error with v4l2ctl focus settings (Logitech C920)

[dmnkhhn]

What happened

If I use the examples from the manual to control my Logitech C920 Camera I get this:

pi@voron2:~ $ v4l2-ctl -d /dev/video0 -c focus_auto=0
unknown control 'focus_auto'
pi@voron2:~ $ v4l2-ctl -d /dev/video0 -c focus_absolute=30
VIDIOC_S_EXT_CTRLS: failed: Input/output error
focus_absolute: Input/output error

With this line in my config I get this output in the log:

[03/09/23 12:00:48] crowsnest: V4L2 Control: Device: [cam 1]
[03/09/23 12:00:48] crowsnest: V4L2 Control: Options: focus_auto=0,focus_absolute=30
[03/09/23 12:00:48] crowsnest: V4L2 Control: Failed to set parameter: 'focus_auto=0' ...
[03/09/23 12:00:48] crowsnest: V4L2 Control: Failed to set parameter: 'focus_absolute=30' ...
[03/09/23 12:00:49] crowsnest: Try to start configured Cams / Services...
[03/09/23 12:00:50] crowsnest: INFO: Configuration of Section [cam 1] looks good. Continue...
[03/09/23 12:00:52] crowsnest: ... Done!
[03/09/23 12:00:52] crowsnest: Starting ustreamer with Device /dev/video0 ...
[03/09/23 12:00:53] crowsnest: WARN: Detected 'brokenfocus' device.
[03/09/23 12:00:53] crowsnest: INFO: Trying to set to configured Value.
[03/09/23 12:00:53] crowsnest: ERROR: Error 255 occured on line 114
[03/09/23 12:00:53] crowsnest: ERROR: Stopping crowsnest.
[03/09/23 12:00:53] crowsnest: Goodbye...

Maybe a firmware update changed those parameters?! The (newly?) available controls are:

pi@voron2:~ $ v4l2-ctl -d /dev/video0 --list-ctrls

User Controls

                     brightness 0x00980900 (int)    : min=0 max=255 step=1 default=128 value=128
                       contrast 0x00980901 (int)    : min=0 max=255 step=1 default=128 value=128
                     saturation 0x00980902 (int)    : min=0 max=255 step=1 default=128 value=128
        white_balance_automatic 0x0098090c (bool)   : default=1 value=1
                           gain 0x00980913 (int)    : min=0 max=255 step=1 default=0 value=0
           power_line_frequency 0x00980918 (menu)   : min=0 max=2 default=2 value=2
      white_balance_temperature 0x0098091a (int)    : min=2800 max=7500 step=1 default=5000 value=4472 flags=inactive
                      sharpness 0x0098091b (int)    : min=0 max=255 step=1 default=128 value=128
         backlight_compensation 0x0098091c (int)    : min=0 max=1 step=1 default=0 value=0

Camera Controls

                  auto_exposure 0x009a0901 (menu)   : min=0 max=3 default=3 value=3
         exposure_time_absolute 0x009a0902 (int)    : min=3 max=2047 step=1 default=156 value=156 flags=inactive
     exposure_dynamic_framerate 0x009a0903 (bool)   : default=0 value=1
                   pan_absolute 0x009a0908 (int)    : min=-36000 max=36000 step=3600 default=0 value=0
                  tilt_absolute 0x009a0909 (int)    : min=-36000 max=36000 step=3600 default=0 value=0
                 focus_absolute 0x009a090a (int)    : min=0 max=250 step=1 default=0 value=59
     focus_automatic_continuous 0x009a090c (bool)   : default=1 value=0
                  zoom_absolute 0x009a090d (int)    : min=100 max=500 step=1 default=100 value=100

If I update my configuration and set v4l2ctl: focus_automatic_continuous=0,focus_absolute=30, which works when setting it manually from the command line, the following appears in my log:

[03/09/23 11:50:50] crowsnest: INFO: Configuration of Section [cam 1] looks good. Continue...
[03/09/23 11:50:52] crowsnest: ... Done!
[03/09/23 11:50:52] crowsnest: Starting ustreamer with Device /dev/video0 ...
[03/09/23 11:50:53] crowsnest: WARN: Detected 'brokenfocus' device.
[03/09/23 11:50:53] crowsnest: INFO: Trying to set to configured Value.
[03/09/23 11:50:54] crowsnest: ERROR: Error 255 occured on line 114
[03/09/23 11:50:54] crowsnest: ERROR: Stopping crowsnest.
[03/09/23 11:50:54] crowsnest: Goodbye...

Now crowsnest will start again, but it gets the same error and it goes on repeat and after a short while the Pi is almost overheating.

