PulseAudio

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Resources

PulseAudio (or PA for short) is a multi-platform, open source, sound server that provides a number of features on top of the low-level audio interface ALSA, such as:

Networking support (P2P and server mode).
Per-application volume controls.
Better cross-platform support.
Dynamic latency adjustment, which can be used to save power.
Plugin modules.

Installation

Prerequisites

PulseAudio can use but does not need any of:

sys-apps/systemd or
sys-auth/elogind (remember to add elogind -systemd to global USE flag).

Kernel

For motherboards containing HDA sound cards, use the following kernel option for improved power-saving only on machines that are not amd64 or x86 based:

KERNEL

Device Drivers  --->
    <*> Sound card support  --->
        <*> Advanced Linux Sound Architecture  --->
            (2048) Pre-allocated buffer size for HD-audio driver

CONFIG_HIGH_RES_TIMERS is needed to avoid (snd_pcm_recover) underrun errors and degraded audio when some applications are using pulseaudio:

KERNEL

General setup  --->
    Timers subsystem  --->
        [*] High Resolution Timer Support

Note
Not all applications require CONFIG_HIGH_RES_TIMERS to operate properly. However, it is recommended for applications such as media-sound/audacity, and good practice to enable it to ensure compatibility with other audio applications.

See also the permissions section for how to configure the kernel to provide the correct permissions for PA. Also see ALSA's Kernel section for setting the right kernel options for sound card detection.

USE flags

Global

Several packages are aware of the global pulseaudio USE flag to enable support for PulseAudio in other packages. Enabling this USE flag in make.conf will pull in media-sound/pulseaudio automatically (after following the Emerge section):

FILE /etc/portage/make.conf

USE="pulseaudio"

Package

These use flags can be set for the package media-sound/pulseaudio, independently from the global pulseaudio USE flag in make.conf (which configures other packages on the system that can use Pulseaudio):

USE flags for media-sound/pulseaudio A meta package for PulseAudio (networked sound server)

`+glib`	Add support to dev-libs/glib-based mainloop for the libpulse client library, to allow using libpulse on glib-based programs. Build the GSettings PA module.
`bluetooth`	Enable Bluetooth Support
`daemon`	Build the pulseaudio binary (not-needed for pipewire-pulse)
`jack`	Add support for the JACK Audio Connection Kit
`ofono-headset`	Build with oFono HFP backend for bluez 5, requires net-misc/ofono.

Data provided by the Gentoo Package Database · Last update: 2024-09-12 18:37 More information about USE flags

Emerge

After setting USE flags be sure to update the system so the changes take effect:

root #emerge --ask --changed-use --deep @world

Once you have updated your system, you can emerge the PulseAudio package. Begin the installation by using the following command:

root #emerge --ask media-sound/pulseaudio

Additional software

media-sound/pavucontrol - Pulseaudio Volume Control, a GTK based mixer for PulseAudio. Alternatively, media-sound/pavucontrol-qt is the Qt based version.
media-sound/pulsemixer - CLI and curses mixer for PulseAudio
media-sound/paprefs - PulseAudio Preferences, a configuration dialogue for PulseAudio.
KDE's Phonon integrated PulseAudio configuration and mixing, but it is not as powerful as pavucontrol or paprefs.

Configuration

Permissions

Note
This is the only supported configuration by upstream and Gentoo developers.

PulseAudio uses udev to dynamically give access to the soundcards to the currently "active" user.

To make this possible, ACLs (Access Control Lists) are required:

KERNEL

File systems  --->
   Pseudo filesystems  --->
      [*] Tmpfs virtual memory file system support (former shm fs)
      [*]    Tmpfs POSIX Access Control Lists

If a desktop profile is not being used:

for systemd, check that sys-apps/systemd is installed with the acl USE flag enabled
for OpenRC, check that sys-auth/pambase is installed.

When finished, verify the permissions are working correctly:

user $getfacl /dev/snd/controlC0 | grep -Eo "user:.+:" | cut -d: -f2

<YOUR_USERNAME>

Important
For systemd logind managed permissions to be respected, no one may be part of the audio group (not even even the user pulse). Remove any and all users from the audio group:

root #gpasswd -d <user> audio

Configuring other applications

Some applications need to be configured to output to PulseAudio by default. A detailed list of these can be found on the PulseAudio wiki's PerfectSetup page.

