Snapshot black when not streaming on USB Device

[cavernerg]

I use a logitech USB Cam to monitor my 3D printer. When I grab a snapshot (via Octoslack/Octoprint) I get a black image, if nothing else needs the cam. If I stream while Octosclack downloads the snapshot, it's fine.

[AlexxIT]

Please provide more info. How you setup stream.

[cavernerg]

Thanks for replying. Here is an example picture

This is the entry in config file:
ffmpeg:device?video=1#video=mjpeg#hardware

[AlexxIT]

Show what you can see WebUI > Add > USB

[cavernerg]

it is a Logitech C615 Camera. To me it seems like the camera is in standby and when go2rtc takes the snapshot, the camera is not fully awake and adjusted to the light.
Because if I am watching the stream on my android and go2rtc takes the snapshot in the same moment, everything is fine.

The light dots in the example picture in the post 3 days ago are from the LED-Strip, which permanently lights up the 3D-Printer

[AlexxIT]

Use config as suggested in WebUI. You don't need transcoding for mjpeg, because camera support this format out of box.

[cavernerg]

Oh right, I was there before and tried around - but the result remains the same.

[AlexxIT]

What about stream? Do you have problems only with snapshots?

[cavernerg]

Stream works flawless. Only snapshots are problematic. And that only, when camera is not in use e.g. through parallel streaming.

[AlexxIT]

Have you tried to get snapshot during active stream?

[cavernerg]

Yeah that is what I tried to explain. In this moments , snapshots are fine

[AlexxIT]

You have two examples in the go2rtc WebUI. Have you tried them both?

[cavernerg]

Yes , I did.
To me it seems like the camera needs too much time to wake up from standby

[AlexxIT]

I also think the camera is the problem.
The solution may be to skip the first X frames. But there are no plans for such a fix in the near future

[cavernerg]

Yeah I'd do that , if it was my own implementation of getting the snap, but I'm using octoprint/octoslack to do that. :(