audio driver used by QEMU is set with the QEMU_AUDIO_DRV environment variable:

$ export QEMU_AUDIO_DRV=pa

Run the following command to get QEMU's configuration options related to PulseAudio:

$ qemu-system-x86_64 -audio-help | awk '/Name: pa/' RS=

The listed options can be exported as environment variables, for example:

$ export QEMU_PA_SINK=alsa_output.pci-0000_04_01.0.analog-stereo.monitor
$ export QEMU_PA_SOURCE=input

Tango-edit-clear.pngThis article or section needs language, wiki syntax or style improvements.Tango-edit-clear.png

Reason: The following is not specific to PulseAudio. (Discuss in Talk:PulseAudio#)

To get list of the supported emulation audio drivers

$ qemu-system-x86_64 -soundhw help

To use e.g. ac97 driver for the guest use the -soundhw ac97 commnad with QEMU.

Note: Video graphic card emulated drivers for the guest machine may also cause a problem with the sound quality. Test one by one to make it work. You can list possible options with qemu-system-x86_64 -h | grep vga.

AlsaMixer.app

Make alsamixer.appAUR dockapp for the windowmaker use pulseaudio, e.g.

$ AlsaMixer.app --device pulse

Here is a two examples where the first one is for ALSA and the other one is for pulseaudio. You can run multiple instances of it. Use the -w option to choose which of the control buttons to bind to the mouse wheel.

# AlsaMixer.app -3 Mic -1 Master -2 PCM --card 0 -w 1
# AlsaMixer.app --device pulse -1 Capture -2 Master -w 2
Note: It can use only those output sinks that set as default.

XMMS2

Make it switch to pulseaudio output

$ nyxmms2 server config output.plugin pulse

and to alsa

$ nyxmms2 server config output.plugin alsa

To make xmms2 use a different output sink, e.g.

 $ nyxmms2 server config pulse.sink alsa_output.pci-0000_04_01.0.analog-stereo.monitor

See also the official guide [3].

KDE Plasma Workspaces and Qt4

PulseAudio will automatically be used by KDE/Qt4 applications. It is supported by default in the KDE sound mixer. For more information see the KDE page in the PulseAudio wiki. One useful tidbit from that page is to add load-module module-device-manager to /etc/pulse/default.pa.

If the phonon-gstreamer backend is used for Phonon, GStreamer should also be configured as described in #GStreamer.

Audacious

Audacious natively supports PulseAudio. In order to use it, set Audacious Preferences -> Audio -> Current output plugin to 'PulseAudio Output Plugin'.

Java/OpenJDK 6

Create a wrapper for the Java executable using padsp as seen on the Java sound with PulseAudio page.

Music Player Daemon (MPD)

configure MPD to use PulseAudio. See also MPD/Tips and Tricks#MPD and PulseAudio.

MPlayer

MPlayer natively supports PulseAudio output with the -ao pulse option. It can also be configured to default to PulseAudio output, in ~/.mplayer/config for per-user, or /etc/mplayer/mplayer.conf for system-wide:

/etc/mplayer/mplayer.conf
ao=pulse

guvcview

guvcview when using the PulseAudio input from a Webcam may have the audio input suspended resulting in no audio being recorded. You can check this by executing:

$ pactl list sources

If the audio source is "suspended" then modifying the following line in /etc/pulse/default.pa and changing:

load-module module-suspend-on-idle

to

#load-module module-suspend-on-idle

And then either restarting PulseAudio or your computer will only idle the input source instead of suspending it. guvcview will then correctly record audio from the device.

Tips and tricks

Keyboard volume control

Map the following commands to your volume keys: XF86AudioRaiseVolume, XF86AudioLowerVolume, XF86AudioMute

First find out which sink corresponds to the audio output you'd like to control. To list available sinks:

pactl list sinks short

Suppose sink 0 is to be used, to raise the volume:

sh -c "pactl set-sink-mute 0 false ; pactl set-sink-volume 0 +5%"

To lower the volume:

sh -c "pactl set-sink-mute 0 false ; pactl -- set-sink-volume 0 -5%"

To mute/unmute the volume:

pactl set-sink-mute 0 toggle

Play sound from a non-interactive shell (systemd service, cron...)

replace foobar with the user running pulseaudio

 machinectl shell .host --uid=foobar /usr/bin/paplay /usr/share/sounds/freedesktop/stereo/complete.oga

X11 Bell Events

To get pulseaudio to handle X11 bell events, uncomment the following two lines in /etc/pulse/default.pa:

load-sample-lazy x11-bell /usr/share/sounds/freedesktop/stereo/bell.oga
load-module module-x11-bell sample=x11-bell

It is impossible to socket activation to handle X11 bell events, so to get them working right after login, start pulseaudio right away using whatever startup implementation your DE supports. There is currently a race condition bug within pulseaudio involving socket activation, so to get pulseaudio starting properly, disable socket activation (see #Running.) To adjust the volume of the X11 bell, do the following:

$ xset b 100

100 is a percentage. This requires the xorg-xset package. This isn't permanent so consider running this command on startup using whatever startup implementation your DE supports.

Troubleshooting

See PulseAudio/Troubleshooting.

See also