opencv 从摄像头中读取视频并保存（c++版）

原文：http://blog.csdn.net/zhongshijunacm/article/details/68947890

OpenCV中的视频操作函数如下表所列：

VideoCapture 
VideoCapture::VideoCapture 
VideoCapture::open 
VideoCapture::isOpened 
VideoCapture::release 
VideoCapture::grab 
VideoCapture::retrieve 
VideoCapture::read 
VideoCapture::get 
VideoCapture::set 
VideoWriter 
VideoWriter::VideoWriter 
ReleaseVideoWriter 
VideoWriter::open 
VideoWriter::isOpened 
VideoWriter::write

感兴趣的可以自己查看官方文档。 
这里主要介绍几个本文中使用到的函数。

C++: VideoWriter::VideoWriter() 
C++: VideoWriter::VideoWriter(const string& filename, int fourcc, double fps, Size frameSize, bool isColor=true)

Parameters: 
filename – Name of the output video file. 
fourcc – 4-character code of codec used to compress the frames. For example, CV_FOURCC(‘P’,’I’,’M’,’1’) is a MPEG-1 codec, CV_FOURCC(‘M’,’J’,’P’,’G’) is a motion-jpeg codec etc. List of codes can be obtained at Video Codecs by FOURCC page. （如果，这里输入-1.在windows下会弹出一个对话框让你选择视频解压格式。） 
fps – Framerate of the created video stream. 
frameSize – Size of the video frames. 
isColor – If it is not zero, the encoder will expect and encode color frames, otherwise it will work with grayscale frames (the flag is currently supported on Windows only).

    //视频保存位置
    string outputVideoPath = "..\\images\\test.avi";  

    //打开摄像头
    VideoCapture capture0(0);  

    VideoWriter outputVideo;
    //获取当前摄像头的视频信息
    cv::Size S = cv::Size((int)capture0.get(CV_CAP_PROP_FRAME_WIDTH),
                          (int)capture0.get(CV_CAP_PROP_FRAME_HEIGHT));
    //打开视频路劲，设置基本信息 open函数中你参数跟上面给出的VideoWriter函数是一样的
    outputVideo.open(outputVideoPath, -1, 30.0, S, true);
    //CV_FOURCC('P','I','M','1')

    if (!outputVideo.isOpened()) {
        cout << "fail to open!" << endl;
        return -1;
    }

    cv::Mat frameImage;
    int count = 0;

    while(true) {
        //读取当前帧
        capture0 >> frameImage;

        if (frameImage.empty()) break;

        ++count;
        //输出当前帧
        cv::imshow("output", frameImage);
        //保存当前帧
        outputVideo << frameImage;

        if (char(waitKey(1)) == 'q') break;
    }

    std::cout << "TotalFrame: " << count << std::endl;