尽管cvWriteToAVI,OpenCV VideoWriter不会写任何东西

Question

我一直在尝试从凸轮捕获视频并将其写入AVI文件.我在Windows 7上使用Qt 4.8.2和MSVC 2010(x86).我有两个版本的代码:一个使用cv :: Mat,另一个使用IplImage*.但是,只有IplImage*版本正在运行.这是我使用cv :: Mat的代码:

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>

using namespace cv;

int main() {
    VideoCapture* capture2 = new VideoCapture( CV_CAP_DSHOW );
    Size size2 = Size(640,480);
    int codec = CV_FOURCC('M', 'J', 'P', 'G');
    VideoWriter* writer2 = new VideoWriter("video.avi",codec,15,size2);

    int a = 100;
    Mat frame2;
    while ( a > 0 ) {
        capture2->read(frame2);
        writer2->write(frame2);
        a--;
    }

    writer2->release();
    capture2->release();
    return 0;
}

这是使用IplImage*的代码:

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>

int main() {
    CvCapture* capture = cvCaptureFromCAM( CV_CAP_DSHOW );
    CvSize size = cvSize(640,480);
    int codec = CV_FOURCC('M', 'J', 'P', 'G');
    CvVideoWriter* writer = cvCreateVideoWriter("video.avi",codec,15,size);

    int a = 100;
    while ( a > 0 ) {
        IplImage* frame = cvQueryFrame( capture );
        cvWriteToAVI(writer,frame);
        a--;
    }

    cvReleaseVideoWriter(&writer);
    cvReleaseCapture( &capture );
    return 0;
}

它基本上是相同的,或者至少对我来说看起来是一样的.它读取100帧,并应将它们写入"video.avi".它编译并运行没有错误,但cv :: Mat版本没有写任何东西,并且IplImage*版本完美运行.

有人知道发生了什么事吗？

Answer 1

Opencv C++参考中的语法略有不同,这里是C++中的工作代码.我刚刚添加了imshow和waitkey,如果你愿意,可以删除它们.

int main()
{
    VideoCapture* capture2 = new VideoCapture(CV_CAP_DSHOW);
    Size size2 = Size(640, 480);
    int codec = CV_FOURCC('M', 'J', 'P', 'G');
    // Unlike in C, here we use an object of the class VideoWriter//
    VideoWriter writer2("video_.avi", codec, 15.0, size2, true);

    writer2.open("video_.avi", codec, 15.0, size2, true);
    if (writer2.isOpened())
    {
        int a = 100;
        Mat frame2;
        while (a > 0)
        {
            capture2->read(frame2);
            imshow("live", frame2);
            waitKey(100);
            writer2.write(frame2);
            a--;
        }
    }
    else
    {
        cout << "ERROR while opening" << endl;
    }

    // No Need to release the Writer as the distructor will called automatically
    capture2->release();

    return 0;
}