ALSA

The media-plugins/alsa-plugins must be installed with the pulseaudio USE flag enabled:

root #emerge --ask media-plugins/alsa-plugins

OSS

Enable the following module in /etc/pulse/default.pa:

FILE /etc/pulse/default.pa

load-module module-oss

GStreamer

Several GConf keys must be set:

Manual with gconftool:

user $

gconftool-2 -t string --set /system/gstreamer/0.10/default/audiosink pulsesink

user $

gconftool-2 -t string --set /system/gstreamer/0.10/default/audiosrc pulsesrc

Note
Some programs might still require GStreamer output plugin to be manually set to PulseAudio Audio Sink.

libao

Set the following in /etc/libao.conf:

FILE /etc/libao.conf

default_driver=pulse

OpenAL

Set the following in /etc/openal/alsoft.conf:

FILE /etc/openal/alsoft.conf

drivers = pulse

MPlayer

Set the following in /etc/mplayer/mplayer.conf:

FILE /etc/mplayer/mplayer.conf

ao=pulse

Without udev or systemd

The information in this section is probably outdated. You can help the Gentoo community by verifying and updating this section.

Warning
Using PulseAudio without udev or systemd is not recommended. This breaks both auto-detection and hot-plugging.

If using ALSA as a PulseAudio sink (output) and routing ALSA apps to PA but not using udev, set a specific device to be used. Otherwise, PulseAudio will use the ALSA device "default" as the sink, which may be routed back to PulseAudio, forming a loop. To avoid this, add the parameter device=hw:0,0 (find the correct IDs by running aplay -l). In the following example, we use two soundcards, of which card 0, device 0 is used as a sink (audio output, e.g. speakers) and card 1, device 0 as a source (audio input, e.g. microphone). PulseAudio will still be able to access other cards than these but it needs these settings to avoid looping the default device in this setup.

FILE /etc/pulse/default.paUsing a specific ALSA device as PulseAudio sink/source

load-module module-alsa-sink device=hw:0,0
load-module module-alsa-source device=hw:1,0

Note
Forgetting to specify this when using the ALSA sink/source modules, problems may only show up on restating PulseAudio (e.g. by logging out and back in or rebooting). There will be with no audio, a slow desktop environment and hanging applications until the loop is resolved, restart alsasound and kill all running pulseaudio processes.

Headless server

The information in this section is probably outdated. You can help the Gentoo community by verifying and updating this section.

These instructions are for setting up a headless pulse audio server. Meaning a server which has no display on it but does have speakers. This provides the ability to use the remote server's speakers for audio output.

There are warnings in good dozen places for doing this, but it is the proper method.

Server

First configure USE flags and emerge the package. The system-wide USE flag is masked, so we have to unmask it.

root #mkdir -p /etc/portage/profile

root #echo "-system-wide" >> /etc/portage/profile/use.mask

root #echo "media-sound/pulseaudio system-wide" >> /etc/portage/package.use

root #emerge --ask --oneshot pulseaudio

Add the following two lines somewhere in the system.pa file:

FILE /etc/pulse/system.pa

load-module module-native-protocol-tcp auth-ip-acl=1.2.3.0/24
load-module module-alsa-sink

Replace 1.2.3.0/24 with the network mask for accessing the server.

Note
With multiple ALSA devices, specify the device to use by adding device or device_id to the module-alsa-sink module

Tell the init script that we really do want to do this, and then start it up:

root #

echo "PULSEAUDIO_SHOULD_NOT_GO_SYSTEMWIDE=1" >> /etc/conf.d/pulseaudio

root #rc-update add pulseaudio default

root #

rc-service pulseaudio start

Client

user $pacmd load-module module-tunnel-sink server=1.2.3.4

server (1.2.3.4) is the IP of the server.

For a more permanent solution, add the following to the default.pa file

FILE /etc/pulse/default.pa

load-module module-tunnel-sink server=1.2.3.4

Now in the pulse audio volume control, there should be the remote server listed under Output Devices. Under playback there should be a button next to the Mute audio button that when clicked will switch that audio stream to whichever output required.

