Serious playback timing problems affecting GStreamer and other pulseaudio and pipewire audio clients

[Mario Kleiner]

This is a request for a backport of an existing bug fix, present in the recent Pulseaudio version 17 release, to the outdated Pulseaudio 16 releases in jammy - noble.

Affects: Ubuntu 22.04.0 LTS and all later versions.

The fix fixes an annoying start of playback timing bug that affects my own software package octave-psychtoolbox-3 (part of Ubuntu universe), see https://github.com/Psychtoolbox-3/Psychtoolbox-3/issues/814#issuecomment-1723827374 which uses GStreamer for video and audio playback. Psychtoolbox is a very popular toolkit for neuroscience and related medical research, with Ubuntu as the recommended target distribution. It requires high reliability in audio and video presentation timing, so the bug described in the various links below is serious to our users.

The bug also in the same way affects other media applications in Ubuntu which play back audio via the default (auto-plugged) pulseaudiosink GStreamer plugin. See GStreamer bug report https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/1735). The GStreamer bug turned out to be a pulseaudio client library bug (in libpulse.so.0).

Any native pulseaudio client is affected, even if pipewire is used as desktop sound server in recent Ubuntu releases, given that many audio applications still access pipewire via its pulseaudio frontend (package pipewire-pulse). See pipewire bug https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/3399

The bug in libpulse.so.0, reported against Pulseaudio 16 in https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/issues/1383 has been fixed for the Pulseaudio 17 release.

See the following merge request for the following trivial one-liner patch that would need to be backported to Ubuntu's current implementation:

https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/745/diffs

I hoped that Pulseaudio 17 would be included in Debian in time for integration into Ubuntu 24.04-LTS, but apparently not much maintenance of pulseaudio is happening on the Debian side at the moment.

Given that this bug affects all Ubuntu versions since Ubuntu 22.04-LTS, I'd ask kindly for a backport, ideally for Pulseaudio 15.99.1 in 22.04-LTS and Pulseaudio 16.1 in upcoming 24.04-LTS, but at least for the upcoming 24.04-LTS.

Alternatively it would have been great to get Pulseaudio upgraded to version 17 for upcoming Ubuntu 22.04-LTS to fix many more bugs, but apparently that is too late now, according to https://answers.launchpad.net/ubuntu/+source/pulseaudio/+question/709476

Thanks,
-mario

[Mario Kleiner (mario-kleiner)]

Technically this bug belongs to the pulseaudio package in Ubuntu, not pipewire, but the bug tracker does not let me file a bug against pulseaudio.

Ok, managed now to file in the pulseaudio bugtracker under https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/2057684