Removing PipeWire in Gentoo Linux

PipeWire, all the rage these days, was originally developed for video but was later enhanced to support audio as well, and is now an alternative to PulseAudio and JACK. My laptop running Gentoo Stable (amd64) with the KDE Plasma Desktop had been working fine with PipeWire for some time. The pulseaudio and screencast USE flags were both declared in the file /etc/portage/make.conf. Both audio playback and recording worked fine until a recent upgrade of the packages in my world file, when neither worked any more. The Audio Volume loudspeaker icon (the applet kde-plasma/plasma-pa) on the KDE Plasma panel had a red line through it, and the KMix loudspeaker icon (the applet kde-apps/kmix) on the panel was greyed out. Although I cannot be sure, I suspect the problem started when the first version of PipeWire that supported audio was released. The output of the command ‘ps -ef | grep pulse‘ showed me that both PulseAudio and PipeWire were running. At the time I did not know that PulseAudio is not supposed to be running at the same time as PipeWire. Sometimes when I booted the laptop and logged in, the loudspeaker icons on the Panel would appear correctly and audio output would work properly, but usually this was not the case. This behaviour made me wonder if there was some sort of race condition between the two applications at startup.

Anyway, I stopped PulseAudio being launched automatically at startup. I did this by editing the file /etc/pulse/client.conf to add the line ‘autospawn = no‘ (a comment in the as-installed file indicates that the default value for autospawn is ‘yes‘). That did indeed stop PulseAudio from being launched automatically, and left only PipeWire running. The loudspeaker icons were then displayed correctly on the Panel when I logged in to the KDE Plasma Desktop, and audio output then worked. However, PipeWire did not detect the laptop’s built-in microphone, and no Recording channel was displayed by KMix and Audio Volume. The troubleshooting chapter of the Arch Linux Wiki article on PipeWire has a section suggesting a couple of fixes for this problem (Microphone is not detected by PipeWire) but, even so, I decided to ditch PipeWire and revert to PulseAudio. As much as I dislike PulseAudio (see some of my previous posts on the various problems I have experienced with it), these days it is more or less stable on this laptop and I do not have to mess around too much with audio settings.

A few KDE packages in Gentoo Linux depend on PipeWire (they require the screencast USE flag to be set). I therefore added the following two entries to a file in the directory /etc/portage/package.use/ in order to stop PipeWire being required:

>=sys-apps/xdg-desktop-portal-1.8.1 -screencast
>=kde-apps/krfb-20.12.3 -wayland

I was then able to use the usual command ‘emerge -uvDN @world‘, followed by the command ‘emerge --ask --depclean‘, to rebuild the affected packages and remove PipeWire. I also deleted the line ‘autospawn = no‘ that I had previously added to the file /etc/pulse/client.conf, so that PulseAudio would again be launched automatically at startup. Audio playback and recording are now back to normal. I will probably try PipeWire again in the future but, for the moment, I don’t need it. According to the Gentoo Linux Wiki article on PipeWire:

Warning
As of mid 2021, PipeWire is still in active development and not everything is fully integrated, tested, or implemented – though the project is moving along. While replacing existing audio solutions on Gentoo is possible, the experience is currently not guaranteed to be perfect or free of issues and bugs.

I will therefore wait until the concensus amongst Gentoo Linux users is that PipeWire is trouble-free before I try it again.