VideoOutput -> ShaderEffectSource = white screen / colorful vertical stripes

[MHermann]

I am using ShaderEffectSource to display the VideoOutput of a usb camera.
Usually everything is working fine and the ShaderEffectSource is showing the live view of the camera.
But sometimes the live view of the camera is not shown. Instead it shows a white screen or colorful vertical stripes.

Does anybody now this problem?

Kind regards,
MHermann