Allow multiple users to use PulseAudio concurrently

In some situations, like software isolation, it may be desirable to run some programs as another users and have access to the PulseAudio daemon. By default, the PulseAudio daemon does not accept connections by secondary users.

The following configuration runs PulseAudio daemon using a UNIX socket that accepts connections from other users.

FILE /etc/pulse/default.pa.d/multi-user.pa

load-module module-native-protocol-unix auth-anonymous=1 socket=/tmp/pulse-socket

FILE /etc/pulse/client.conf

default-server = unix:/tmp/pulse-socket

The above configuration allows different users to access the same sound server. Users do not need to be in the audio, pulse-access or pulse groups. PulseAudio server may need to be executed at startup (see section Running).

Equalizer

Note
The equalizer module is considered unstable and might be removed from pulseaudio. For more, see the mailing list.

Make sure pulseaudio was installed with the equalizer USE flag enabled.

Enabling the required modules

Add the following two lines somewhere in the default.pa file :

FILE /etc/pulse/default.pa

load-module module-dbus-protocol
load-module module-equalizer-sink

Restart the pulseaudio instance. This should be as easy as:

user $pulseaudio -k

user $pulseaudio --start

Choosing the equalizer sink

The command should list the index and name of the equalizer sink:

user $pacmd list-sinks | grep -B1 -e "name:.*equalizer"

Use pavucontrol or a similar program like media-sound/pulsemixer to select the equalizer sink for sound output. It may be listed as a device starting with FFT based equalizer.

Control the equalizer levels

The equalizer levels can now be controlled with the Qt GUI called qpaeq.

Known issues

Short sound events (e.g. the terminal bell) distort ongoing sound streams (e.g. music)

Running

This section contains instructions for starting the PulseAudio daemon.

systemd

To enable PulseAudio for the current user run:

user $systemctl --user enable --now pulseaudio.service pulseaudio.socket

Root can enable PulseAudio for all users:

root #systemctl --global enable pulseaudio.service pulseaudio.socket

OpenRC

Running PulseAudio "systemwide" via an init script is strongly discouraged unless there is good reason to do so. It should instead be started by your desktop session; /etc/xdg/autostart/pulseaudio.desktop is a good place to start.

Manually

The PulseAudio daemon may be launched as a daemon using:

user $pulseaudio -D

For example, if using i3wm:

FILE /home/user/.config/i3/config

exec pulseaudio -D

Troubleshooting

Pulseaudio runtime info can be checked with one command:

user $

pa-info

It prints useful info about all modules loaded and any error can happen while module loading the bootstrap sequence. When there is an issue with PulseAudio, remember to check pa-info output to start troubleshooting.

No sound

After installation: If there is no sound while using ALSA, consider unmuting the sound card. Launch alsamixer and make sure each column has a green 00 under it (use the m key to toggle mute/unmute). Install media-sound/pavucontrol and check if there is any output on the pavucontrol panel when playing audio.
After installation on Intel Tiger Lake-H HD Audio: If there is no sound on Intel Tiger Lake or newer platforms, they may need to load additional firmware file(s). These platforms likely need the sys-firmware/sof-firmware package installed. Then, restart PulseAudio (reboot or relogin to user session).
After upgrading the system: pulseaudio's user configuration files can become corrupt. Deleting ~/.pulse* configuration files and forcing fresh ones to be generated by restarting the daemon may fix no sound condition.

Corrupted audio

Problem: Audio has strange distortion or static when playing an output.

Solution: There is probably an issue with the Pulse server. Kill and restart the server:

user $

pulseaudio --kill

user $

pulseaudio --start

On some very rare occasions, pulseaudio may need reinstalling in case of sound issues:

root #emerge --ask --oneshot pulseaudio

Enable debug mode

To get more information, set the following in /etc/pulse/daemon.conf:

FILE /etc/pulse/daemon.conf

log-level=debug

Afterward restart the daemon:

user $pulseaudio -k

Audio/Video out of sync

Problem: Out-of-sync problems experienced when using PulseAudio over a local network.

