The punktfunk/1 virtual microphone was created as a plain Audio/Source with
no session priority, which caused two failures — both diagnosed live against a
Bazzite host on PipeWire 1.4.10:
1. It was never WirePlumber's default source, so any app recording the *default*
input (games, Discord, arecord) heard silence. This is the Linux analogue of
the Windows host forcing the default recording endpoint (audio_control.rs).
2. The real killer on PipeWire 1.4.x: a *non-default* Audio/Source recorded via
`--target` never gets a driver assigned — the {source, recorder} group stays
orphaned (pw-top QUANT/RATE 0, driver-node None), so the RT process() callback
never fires and even an explicitly-selected mic is pure silence. PipeWire 1.6
drives any recorded source regardless, which is why the host worked on a 1.6
box but not the 1.4.10 Bazzite host.
Fix: advertise a high priority.session on the source so WirePlumber elects it as
the default source and keeps it driven. Reproduced with a faithful standalone
copy of the node on the same 1.4.10 daemon: no priority.session -> silent,
priority.session set -> audio. Only overrides WirePlumber's auto default; a
user's explicit default.configured.audio.source still wins.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
enricobuehler
df21b54cd0