#### Beyond Linux® From Scratch (systemd Edition) - Version 10.1

### Chapter 42. Multimedia Libraries and Drivers

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# PulseAudio-14.2

## Introduction to PulseAudio

PulseAudio is a sound system for POSIX OSes, meaning that it is a proxy for sound applications. It allows you to do advanced operations on your sound data as it passes between your application and your hardware. Things like transferring the audio to a different machine, changing the sample format or channel count and mixing several sounds into one are easily achieved using a sound server.

This package is known to build and work properly using an LFS-10.1 platform.

### Package Information

- Download (HTTP): https://www.freedesktop.org/software/pulseaudio/releases/pulseaudio-14.2.tar.xz

- Download MD5 sum: 1efc916251910f1e9d4df7810e3e69f8

- Download size: 1.9 MB

- Estimated disk space required: 79 MB (add 1 MB for tests)

- Estimated build time: 0.1 SBU (Using parallelism=4; add 0.3 SBU for tests)

### PulseAudio Dependencies

#### Required

libsndfile-1.0.31

#### Recommended

alsa-lib-1.2.4, dbus-1.12.20, GLib-2.66.7, libcap-2.48 with PAM, Speex-1.2.0 and Xorg Libraries

#### Optional

Avahi-0.8, BlueZ-5.55, fftw-3.3.9, GConf-3.2.6, GTK+-3.24.25, libsamplerate-0.2.1, SBC-1.5 (Bluetooth support), Valgrind-3.16.1, JACK, libasyncns, LIRC, ORC, soxr, TDB, and WebRTC AudioProcessing

User Notes: http://wiki.linuxfromscratch.org/blfs/wiki/pulseaudio

## Installation of PulseAudio

Install PulseAudio by running the following commands:

    mkdir build &&
    cd    build &&

    meson  --prefix=/usr -Ddatabase=gdbm -Dbluez5=false &&
    ninja

To test the results, issue: ninja test. One test fails if the tests are not run as the root user, but this can be ignored.

Now, as the `root` user:

    ninja install

Running PulseAudio as a system-wide daemon is possible but not recommended. See https://www.freedesktop.org/wiki/Software/PulseAudio/Documentation/User/SystemWide/ for more information. While still as the `root` user, remove the D-Bus configuration file for the system wide daemon to avoid creating unnecessary system users and groups:

    rm -fv /etc/dbus-1/system.d/pulseaudio-system.conf

## Command Explanations

`-Dbluez5=false`: This switch prevents a runtime error if dbus-1.12.20 and SBC-1.5 are both installed but BlueZ-5.55 is not installed. Remove this if you have installed all three packages.

## Configuring PulseAudio

###

#### Config Files

There are system wide configuration files: `/etc/pulse/daemon.conf`, `/etc/pulse/client.conf`, `/etc/pulse/default.pa`, and user configuration files with the same names in `~/.config/pulse`. User configuration files take precedence over system wide ones.

###

#### Configuration Information

You may have to configure the audio system. You can start pulseaudio in command line mode using pulseaudio -C and then list various information and change settings. See man pulse-cli-syntax.

If pulseaudio was working but you no-longer have sound, after checking for hardware issues (speakers or headphones not connected, external amplifier not connected) you may need to fix it.

One suggestion is to close the application, such as firefox where sound has stopped working, then run: pactl list short sinks followed by: pacmd set-default-sink <sink #> and then restart the application.

If that does not work, a more drastic approach often works. After closing the application, close pulseaudio, either using pulseaudio --kill or, if that fails, killall -KILL pulseaudio and then rm -rf ~/.config/pulse/* (and perhaps also rm -rf ~/.pulse/* if you have used a very old version of pulse on this machine), then run pulseaudio --verbose to restart it. If the daemon starts, restart the application. See man pulseaudio for more options.

## Contents

Installed Programs: pacat, pacmd, pactl, padsp, pamon (symlink to pacat), paplay (symlink to pacat), parec (symlink to pacat), parecord (symlink to pacat), qpaeq, pasuspender, pax11publish, pulseaudio, and start-pulseaudio-x11
Installed Libraries: libpulse.so, libpulse-mainloop-glib.so, libpulse-simple.so, libpulsecommon-14.2.so, libpulsecore-14.2.so, and libpulsedsp.so
Installed Directories: /etc/pulse, /usr/include/pulse, /usr/lib/cmake/PulseAudio, /usr/lib/{pulseaudio,pulse-14.2}, /usr/libexec/pulse, and /usr/share/pulseaudio

### Short Descriptions

pacat | plays back or records raw or encoded audio streams on a PulseAudio sound server
pacmd | is a tool used to reconfigure a PulseAudio sound server during runtime
pactl | is used to control a running PulseAudio sound server
padsp | is the PulseAudio OSS Wrapper
pamon | is a symbolic link to pacat
paplay | is used to play audio files on a PulseAudio sound server
parec | is a symbolic link to pacat
parecord | is a symbolic link to pacat
pasuspender | is a tool that can be used to tell a local PulseAudio sound server to temporarily suspend access to the audio devices, to allow other applications to access them directly
pax11publish | is the PulseAudio X11 Credential Utility
pa-info | is a shell script that prints various information relating to the Pulseaudio server currently in use
pulseaudio | is a networked low-latency sound server for Linux
qpaeq | is an equalizer interface for PulseAudio equalizer sinks (Requires fftw-3.3.9 at build time)
start-pulseaudio-x11 | starts PulseAudio and registers it to the X11 session manager

Last updated on 2021-02-21 15:09:04 -0800

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