Question / Help Webcams not shown when starting OBS

[juwo92]

Hey, I am new to this forum and i did not find any help by searching and trying it by myself.

When starting OBS, my webcams (Logitech C270 HD 720p and Aiglam Webcam 1080p) does not show any video output in the OBS screen.
Sometimes by restarting OBS, my 1080p Cam gives a video output in OBS, but most of the time, both cams are like "dead", although both cams LED for recording are on. Sometimes both cams work, but 90 % of the time at least one cam's video isnt in OBS visible.

All cams are in the scene I created yesterday and worked fine till i restarted my computer.
I don't have any other programs using the video output of the two webcams which may create a conflict.

Do you have any suggestions or a possible solution?
Many thanks in advance!

 

[juwo92]

Nobody?

 

[carlmmii]

When dealing with multiple USB webcams, you need to ensure that you're not requiring more USB bandwidth than your host controller can provide. There is a hard limit of 480mbps per controller for the USB2.0 spec, and for good connections that means you're lucky if you can get 2 webcams providing 1080p30 or 720p60 feeds.

The solution is always the same -- separate the webcams across multiple usb host controllers (use USBView to determine your topology), lower the resolution, or use a higher compression method for the webcam capture (MJPEG or H.264).

 

[juwo92]

Thanks for your reply! The strange thing is, that I tested XSplit for comparison and both webcams are showing up.
I now use the Logitech C920 and the Aiglam cam. The Aiglam cam does not show up in OBS. In XSplit it does.

Is OBS using anything different? I tested MJPEG for both cams in OBS without success.

I installed USB Viewer and thats what I got:

 

[carlmmii]

OBS and Xsplit may differ in the timing of when devices are activated. From what I've noticed from my own experience, any time I have multiple webcams on the same host controller, one of them will inevitably show black until I disable and re-enable within OBS. The same thing happens when switching scene collections, as it resets the activation for all devices.

From your USBview, you do in fact have both webcams connected to the same host controller. I do see that there is another host controller (up top) that has nothing connected -- see if you can figure out which ports are associated with that, and put one of your webcams there. That should fix your issues.