在OpenCV中编写AVI文件

经过多次尝试,out.avi文件被写入0个字节.
我不知道我哪里错了.

以下是我使用的代码

int main(int argc,char* argv[]) {
    CvCapture* input = cvCaptureFromFile(argv[1]);
    IplImage* image = cvRetrieveFrame(input);

    if (!image) {
        printf("Unable to read input");
        return 0;
    }


    CvSize imgSize;
    imgSize.width = image->width;
    imgSize.height = image->height;



    double fps = cvGetCaptureProperty(
            input,CV_CAP_PROP_FPS
            );

    CvVideoWriter *writer = cvCreateVideoWriter(
            "out.avi",CV_FOURCC('M','J','P','G'),fps,imgSize
            );


    IplImage* colourImage;
    //Keep processing frames...
    for (;;) {

        //Get a frame from the input video.
        colourImage = cvQueryFrame(input);
        cvWriteFrame(writer,colourImage);

    }

    cvReleaseVideoWriter(&writer);
    cvReleaseCapture(&input);

}