Question / Help Webcam flickering because of brightness?

judohippo

judohippo

New Member
Hey folks,

I have a weird problem where when webcam is set to 720p it flickers like mad. If I lower the exposure it will stop. Or if I lower the resolution it'll stop.

I made a video of the problem here: https://youtu.be/z79OHea1qbk

I've tried multiple cameras and this happens with all of them.


Windows 10
MS Lifecam HD 3000
OBS Studio : 20.1.3
 
Banyarola

Banyarola

Active Member
I had the same problem and found out it was a bandwidth problem...
Try another USB port..
I ended up buying a dedicated usb card that had plenty of bandwidth.
 
judohippo

judohippo

New Member
@Banyarola Ok, I bought a powered usb and tried pluggin it in there, and everything else I have in there and the cam on the computer but still the same problem.
 
Banyarola

Banyarola

Active Member
I wouldn't advise buying anything else until you are sure your computer has the horsepower to handle it.
Maybe someone else here can help you better then I can..
I think you should post a log also so they can look at it.

In OBS go to HELP/LOG FILES and u/l your current log and then post the link here...
 
Suslik V

Suslik V

Active Member
If @Banyarola right, (I think he is right) then you can calculate the bandwidth you need (YUY2 is 4:2:2) with the formulas: Audio Clipping caused by Webcam?

Exposure has direct influence on the camera frame rate. The highest fps is just max available fps. Maybe it (edit: obs) uses IAMVideoControl::GetMaxAvailableFrameRate method (but I didn't found this part in the code). Anyway, check it manually, if your device has enough bandwidth to operate at given format and fps.
 
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judohippo

judohippo

New Member
So dumb question. The camera is the only usb device I have plugged in. Shouldn't there be enough bandwidth then to handle it? It's seems a bit crazy that a modern computer can't manage to display a webcam properly.
 
Suslik V

Suslik V

Active Member
If you don't want to provide the log-file say at least frame size, fps and USB port type (2.0 for example). Camera can show normal but you need right setting (compression, for example). Did you read the given links?

Edit: As far as I know, the big cameras captured by HDMI capture card installed in the recording/streaming PC. (if you need perfect quality).
 
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S

sam686

Member
The camera's limited USB 2.0 speed, and drivers doing the decompression might be the problem.
Try uninstall the Lifecam 3000 drivers to check if it gives you an option for MJPG or other formats in OBS-Studio.

I see this type of corruption in one of the frames from your first post of YouTube video.
corrupt_block.jpg

This is in a block size of probably 8x8 if not scaled. This also shifts the video and sometimes changes colors over everything on the right side and below it. Seeing corruption like this can only mean one thing: video compression is being used by hardware due to limited USB 2.0 speed, and the drivers are the one that are converting MJPG (or whatever it uses) back to YUY2, making OBS-Studio see it as YUY2.

Video compression is also the reason for darkening the camera settings that can reduce the flickering, there are less things to compress.

Multiply resolution, frame rate, and colorspace size...
1280x720x30x2 (2 bytes per pixel for YUY2) = 55296000 bytes per second, or 55.296 MB/s
This might be pushing past the limit of bandwidth if USB protocol overhead is taken account of.
https://www.google.com/search?q=USB+2.0+protocol+overhead
 
judohippo

judohippo

New Member
Suslik V

Suslik V

Active Member
While only YUY2 available for you, the only option is left - is to lower resolution and lower frame rate. The second device that sharing the bus is build-in mic.
 
M

mpawlick

New Member
PS couldnt you just disable the (in my struggling case: Razer Kiyo): audio device
in control panel and leave the rest alone (ie leave
under webcams: *insert* video device)
 
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