PulseAudio

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, either systemd or sys-auth/elogind. If using the latter, remember to add elogind and -systemd as global USE flags.

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.

Device Drivers --->
 <*> Sound card support Search for <code>CONFIG_SOUND</code> to find this item. --->
 <*> Advanced Linux Sound Architecture Search for <code>CONFIG_SND</code> to find this item.

Refer to the "Kernel" section of the "ALSA" page for setting the right kernel options for sound card detection.

PulseAudio uses udev to dynamically give the currently 'active' user access to the soundcard(s). To make this possible, ACLs (Access Control Lists) are required.

File systems --->
 Pseudo filesystems --->
 [*] Tmpfs virtual memory file system support (former shm fs) Search for <code>CONFIG_TMPFS</code> to find this item.
 [*] Tmpfs POSIX Access Control Lists Search for <code>CONFIG_TMPFS_POSIX_ACL</code> to find this item.

CONFIG_HIGH_RES_TIMERS is needed to avoid (snd_pcm_recover) underrun errors and degraded audio when some applications are using PulseAudio. Not all applications require CONFIG_HIGH_RES_TIMERS to operate properly; however, it is recommended for applications such as Audacity, and good practice to enable it to ensure compatibility with other audio applications.

General setup --->
 Timers subsystem --->
 [*] High Resolution Timer Support Search for <code>CONFIG_HIGH_RES_TIMERS</code> to find this item.

USE flags

The global pulseaudio USE flag enables support for PulseAudio in packages. Enabling it in make.conf will cause media-libs/libpulse to be installed when emerging such packages.

The USE flags for libpulse itself are:

The USE flags for the media-sound/pulseaudio-daemon package are:

Emerge

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

Once the system has been updated, the libpulse and pulseaudio-daemon packages can be installed:

Additional software

• media-sound/pavucontrol - Pulseaudio Volume Control, a GTK mixer. media-sound/pavucontrol-qt is the Qt version.
• media-sound/pulsemixer - TUI mixer.
• media-sound/paprefs - PulseAudio Preferences, a GTK-based configuration UI.
• kde-plasma/plasma-pa - KDE Plasma applet integrating configuration and mixing, but not as powerful as pavucontrol or paprefs.

Configuration

Permissions

If a desktop profile is not being used:

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

Then, verify the permissions are working correctly:

This should output the name of the user using PulseAudio.

Files

• /etc/pulse/default.pa - daemon startup file. Refer to default.pa(5) .
• $HOME/.config/pulse/default.pa - user-specific version of /etc/pulse/default.pa.
• /etc/pulse/system.pa - daemon startup file for system-wide setups.
• /etc/pulse/client.conf - client configuration file. Refer to pulse-client.conf(5) .
• $HOME/.config/pulse/client.conf - user-specific version of /etc/pulse/client.conf.

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:

OSS

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

load-module module-oss

GStreamer

Several GConf keys must be set:

• Manual with gconftool:

libao

Set the following in /etc/libao.conf:

default_driver=pulse

OpenAL

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

drivers = pulse

MPlayer

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

ao=pulse

Without udev or systemd

If using ALSA as a PulseAudio sink (output) and routing ALSA apps to PulseAudio but not using udev, the device to use must be specified. 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 to /etc/pulse/default.pa, where 0,0 should be replaced by the appropriate values as found in the output of aplay -l. Without this, 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. Once the configuration is updated, restart alsasound and kill all running PulseAudio processes.

In the following example, there are two soundcards specified: card 0, device 0 is used as a sink (audio output, e.g. speakers), and card 1, device 0 is used as a source (audio input, e.g. microphone). PulseAudio will still be able to access other cards.

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

Headless server

A headless PulseAudio server is a server which has no display attached to it but does have speakers. This provides the ability to use the remote server's speakers for audio output.

Server

Then re-emerge pulseaudio-daemon:

Next, add the following two lines somewhere in the /etc/pulse/system.pa file:

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

where x.x.x.x/24 should be replaced by the network mask for accessing the server.

Finally, on OpenRC systems, configure the pulseaudio service to confirm the required setup, and start the service:

Client

server (x.x.x.x) is the IP of the server.

where x.x.x.x should be replaced by the IP address of the server.

For a more permanent solution, add the following to the /etc/pulse/default.pa file:

load-module module-tunnel-sink server=x.x.x.x

where x.x.x.x should again be replaced by the IP address of the server.

When setup is complete, pavucontrol should list the remote server listed under "Output Devices", and under "Playback" there should be a button next to the "Mute audio" button which, when selected, will switch that audio stream to whichever output is required.

Multiple concurrent users

By default, the PulseAudio daemon doesn't accept connections from secondary users. However, in some situations, like software isolation, it may be desirable for a user to run programs as some other user and still have access to the PulseAudio daemon.

In this situation, configure PulseAudio to use a UNIX domain socket that accepts connections from secondary users:

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

Then configure the PulseAudio client library to use this socket:

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

This configuration does not need users to be in the audio, pulse-access, or pulse groups.

Equalizer

To enable the equalizer, build media-sound/pulseaudio-daemon with the equalizer USE flag enabled. This also requires that the dbus USE flag be enabled.

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

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

Usage

Starting the daemon

systemd

To enable PulseAudio for the current user run:

Root can enable PulseAudio for all users:

OpenRC

Running PulseAudio "system-wide" via the pulseaudio OpenRC system service is strongly discouraged unless there is good reason to do so.

The standard way of starting the PulseAudio daemon is autospawning^[1] , in which D-Bus is used to request that the daemon be started. On non-systemd systems, the media-sound/pulseaudio-daemon package will install the file enable-autospawn.conf to enable autospawning.

The pulseaudio.desktop file calls the start-pulseaudio-x11 script, which configures PulseAudio for running under X.

Manually

To start a PulseAudio daemon:

Equalizer

To list the index and name of the equalizer sink:

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

Equalizer levels can be controlled with media-sound/qpaeq , a Qt GUI.

Troubleshooting

Refer to PulseAudio/troubleshooting.

See also

• ALSA — the Linux kernel's API for sound cards, together with an associated software framework
• PipeWire — low-latency, graph-based, processing engine and server, for interfacing with audio and video devices.

External resources

Official documentation

• Running PulseAudio
• PulseAudio: The Perfect Setup
• PulseAudio Frequently Asked Questions
• pulseaudio(1)
• pulse-daemon.conf(5)
• default.pa(5)
• pacmd(1)

Other information

• Getting DTS 5.1+ sound via S/PDIF or HDMI using PulseAudio
• More general troubleshooting tips
• Why you should care about PulseAudio (and how to start doing it)

References

• Outdated articles
• Audio
• Multimedia
• Daemons