c++ - How to count cameras in OpenCV 2.3?

Question

I want to get the number of available cameras.

I tried to count cameras like this:

for(int device = 0; device<10; device++) 
{
    VideoCapture cap(device);
    if (!cap.isOpened())
        return device;          
}

If I have a camera connected, it never failed to open. So I tried to preview different devices but I get always the image of my camera.

If I connect a second camera, device 0 is camera 1 and device 1-10 are camera 2.

I think there is a problem with DirectShow devices.

How to solve this problem? Or is there a function like in OpenCV1 cvcamGetCamerasCount()?

I am using Windows 7 and USB cameras.

Answer 1

OpenCV still has no API to enumerate the cameras or get the number of available devices. See this ticket on OpenCV bug tracker for details.

Behavior of VideoCapture is undefined for device numbers greater then number of devices connected and depends from API used to communicate with your camera. See OpenCV 2.3 (C++,QtGui), Problem Initializing some specific USB Devices and Setups for the list of APIs used in OpenCV.