After upgrading to 12.04 from 10.04, I'm experiencing a strange problem with my webcam. It appears that when capturing at 320x240, there is some kind of motion filter that stops the video from updating if there's not enough motion. The frame will freeze until I wave my hand in front of the camera, then it will capture a few frames and then stop.
I installed the V4L2 test utility and confirmed that the camera does not appear to send frames unless there's motion (the frame counter doesn't run continuously).
Strangely enough, when I change the resolution to 640x480, it captures fine at about 14fps. Unfortunately, google chat doesn't allow me to change the mode.
I installed the video4linux control panel and there doesn't seem to be any settings there that make a difference. I've googled around but can't seem to find a list of options to pass to the gspca driver.