USB devices sometimes play back noise or loud and distorted audio
Sometimes USB audio devices will produce noise (presumably either white or pink) which is often highly unpleasant and potentially dangerously loud. It's been encountered by multiple people, though only officially mentioned in #2614 (closed) (but there might be more mentioned somewhere else).
The known:
- noise volume is likely correlated with the PCM volume of the relevant device
- the intended audio signal can often be heard either "over" or "under" the noise
- people reporting this all seem to have either explicitly allowed multiple sample rates or are implicitly using them due to SPA ALSA plugin thinking the HW can't use the one configured rate, so the device gets reconfigured at some point (#2620 (closed))
- the noise can suddenly begin in the middle of a stream that has played without user interruption for for 1-2 minutes
- all reported devices that exhibit this issue have so far been USB devices
- at least at default log level no obvious or corroborating error messages have been observed or reported
- sometimes (possibly due to a HW node reconfigure) the stream and subsequent device node suspend will clear the fault but most often the only solution is to execute
systemctl --user restart pipewire{,-pulse}.socket
- the noise plays even when there is no active client stream until the ALSA HW node itself is closed by PW (and it may resume once the node is re-opened without PW/WP daemon restart)
This is likely a bug in a lower layer such as the driver or even FW/HW itself but perhaps PW can do things differently to avoid triggering it, so it's probably better than not having any official issue at all.
As of early 2023 I'm now mostly getting loud and distorted or maybe clipping audio instead of the noise (in late 2022 it was also modulating the noise). I'll tentatively consider it part of the same issue as the two seem to confound and probably happen together.