PipeWire

USE-Flags

Emerge

To emerge PipeWire one can either issue:

or set the screencast USE flag on ebuilds that have it e.g. by adding it to global USE and then rebuilding changed packages:

which should pull in media-video/pipewire as dependency.

Configuration

In order to avoid a lower quality duplicate, PipeWire configuration that is not specific to Gentoo should be found at the project's official wiki instead.

Global PipeWire configuration can be changed by editing /etc/pipewire/pipewire.conf . Additionally PipeWire recognizes multiple environment variables that allow these settings to be changed per-user or individual command. Typically things work reasonably well out of the box, and PipeWire's global configuration is best left alone.

In principle existing PulseAudio or JACK tools can be used to interact with PipeWire when it is set up to behave as a JACK and/or PulseAudio server but currently only parts of the respective APIs have been implemented.

Starting PipeWire with user session

pipewire &

pipewire &

exec --no-startup-id pipewire

Replacing PulseAudio

context.exec = {
    #<program-name> = { [ args = "<arguments>" ] }
    #
    # Execute the given program with arguments.
    #
    # Start the session manager. Run the session manager with -h for
    # options.
    #
    "/usr/bin/pipewire-media-session" = { args = "" }
    #
    # You can optionally start the pulseaudio-server here as well
    # but it better to start it as a systemd service.
    # It can be interesting to start another daemon here that listens
    # on another address with the -a option (eg. -a tcp:4713).
    "/usr/bin/pipewire" = { args = "-c pipewire-pulse.conf" }
}

Replacing JACK

To have JACK clients routed through PipeWire, currently the only method supported by Gentoo is to run them via pw-jack which uses LD_PRELOAD to redirect clients from JACK's original libraries to PipeWire's alternatives:

It should be noted that either due to PipeWire incompleteness or Gentoo configuration shortcomings, not every client will work. Some may even ungracefully exit due to missing symbols. It will likely also require re-configuration of JACK clients, because they will attempt to use their old configuration files, if such exist.

Alternatively it should be possible to have PipeWire connect to a real jackd and act as a gateway for non-JACK applications but, unless there already is a working JACK setup, this is not recommended for the overall worse user experience with JACK.

CS:GO (and other games using the Valve's Source engine)

The default sound buffer length is 0.025. This can sometimes be too low causing cracking audio; for now the workaround is to increase the size of the application's audio buffer from within CS:GO^[1][2]:

snd_mixahead is the length of the sound buffer in seconds, so 0.05 is 50ms (0.10, edited: 25ms is the default). This is essentially the audio delay, so reducing it gives better synchronization. Not all hardware can handle this low of a buffer setting though, so if you hear any crackling or pops at 0.05, increase this setting by 0.01 until the crackling/pops disappear.

Increasing RLIMIT_MEMLOCK for PulseAudio clients (systemd specific)

In case if messages such as this are observed:

one can adjust the amount of memory that pipewire-pulse process can lock via:

and add in the blank space in the upper section of the editor window (not forgetting to save the file afterwards, of course):

...
### Anything between here and the comment below will become the new contents of the file

[Service]
LimitMEMLOCK=256K

### Lines below this comment will be discarded
...

If the system is shared between multiple users, this has to be done for each user (or the created override file has to be copied over with appropriate permissions).

Finally, to have the override applied one must reload the configuration and then restart the service:

The current unit default is set to LimitMEMLOCK=131072 (same as 128K) by the Gentoo package which as of PipeWire 0.3.21 appears to allow for 1 PulseAudio client (subsequent clients will receive buffers backed by unlocked memory). Increasing the number to 256K as seen above should allow for 3 clients with buffers locked to memory at the same time.

While this is just a conjecture, it seems very likely that the LimitMEMLOCK which sets the per-unit hard limit (and implicitly also the LimitMEMLOCKSoft to the same value) must be within the bounds set on the user in question, which is 64 kilobytes for users without realtime capability. To actually have the default 128K or any other value above 64 kilobytes applied, one therefore must set a new limit for non-system accounts:

# This raises the lockable memory upper limit of every process running under a non-system account (except for nobody) from default 64 to 256 kilobytes (in increments of ''page size''); default (soft limit) remains at 64 kilobytes
1000:65533      hard    memlock 256

The new limits are only in effect on new logins, therefore the user must log out and back in. This is usually enough but if pipewire-pulse.service survived the logout, then it must be manually restarted as described previously in this subsection.

Increasing RLIMIT_MEMLOCK for JACK clients (and PulseAudio clients with OpenRC)

Unlike the case of PulseAudio clients, for which the user service does memory locking of buffers, JACK clients do it themselves. In the likely event that the clients report being unable to lock memory, in addition to the hard limit (max permitted value) described in previous sub-section on PulseAudio RLIMIT_MEMLOCK, the soft limit (the default value) must also be raised:

# This both raises the max and sets the default lockable memory limit of every process running under a non-system account (except for nobody) from default 64 to 256 kilobytes (in increments of ''page size'')
1000:65533      -    memlock 256

Bluetooth

By default, Bluetooth support is disabled to avoid clashes with PulseAudio's Bluetooth stack since currently the main use case is as an addition to not a replacement for PA. Uncomment PipeWire's bluez5 module for Bluetooth devices to be listed:

...
modules = {
    ...
    default = [
        ...
        bluez5          # bluetooth support
        ...
    ]
    ...

then run: