WalkThrough_User_PulseOnJack

What Is PulseAudio?

PulseAudio is a sound server for POSIX and Win32 systems. A sound server is basically a proxy for your 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.

See http://pulseaudio.org/.

Running PulseAudio on top of JACK

If you intend to use consumer applications like Flash or media players in your JACK setup, one possible solution is to use PulseAudio as an intermediate layer for all these non-JACKified programs. Basically, it boils down to the following:

1. Redirect all ALSA output to PulseAudio
2. Redirect PulseAudio to JACK

A: with JACK2 and jackdbus

a) Install Cadence

The clicky GUI method, no hackery required: Install Cadence from the KXStudio repositories. From within Cadence you can enable the ALSA and PulseAudio bridges with the GUI. Done.

b) Using scripts in QJackCtl

The nerdy, elegant and powerful method, slightly more setup required: QJackCtl can launch scripts. This is extremely powerful and you can let it do all the magic for you. A ready made script can be found at brummer10

B: with JACK1

Warning 1: If you follow this setup there is no control with QJackCtl. Any settings there will have no effect. You will have to make changes to the configuration with jack_control. jack_control has no man page, try jack_control --help.

Warning 2: After the computer's wake from suspend you will have to restart PulseAudio and possibly the application using it. (If it is a browser plugin using the audio (flash), reloading the page should suffice. If it is html5 audio you will have to restart the browser) However, be aware that doing so might freeze programs connecting to Jack directly.

pulseaudio -k

Warning 3: It has been said about this method that it is "the hardest way to do it [PulseAudio on JACK]". It probably needs a rewrite. Proceed with care.

Redirecting ALSA to PulseAudio

Use the following settings in /etc/asound.conf (or $HOME/.asoundrc)

pcm.pulse {
    type pulse
}

ctl.pulse {
    type pulse
}

pcm.!default {
    type pulse
}
ctl.!default {
    type pulse
}

Redirecting PulseAudio to JACK

On Debian-like systems, be sure to install pulseaudio-module-jack. (TODO: Add information about Fedora, OpenSuSE and the lot)

Then, use the following configuration if you intend to run jackd all the time:

~/.config/pulse/default.pa:

load-module module-native-protocol-unix
load-module module-jack-sink channels=2
load-module module-jack-source channels=2
load-module module-null-sink
load-module module-stream-restore
load-module module-rescue-streams
load-module module-always-sink
load-module module-suspend-on-idle
set-default-sink jack_out
set-default-source jack_in

The following isn't strictly necessary but might be useful. ~/.config/pulse/daemon.conf:

default-sample-format = float32le
default-sample-rate = 48000
realtime-scheduling = yes
exit-idle-time = -1

If you're using qjackctl as a launcher for jackd.

in settings options add a post startup script like this:

pactl load-module module-jack-sink channels=2; pactl load-module module-jack-source channels=2; pacmd set-default-sink jack_out