Solution: Add tsched=0 to the default.pa file in order to disables time scheduling:

FILE /etc/pulse/default.pa

load-module module-udev-detect tsched=0

Restart the daemon:

user $

pulseaudio --kill

user $

pulseaudio --start

Dummy output

If the only playback device is the Dummy Output, PulseAudio cannot access the system sound devices. Either the user has no permissions (see section Permissions or another program is blocking access. Try:

user $fuser -v /dev/snd/*

It shows the relevant program. Close the program and reconfigure it to use PulseAudio.

No guarantees on actual latencies

Currently PA provides whatever latency is possible at the moment. This can be be milliseconds to hundreds of a millisecond without regard to what applications require.

In case of buffer under-run latencies are never decreased

Currently, if a buffer under-run occurs, PA buffers for longer increasing latency, but it then never tries to buffer for less until restart.

Re-sampling using up a lot of CPU time

Re-sampling can require quite a lot of computational power, PA defaults are rather conservative but in certain cases can still take a significant toll, in such cases edit /etc/pulse/daemon.conf and consider changing resample-method to something less CPU intensive, default-sample-format and default-sample-rate can also affect CPU utilization with higher bit-depth and larger difference in sample-rate generally needing more resources (e.g. re-sampling 44.1 kHz to 48 kHz is faster than re-sampling either to 192 kHz). Since re-sampling is done per each channel per input, channel configuration and number of applications can affect performance as well.

Starting with version 7.0 there is also soxr resamplers made available by enabling the sox USE flag. In particular resample-method = soxr-mq should provide acceptable quality while even the higher quality and hence slower soxr-hq is still cheaper than the default speex-float-1. But be warned that the soxr resamplers have roughly 5-20 times higher latency than speex-float, in terms of time the worst case for soxr-mq/hq can be as high as 20 ms while soxr-vhq latency can in few specific setups reach over 27 ms. In terms of feeling 20 ms can range from unnoticeable to irritating depending on person and use case (the usual PA latency's lower bound is around 20-25 ms and more commonly often around 70-90 ms, for comparison).

Note
Using a version of PA with Orc support can noticeably decrease CPU usage, too. Also PA has the ability, if certain conditions are met, to automatically switch sinks between common sampling rates, this effectively can avoid some re-sampling.

grsec and PulseAudio

Note
Gentoo no longer provides sys-kernel/hardened-sources with the grsecurity patches.^[1]

Make sure the CONFIG_GRKERNSEC_SYSFS_RESTRICT kernel symbol is not enabled when using a grsecurity kernel. PulseAudio’s module-udev-detect needs to access /sys to discover what cards are available on the system, and that kernel option disallows this for anyone but root.

Volume gets randomly louder or reset to 100%

This may be caused by misbehaving PulseAudio-enabled programs when PulseAudio has flat volumes feature enabled. Disable it in the daemon config:

FILE /etc/pulse/daemon.conf

flat-volumes = no

In pavucontrol, unable to change output device for applications that use OpenAL

If changing the output device in pavucontrol has no effect, it could be an application using media-libs/openal, which has a configuration option that inhibits sink changes.

To disable this option, create a configuration file for OpenAL^[2]:

alsoft-config

FILE ~/.config/alsoft.conf

[pulse]
allow-moves=yes

Or, from the GUI, by running :

user $alsoft-config

Popping noises before playing a sound

Pulseaudio hibernates when no sound is played. If you have a popping noise at boot and each time a sound is played, this is due to pulseaudio (re)starting. A workaround is to disable hibernation by creating ~/.config/pulse/default.pa with

FILE ~/.config/pulse/default.pa

.include /etc/pulse/default.pa
.nofail
unload-module module-suspend-on-idle
.fail

External resources

References

↑ https://gitweb.gentoo.org/repo/sync/gentoo.git/tree/metadata/news/2017-08-19-hardened-sources-removal/2017-08-19-hardened-sources-removal.en.txt
↑ John Allie. pavucontrol won't change output on some apps, stackexchange.com questions, July 1, 2018. Retrieved on October 7, 2018.

[1] ttps://gitweb.gentoo.org/repo/sync/gentoo.git/tree/metadata/news/2017-08-19-hardened-sources-removal/2017-08-19-hardened-sources-removal.en.txt

[2] John Allie. pavucontrol won't change output on some apps, stackexchange.com questions, July 1, 2018. Retrieved on October 7, 2018.

[1]

[2]