fix: avoid crash on mute with vlc pipewire audio output

[slurpeestraw]

On Fedora (and anywhere else vlc-plugin-pipewire is installed), VLC processes can die with SIGSEGV when a video is muted or its volume is changed. Every player is muted as soon as it is created (PlayerBase.init_player), so this can hit on startup.

Cause

The crash is in the PipeWire audio output plugin:

#0 MuteSet ()                  libaout_pipewire_plugin.so
#1 aout_OutputUnlock ()        libvlccore.so.9
#2 aout_MuteSet ()             libvlccore.so.9
#3 libvlc_audio_set_mute ()    libvlc.so.5

The plugin's Open() allocates its private struct with malloc and never sets sys->stream. Only Start() (on the first audio frame) and Stop() write it. MuteSet() and VolumeSet() check if (sys->stream != NULL) and dereference it. So a mute or volume change before the first audio plays follows whatever the allocator left there.

Waiting for "playing" before muting doesn't help. The output starts on the decoder thread, after that event, and a video without audio never starts it at all.

Seen with vlc-3.0.23-1.fc43, vlc-plugin-pipewire-3-6.fc43, pipewire-1.4.11.

Fix

On Linux, ask VLC for --aout=pulse,any. On PipeWire desktops pulse is served by pipewire-pulse; on systems without a pulse server, ,any falls back to whatever VLC would have picked. It goes before the options typed by hand in settings, so a user's own --aout still wins. The AppImage's existing --aout=pulse is unchanged.

Reproduction

from gridplayer.vlc_player.libvlc import vlc

mp = vlc.Instance(["--quiet", "--no-video"]).media_player_new()
mp.audio_set_mute(True)

On Fedora 43 this segfaults on every run (5/5). With --aout=pulse,any it exits cleanly (5/5), and the PipeWire plugin is never loaded.

Testing

• New tests/test_vlc_audio_output.py: pulse is asked for on Linux, a hand-typed --aout still wins, and other platforms are left alone.
• pytest on Python 3.14: everything passes except 5 tests that also fail on master in my environment (text eliding in the overlay tests, and test_ytdl_js_runtimes picking up a container's /run/host). Not run on 3.10 locally.
• ruff check, ruff format --check, rumdl check and pre-commit pass.

[vzhd1701]

Thank you very much!