TL;DR
As soon as I set the focus parameter (new or old) the brokenfocus device warning comes up and crowsnest continuously restarts.

What did you expect to happen

I would expect the v4l2ctl setting to work properly with the updated parameters for my Logitech C920

How to reproduce

• connect the camera via USB
• get the available parameters v4l2-ctl -d /dev/video0 --list-ctrls
• set the focus_automatic_continuous parameter to 0
• set the focus_absolute parameter to something between 0 and 250
• check the log

Additionally you could set those parameters from the command line to see if they work at all:
v4l2-ctl -d /dev/video0 -c focus_automatic_continuous=0
v4l2-ctl -d /dev/video0 -c focus_absolute=125

Additional information

crowsnest: Version: v3.0.7-3-g20ed6a8
crowsnest: Host Info: Distribution: Raspbian GNU/Linux 11 (bullseye)
crowsnest: Host Info: Kernel: Linux 6.1.14-v7+ armv7l
crowsnest: Host Info: Model: Raspberry Pi 3 Model B Plus Rev 1.3
crowsnest: Version Control: ustreamer is up to date. (v4.13)
crowsnest: Version Control: rtsp-simple-server is up to date. (v0.20.2)
crowsnest: Version Control: ffmpeg is up to date. (4.3.5-0+deb11u1+rpt3)

[KwadFan]

Hey there,

First of all, as I do not own this camera it is hard to reproduce for me, which makes it impossible to fix.

But...

[03/09/23 12:00:48] crowsnest: V4L2 Control: Failed to set parameter: 'focus_auto=0' ...
[03/09/23 12:00:48] crowsnest: V4L2 Control: Failed to set parameter: 'focus_absolute=30' ...

these to lines already tell you what is going on here.

These Logitech Cams (C920, C922, C930e) are known to have issues in firmware and there where several tries fron linux kernel devs to workaround those issues.

The camera simply refuses to set those parameters at runtime. Currently those parameters are set before ustreamer starts, and the "brokenfocus" fix already tries to re-set those values after ustreamer is started. But if the camera wont let you set these values, for what ever reason, it fails which is intended.

So its hard to say but I cant help you here, simply because I need the exact same model and firmware of your cam to reproduce and develop a workaround.

Maybe @zellneralex has an idea here.
Regards Kwad

[zellneralex]

No I have no other idea. We would need to have that cam to do further investigations.

@KwadFan is v4l2ctl: focus_automatic_continuous=0,focus_absolute=30 maybe the problem here.
Would we see more if he uses the debug option?

[KwadFan]

So,
the only thing we can do is a bit a guessing game here.

@dmnkhhn
Please set log_level: debug and delete_log: true. Restart crowsnest and upload the complete new log.

[time-tm]

I have the same C920. Had the exact same issue. Changing focus_auto=0 to focus_automatic_continuous=0 solved it for me.

[TheHipsterGandalf]

I have the same C920. Had the exact same issue. Changing focus_auto = 0 to focus_automatic_continuous = 0 solved it for me.

Thank you for this, it has solved my problem!

[Imburr]

This also fixed it for me, thank you. For the next person here, there is no spacing in the config file, i.e.

v4l2ctl: focus_automatic_continuous=0,focus_absolute=20

Also interesting, I have been running 2 of these cameras for 12+ months without issue, something changed recently to have caused this to begin crashing.

[zao]

My experience with the C920 camera is that the firmware in the camera refuses to set the exposure and focus values if the corresponding feature is configured to be automatic. This includes the case where one command line tries to change those features from auto to manual mode and adjust the value at the same time.

Results can vary over time in a session if you've managed to change the mode beforehand after which the value setting is likely to take.

Before moving to Klipper+crowsnest I had to run two distinct commands in rc.local, one to first configure the mode toggles followed by one to actually adjust the manual values:

v4l2-ctl --set-ctrl=auto_exposure=1,focus_automatic_continuous=0,white_balance_automatic=0,power_line_frequency=1
v4l2-ctl --set-ctrl=exposure_time_absolute=200,focus_absolute=40,white_balance_temperature=4395

I can't find any way in crowsnest.conf to do this kind of "two-phase" control setting. I could probably work around it by writing a janky v4l2-ctl wrapper that splits a command line into two based on the types of arguments but it'd be nice to have some sort of upstream support for this kind of horror.

One interesting side note is that the focus_auto parameter mentioned earlier in the issue is called focus_automatic_continuous on my model.

  idVendor           0x046d Logitech, Inc.
  idProduct          0x082d HD Pro Webcam C920
  bcdDevice            0.11

[behold81]

focus_automatic_continuous=0

V4L2 Control: Parameter 'focus_automatic_continuous=0' not available for '/dev/video0'. Skipped.

