go2rtc Troubleshooting

Initial notes

  • make sure your camera is supported by gphoto2 / rpicam-apps / fswebcam
  • make sure your camera is working on Photobooth without setting up go2rtc for preview (if not tested: uninstall go2rtc while running the install-go2rtc-preview.sh script again)
  • make sure you can access http://localhost:1984/api/stream.mjpeg?src=photobooth and having the stream available.

If your camera is supported in general but not having a preview available please check go2rtc for errors. Access go2rtc via http://localhost:1984 and, maybe, adjust the config if needed.

To allow adjustments of the config via web interface adjust the permissions:

sudo chmod 755 /etc/go2rtc.yaml

About the capture wrapper used to capture images

capture is simply a wrapper and accepts exactly the same parameters as gphoto2 / rpicam-apps / fswebcam. The only difference is that the wrapper does the following:

1 Stops Go2rtc

2 executes gphoto2 / rpicam-still / fswebcam with the corresponding parameters.

If only %s is passed, it uses by default the following arguments: - on gphoto2: --set-config output=Off --capture-image-and-download --filename=%s - on rpicam-still: -n -q 100 -o %s - on fswebcam: --no-banner -d /dev/video0 -r 1280x720 %s

Note:: %s gets replaced by Photobooth with the corresponding path and filename.

Run capture --help inside your terminal to get information about the usage of the capture wrapper.

3 Restarts go2rtc

That means: anything that works with the command gphoto2 / rpicam-still / fswebcam will also work with capture, and the word can simply be replaced.

What’s not covered there is a timing issue related to previewing via go2rtc.

Problem Solving: go2rtc Preview via gphoto2

Error: could not claim the USB Device

Another process is using the camera. That's what the log says. Therefore, it can't record.

If you're using gphoto2 this issue is generally addressed inside the troubleshooting for gphoto2, but could also happen because of timing problems.

The preview is created using gphoto2 and streamed by go2rtc. In some rare cases, the preview may not be fully stopped when the capture is triggered. Usually, it's just milliseconds that cause problems. Continue reading on Delay capture to know how to fix possible timing issues.

Delay capture

We can use a tiny pause between stopping the preview and starting the capture to work around this:

sudo wget -O /usr/local/bin/capture https://raw.githubusercontent.com/PhotoboothProject/photobooth/refs/heads/dev/scripts/capture-gphoto2
sudo chmod +x /usr/local/bin/capture

The updated wrapper includes a half-second pause after stopping the preview and before triggering the capture.

Now try again!

Didn’t work? Then continue...

Force the camera to exit Live View

It may be necessary to manually take the camera out of Live View mode. Adjust the capture command (this doesn't work with all cameras!):

capture --set-config movie=0 --trigger-capture --wait-event-and-download=FILEADDED --filename=%s

Now try again!

Didn’t work? Then continue...

More alternative capture commands

capture --trigger-capture --wait-event-and-download=FILEADDED --filename=%s

Or:

capture --wait-event=300ms --capture-image-and-download --filename=%s

For some cameras, this can also noticeably speed up the capture process.

Now try again!

Didn’t work? Then continue...

Set the default go2rtc config correctly

Open http://localhost/admin/captureconfig.php to apply the default suggested configuration automatically.

Then try again.

Capture frame directly from preview

Another alternative, without starting or stopping the preview, is to pull a frame directly from go2rtc.

Open http://localhost/admin/wgetcaptureconfig.php to apply the adjusted configuration.

Then try again.