Finding out what the input parameter (which defaults to composite1, which didn’t work for my Creative Labs’ Webcam NX) should be was a little hard, so I’ll make a note of it for myself here: Urs Kradofler’s “WebCam under Linux” page says…
[…] do not use the option “input = composite1” as given in the man pages; enter the command v4lctl list to view a list of possibilities; in my case [the command input = Webcam was] ok.”
If you have multiple cameras, you can specify the device for v4lctl to look at by using the -c parameter (e.g. v4lctl -c /dev/video1 list).
For my Creative Lab’s NX the input parameter was to be ZC301-2 and, for my Philips Toucam II, Camera.