Not an option for me

[behold81]

My experience with the C920 camera is that the firmware in the camera refuses to set the exposure and focus values if the corresponding feature is configured to be automatic. This includes the case where one command line tries to change those features from auto to manual mode and adjust the value at the same time.

Results can vary over time in a session if you've managed to change the mode beforehand after which the value setting is likely to take.

Before moving to Klipper+crowsnest I had to run two distinct commands in rc.local, one to first configure the mode toggles followed by one to actually adjust the manual values:

v4l2-ctl --set-ctrl=auto_exposure=1,focus_automatic_continuous=0,white_balance_automatic=0,power_line_frequency=1
v4l2-ctl --set-ctrl=exposure_time_absolute=200,focus_absolute=40,white_balance_temperature=4395

I can't find any way in crowsnest.conf to do this kind of "two-phase" control setting. I could probably work around it by writing a janky v4l2-ctl wrapper that splits a command line into two based on the types of arguments but it'd be nice to have some sort of upstream support for this kind of horror.

One interesting side note is that the focus_auto parameter mentioned earlier in the issue is called focus_automatic_continuous on my model.

  idVendor           0x046d Logitech, Inc.
  idProduct          0x082d HD Pro Webcam C920
  bcdDevice            0.11

it seems to fail to apply when done to quickly. it works perfectly when edited in the shell. and never falters till I restart the Pi

[KwadFan]

focus_automatic_continuous=0

V4L2 Control: Parameter 'focus_automatic_continuous=0' not available for '/dev/video0'. Skipped.

Not an option for me

There is no "option" if v4l2-ctl does not list that parameter for your device /dev/video0 you simply cant use it, and thats what this line tells you. Not more not less...

crowsnest/libs/v4l2_control.sh

Line 47 in 20ed6a8

if [[ "${opt_avail}" -eq "0" ]]; then

[KwadFan]

My experience with the C920 camera is that the firmware in the camera refuses to set the exposure and focus values if the corresponding feature is configured to be automatic. This includes the case where one command line tries to change those features from auto to manual mode and adjust the value at the same time.

Results can vary over time in a session if you've managed to change the mode beforehand after which the value setting is likely to take.

Before moving to Klipper+crowsnest I had to run two distinct commands in rc.local, one to first configure the mode toggles followed by one to actually adjust the manual values:

v4l2-ctl --set-ctrl=auto_exposure=1,focus_automatic_continuous=0,white_balance_automatic=0,power_line_frequency=1
v4l2-ctl --set-ctrl=exposure_time_absolute=200,focus_absolute=40,white_balance_temperature=4395

I can't find any way in crowsnest.conf to do this kind of "two-phase" control setting. I could probably work around it by writing a janky v4l2-ctl wrapper that splits a command line into two based on the types of arguments but it'd be nice to have some sort of upstream support for this kind of horror.

One interesting side note is that the focus_auto parameter mentioned earlier in the issue is called focus_automatic_continuous on my model.

  idVendor           0x046d Logitech, Inc.
  idProduct          0x082d HD Pro Webcam C920
  bcdDevice            0.11

As you can see here

crowsnest/libs/v4l2_control.sh

Line 41 in 20ed6a8

for param in "${opt[@]}"; do

It sets the values in a for loop, so each paramater after another. You could try to add a sleep state but it will delay its startup anyways. So, there is not much I can do if the Firmware is simply to slow to except settings in a small time frame. Besides, that for all users that are not affected by it have to wait even unnecessary longer to come up.

I cant test changes because I do not own any Logitech Cams. So feel free to add a PR with a fix.
It has to be done in the develop branch wich changes its behavio completly, because if you are using camera-streamer as backend its no longer done via v4l2-ctl, its handled by start parameters of camera-streamer. Therefor no possibilty to delay that commands.

[Sidkrsk]

None of the above methods of solving this problem helped me, so I went ahead and found a way in which they add a file to the directory /etc/udev/rules.d/99-video-c920.rules, but the configurations described there also did not apply. I searched again and found this archlinux I checked the device id and replaced it with the necessary parameters and hooray, everything worked for me! I hope this method will help someone)

[chrishoage]

I have the same C920. Had the exact same issue. Changing focus_auto = 0 to focus_automatic_continuous = 0 solved it for me.

For anyone coming from google this may not be just a C920 issue. I have a C615 and had the exact same issue, along with the same solution.

This started happening after a dist-upgrade on the klipper host - so I'm guessing either the v4l2 binary changed or the driver interface.

In any case - wanted to share that this solution may work for other Logitech cameras