OpenCV not initializing USB camera

Question

I am trying to capture video from a USB camera using OpenCV.

#include <highgui.h>
#include <iostream>

using namespace std;
using namespace cv;

int main()
{
    VideoCapture cap (-1);
    if (!cap.isOpened())
         cout << "Cam initialize failed";
    else cout << "Cam initialized";

    return 0;
}

It is failing to initialize the camera. cap.isOpened() is returning zero.

The same program, with same version of OpenCV and the same USB camera, is correctly running in my friend's machine. I am running Fedora 16. The camera is properly working in another application (for example, Cheese).

I did some searching in Google and Stack Overflow. But no useful help. Any idea?

Answer 1

Try running your program as root. You may not have permission, and opencv doesn't tell you if thats the reason cap.isOpened() failed.