[Pkg-utopia-maintainers] Bug#1039012: pipewire-alsa: installing pipewire-alsa:amd64 but not :i386 breaks audio for "plain ALSA" i386 games

[Simon McVittie]

Package: pipewire-alsa
Version: 0.3.71-2
Severity: normal
Control: affects -1 + quake4 etqw

I'm not sure whether this is even fixable, but it seems like something
that should be reported as a known issue, even if it's going to be wontfix.

To reproduce:

* Have i386 as a foreign architecture on an amd64 system
* Use Pipewire for audio (the pipewire-audio metapackage is a good way to
  do this), and in particular, have pipewire-alsa:amd64
* *Don't* have pipewire-alsa:i386
* Use game-data-packager to package the proprietary and non-redistributable
  Quake 4 binaries for i386
* Log in as a user account with which you don't mind running non-auditable
  proprietary binaries
* Run quake4
* Listen for audio

Expected result: audio (for example the intro cinematics include audio).

Actual result: quake4 uses the default output device in the ALSA
user-space API (libasound) for audio. Because pipewire-alsa:amd64 installs
/usr/share/alsa/alsa.conf.d/99-pipewire-default.conf, libasound wants
to use Pipewire; but because I don't have pipewire-alsa:i386, it cannot
load /usr/lib/i386-linux-gnu/alsa-lib/libasound_module_pcm_pipewire.so.
It doesn't fall back to PulseAudio, JACK or "plain ALSA"; instead,
there is no sound output.

Solution from the application side: if the i386 application uses a
typical audio abstraction layer like OpenAL, SDL or Portaudio, then
it will usually work OK. Even if the abstraction layer prefers native
Pipewire over the Pulseaudio protocol, these abstraction layers will
typically try each backend in turn until they find one that works;
so if I have libasound2-plugins:i386 and pipewire-pulse installed, the
abstraction layer will try libasound_module_pcm_pipewire.so, fail to
load it, fall back to libasound_module_pcm_pulse.so, and successfully
connect to pipewire-pulse. (But quake4 doesn't do this: even though it's
a SDL game, it implements its audio by using libasound directly.)

Solution from the user side: if you have pipewire-alsa:amd64 and you
have enabled i386, then you should also install pipewire-alsa:i386. If
#1026780 was implemented in apt, then it could automate this.

    smcv