[opencv]3.获取摄像头的视频流

跟之前打开一段本地视频和一张图片一样，打开摄像头的视频流也是类似的。
这里就直接贴出代码块了。

#include "opencv2/highgui/highgui.hpp"
#include 

using namespace cv;
using namespace std;

int main(int argc, char* argv[])
{
    VideoCapture cap(0); // 打开摄像头0

    if (!cap.isOpened())  // 异常处理
    {
        cout << "Cannot open the video cam" << endl;
        waitKey(60000);
        return -1;
    }

    double dWidth = cap.get(CV_CAP_PROP_FRAME_WIDTH); //输入流的宽
    double dHeight = cap.get(CV_CAP_PROP_FRAME_HEIGHT); //输入流的高

    cout << "Frame size : " << dWidth << " x " << dHeight << endl;

    namedWindow("MyVideo", CV_WINDOW_AUTOSIZE); //创建一个窗体

    while (1)
    {
        Mat frame;

        bool bSuccess = cap.read(frame); // 获取一帧

        if (!bSuccess) //异常处理
        {
            cout << "Cannot read a frame from video stream" << endl;
            break;
        }

        imshow("MyVideo", frame); //显示获取到的视频帧

        if (waitKey(30) == 27) //按键退出
        {
            cout << "esc key is pressed by user" << endl;
            break;
        }
    }
    waitKey(60000);
    return 0;

}