How do I access an external webcam with OpenCV?

Question

The big problem lies in the fact that the code, no matter which number I type in to VideoCapture cap(), it will always find the internal webcap of my laptop - Or die trying. I have tried going in to devices and deactivated the internal one, but it did little good. (By the way, I'm new at this forum, so be gentle.)

Here's the code ( Not including the Rotation function.)

int main()
{   
// NOW WITH WEBCAM INPUT!!
    VideoCapture cap(0);//capture image from webcam
    cap.open(true); 
    Mat image;
    cap>>image; //applying the captured image to Mat image
    //Mat image = imread("Tulips.jpg"); // reading the image
    double degrees; // Number of degrees we want to rotate the image
    double oregoX = image.cols / 2; //X-center of the image
    double oregoY = image.rows / 2; //Y-center of the image

//user inputs
cout << "please enter the number of degrees you wish to turn the image" << endl;
cin >> degrees;

cout << "\n\nplease enter at which point (X, Y) you want to rotate the image\n(make space not comma)\n" << endl;
cout << "The center of the image is at " << oregoX << ", " << oregoY << endl;
cin >> oregoX >> oregoY;

while (true){
    cap>>image;

    if (!image.data) break;
    if (waitKey(30) >= 0) break;

    cvtColor(image, image, CV_8U); //Converting image to 8-bit
    Mat grayImage; //creating a canvas for the grayscale image
    cvtColor(image, grayImage, CV_RGB2GRAY); //creating the grayscale image



    // Here we create a canvas with the same size as the input image, later to put in the rotated data
    Mat imageOut(grayImage.rows, grayImage.cols, CV_8U);



    Rotation(grayImage, imageOut, degrees, oregoX, oregoY); //Performing the rotation on the image using the Rotation() funcion

    imshow("The Gray Image", grayImage);
    imshow("The rotated image", imageOut);

}

}

Answer 1

Device manager -> Locate internal webcam -> Disable internal webcam. The default webcam will then become whichever webcam that you plug in afterwards.

Answer 2

VideoCapture cap(1); //capture image from other webcam