I have a laptop I've been running Ubuntu 18.04 on for quite a while, and it has a built-in webcam that has historically worked pretty well. I hadn't used the camera for anything for a couple of months, and today when I launched OBS the image initially showed up fine, but after a few seconds became very dark and grainy, as though it had a filter applied. Looks the same in cheese. I've tried rebooting, reloading the uvcvideo module, adjusting settings in guvcview and via several other tools, but it looks the same everywhere and nothing actually fixes it. The only time I see a change at all is when I toggle "Exposure, auto priority" off and back on again - it fades to the normal view, but after a second or two goes dark again.
I can't think of any changes that I've made recently that would have caused this, so I'm guessing something recently updated and messed it up, but thus far trawling the web has not yielded any clues about what that would be or how to fix it. I would appreciate any insight.
lsusb output:
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 005: ID 1e7d:2cee ROCCAT
Bus 001 Device 004: ID 8087:0025 Intel Corp.
Bus 001 Device 006: ID 04f2:b649 Chicony Electronics Co., Ltd
Bus 001 Device 002: ID 0d8c:0005 C-Media Electronics, Inc.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
sudo lsmod | grep video output:
uvcvideo 86016 0
videobuf2_vmalloc 16384 1 uvcvideo
videobuf2_memops 16384 1 videobuf2_vmalloc
videobuf2_v4l2 24576 1 uvcvideo
videobuf2_core 40960 2 videobuf2_v4l2,uvcvideo
videodev 184320 3 videobuf2_core,videobuf2_v4l2,uvcvideo
media 40960 2 videodev,uvcvideo
video 45056 1 i915
EDIT: Immediately after posting this, I moved my laptop to another room and relaunched guvcview... and the problem is gone. I am baffled, since the only thing I did was run the above commands... here's some more output, this time from dmesg | grep video, duplicate messages trimmed for brevity:
[ 3.977130] Linux video capture interface: v2.00
[ 4.028284] uvcvideo: Found UVC 1.00 device Chicony USB2.0 Camera (04f2:b649)
[ 4.032604] uvcvideo 1-4:1.0: Entity type for entity Extension 3 was not initialized!
[ 4.032607] uvcvideo 1-4:1.0: Entity type for entity Processing 2 was not initialized!
[ 4.032608] uvcvideo 1-4:1.0: Entity type for entity Camera 1 was not initialized!
[ 4.032916] usbcore: registered new interface driver uvcvideo
[ 825.512696] uvcvideo: Failed to query (SET_CUR) UVC control 10 on unit 2: -32 (exp. 2).
[ 825.516505] uvcvideo: Failed to query (SET_CUR) UVC control 10 on unit 2: -32 (exp. 2).
...
[ 896.441307] uvcvideo: Failed to query (SET_CUR) UVC control 10 on unit 2: -32 (exp. 2).
[ 896.445849] uvcvideo: Failed to query (SET_CUR) UVC control 10 on unit 2: -32 (exp. 2).
[ 1575.232905] uvcvideo: Failed to resubmit video URB (-19).
[ 1575.236928] uvcvideo: Failed to resubmit video URB (-19).
[ 1575.240902] uvcvideo: Failed to resubmit video URB (-19).
[ 1575.244903] uvcvideo: Failed to resubmit video URB (-19).
[ 1575.248904] uvcvideo: Failed to resubmit video URB (-19).
[ 1612.760969] uvcvideo: Found UVC 1.00 device Chicony USB2.0 Camera (04f2:b649)
[ 1612.765552] uvcvideo 1-4:1.0: Entity type for entity Extension 3 was not initialized!
[ 1612.765558] uvcvideo 1-4:1.0: Entity type for entity Processing 2 was not initialized!
[ 1612.765561] uvcvideo 1-4:1.0: Entity type for entity Camera 1 was not initialized!
[ 2804.103537] uvcvideo: Failed to query (SET_CUR) UVC control 10 on unit 2: -32 (exp. 2).
[ 2804.106589] uvcvideo: Failed to query (SET_CUR) UVC control 10 on unit 2: -32 (exp. 2).
...
[ 3024.013832] uvcvideo: Failed to query (SET_CUR) UVC control 10 on unit 2: -32 (exp. 2).
[ 3086.971099] uvcvideo: Failed to query (SET_CUR) UVC control 10 on unit 2: -32 (exp. 2).
[ 3705.754061] usbcore: deregistering interface driver uvcvideo
[ 3705.842181] uvcvideo: Found UVC 1.00 device Chicony USB2.0 Camera (04f2:b649)
[ 3705.846558] uvcvideo 1-4:1.0: Entity type for entity Extension 3 was not initialized!
[ 3705.846559] uvcvideo 1-4:1.0: Entity type for entity Processing 2 was not initialized!
[ 3705.846560] uvcvideo 1-4:1.0: Entity type for entity Camera 1 was not initialized!
[ 3705.846791] usbcore: registered new interface driver uvcvideo
I remain stumped as to what happened and how to avoid this problem in the future.
