My system logs in journalctl are filled with warning messages regarding the 'gvc_mixer_card'. From google, it seems this has something to do with volume control. I've included a sampling of the messages from the logs below. Where it gets odd is there is nothing playing when these messages are in the log. And, there are no sound issues when something is playing.
Feb 08 10:53:52 Mine gsd-media-keys[1264]: gvc_mixer_card_get_index: assertion 'GVC_IS_MIXER_CARD (card)' failed
Feb 08 10:53:52 Mine gsd-media-keys[1264]: gvc_mixer_card_get_index: assertion 'GVC_IS_MIXER_CARD (card)' failed
Feb 08 10:53:52 Mine gsd-media-keys[1264]: gvc_mixer_card_get_index: assertion 'GVC_IS_MIXER_CARD (card)' failed
Feb 08 10:53:52 Mine gsd-media-keys[1264]: gvc_mixer_card_get_index: assertion 'GVC_IS_MIXER_CARD (card)' failed
Feb 08 10:53:52 Mine gsd-media-keys[1264]: gvc_mixer_card_get_index: assertion 'GVC_IS_MIXER_CARD (card)' failed
Feb 08 10:53:52 Mine gnome-shell[1029]: gvc_mixer_card_get_index: assertion 'GVC_IS_MIXER_CARD (card)' failed
Feb 08 10:53:52 Mine gnome-shell[1029]: gvc_mixer_card_get_index: assertion 'GVC_IS_MIXER_CARD (card)' failed
Feb 08 10:53:52 Mine gnome-shell[1029]: gvc_mixer_card_get_index: assertion 'GVC_IS_MIXER_CARD (card)' failed
Feb 08 10:53:52 Mine gnome-shell[1029]: gvc_mixer_card_get_index: assertion 'GVC_IS_MIXER_CARD (card)' failed
Feb 08 10:53:52 Mine gnome-shell[1029]: gvc_mixer_card_get_index: assertion 'GVC_IS_MIXER_CARD (card)' failed
There are literaly hundreds of these messages per second in the log. They will last for at most 2 seconds. And they repeat sporadically, sometimes 3 or 4 times in an hour, sometimes hours between repeating. They seem to be most common when the machine is idle, but that may be observation bias.
Edit: Some additional info ....
I've noticed that the above messages are always preceded by the message:
Feb 08 15:07:59 Mine gsd-media-keys[1264]: Unable to get default sink
and that line seems to be a result of these lines:
Feb 08 15:07:59 Mine rtkit-daemon[928]: Supervising 5 threads of 3 processes of 1 users.
Feb 08 15:07:59 Mine rtkit-daemon[928]: Successfully made thread 2297655 of process 921 owned by '1000' RT at priority 5.
Feb 08 15:07:59 Mine rtkit-daemon[928]: Supervising 6 threads of 3 processes of 1 users.
The number of threads and processes will vary, but the messages are essentially the same. My first thought was "root kit" but it turned out to be "real-time kit". I was curious about pid's 921 and 928 ...
me@Mine:~$ ps -aux | egrep " 928| 921"
me 921 0.0 0.0 1685400 23872 ? S<sl Jan09 1:06 /usr/bin/pulseaudio --daemonize=no --log-target=journal
rtkit 928 0.0 0.0 154000 1508 ? SNsl Jan09 0:05 /usr/libexec/rtkit-daemon
me 2297845 0.0 0.0 9208 2260 pts/3 S+ 15:21 0:00 grep -E --color=auto 928| 921
Which looks to bring us back to something to do with the audio system. And yet, there are no noticeable issues with sound.
Edit 2: I was wondering if this was possibly an issue with Wayland, so I switched to Xorg.
The error still exists under Xorg. BUT! Instead of repeating the gvc_mixer_card error hundreds of times, it appears only once in the logs. A slight improvement. Still no idea what is causing the error. The audio system continues to function normally.
