(Seems like the output of alsa-info is too big so my first message did not go through, I'll use this opportunity to rephrase my original mail somewhat.)
I have Creative Technology Ltd. Live! Cam Chat HD VF0790 (USB ID 041e:4097) and the webcam did work fine with Fedora until a few months ago (likely culprit was the switch from F33 -> F35, which means Pulseaudio -> Pipewire). Since then it records only get garbled sound when I use video calls (actual software does not matter: Firefox, Zoom, ...).
I can reproduce the problem also with /usr/bin/arecord.The problem has something to do with the formats supported by the webcam: S24_3LE and S16_LE.
Whenever I use "S24_3LE" (any bitrate) via "front:CARD=VF0790,DEV=0" (see below) I get a garbled recording. Using the same bitrate via "sysdefault:CARD=VF0790" works fine.
=> My main question is which component creates the "sysdefault"/"front" devices? Are these created by the Linux kernel or maybe pipewire?
$ arecord --list-pcms
sysdefault:CARD=VF0790
Live! Cam Chat HD VF0790, USB Audio
Default Audio Device
front:CARD=VF0790,DEV=0
Live! Cam Chat HD VF0790, USB Audio
Front output / input
Any idea why the "sysdefault" pcm works while "front:" does not?
I naively assumed that both pcms should point to exactly the same device but
there is a diffence.
For good measure here is also the output of alsa-info.sh on my system: https://gist.github.com/FelixSchwarz/9821c437497e198bf0d7711cc0d49eda Thank your very much for reading until here, FelixPS: The same issue exists when using the webcam with Windows 10. However on Windows users can work around the problem by switching the recording from
"2 channel, 24 bit, 48000 Hz" to "2 channel, 16 bit, 48000 Hz".PS(2): There is an alsa kernel quirk for a previous version of the device (VF0770), commit 48827e1d by Jonas Hahnfeld which is meant to fix similar problems. However for that device the solution seems to be to advertise only a single rate with S16_LE. Restricting my camera (VF0790) to S16_LE fixes recording in Firefox (I patched my kernel temporarily to verify this) but does not feel right as arecord was able to use S24_3LE in some cases.
PS(3): When using the "front" PCM with S24_3LE I can not use mono recordings:$ LANG=C arecord --device=front:CARD=VF0790,DEV=0 --file-type wav --format=S24_3LE --channels=1 --rate=8000 --duration=5 test.wav Recording WAVE 'test.wav' : Signed 24 bit Little Endian in 3bytes, Rate 8000 Hz, Mono
arecord: set_params:1358: Channels count non available (this error is the same for any rate)
Attachment:
asound.txt
Description: application/unknown-content-type
Attachment:
arecord-pcms.txt
Description: application/unknown-content-type
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