UVC Cam works on Windows 11, but does not on macOS 26

[baerenjagd]

Hello

I tried searching the forum for black screen, but could not find anything related to my problem.
I'm trying to connect a microscope cam to OBS 32.1 on macOS 26.2 Tahoe but I always get a black screen.

Same cam works flawless on Windows 11... I tried different settings like "OpenGL / Metal" but nothing works.

The only strange thing I noticed is that red line in the upper left corner (see screenshot).
It's not possible to pull / move it...

Any ideas?
Thanks!

Frank

 

[turingsroot]

That red line in the corner is usually the bounding box of a mismatched resolution. macOS UVC handling changed in Tahoe, some cheaper microscope cams that worked before don't negotiate the right format anymore.

Try this: open QuickTime Player > File > New Movie Recording, click the dropdown arrow next to the record button and select your microscope cam there. If it shows an image in QuickTime, the cam itself is fine and it's an OBS source config issue. If QuickTime also shows black, it's a macOS driver problem.

If QuickTime works, go back to OBS, remove the existing Video Capture Device source, re-add it and manually set the resolution to whatever your cam actually outputs (check its spec sheet, a lot of USB microscopes are 640x480 or 1280x720). The "Auto" setting sometimes picks a mode that the cam advertises but can't actually deliver on Mac.