Listing available devices in python-opencv

Question

I have two webcams attached to my laptop (one built in), both of which work. (If I use Cheese, a webcam thingy that comes with Ubuntu, it uses the external one). If I use

Answer 1

This is a general problem of the OpenCV, as you can see below. It seems that only the builtin, or the first USB cam (only if you do not have a buildin cam) works in OpenCV:

How to use a camera with OpenCV

Cannot access usb webcam through OpenCV, Cygwin

OpenCV capture from USB not iSight (OSX)

Currently, there is no way to extract the number of cameras, as listed in this feature request:

https://code.ros.org/trac/opencv/ticket/935