Question

Please help me in achieving above task.I’m newbie to openCV. I have OpenCV 2.2 installed in my system and using VC++ 2010 Express as IDE. I don’t have inbuilt webcam in my laptop…
just i learnt how to load image. I’m very eager to load a video file from my disk(preferably mp4 , flv format) and wish to play it using openCV.

Answer 1

Using the C interface of OpenCV (which have worked better for me on Windows boxes), the function to load the video file is cvCaptureFromAVI(). After that, you need to use the traditional loop to retrieve frames throughcvQueryFrame() and then cvShowImage() to display them on a window created with cvNamedWindow().

CvCapture *capture = cvCaptureFromAVI("video.avi");
if(!capture)
{   
    printf("!!! cvCaptureFromAVI failed (file not found?)\n");
    return -1; 
}   

int fps = (int) cvGetCaptureProperty(capture, CV_CAP_PROP_FPS);
printf("* FPS: %d\n", fps);

cvNamedWindow("display_video", CV_WINDOW_AUTOSIZE);

IplImage* frame = NULL;
char key = 0;

while (key != 'q')
{   
    frame = cvQueryFrame(capture);
    if (!frame)
    {   
        printf("!!! cvQueryFrame failed: no frame\n");
        break;
    }

    cvShowImage("display_video", frame);

    key = cvWaitKey(1000 / fps);
}

cvReleaseCapture(&capture);
cvDestroyWindow("display_video");

This blog post brings a little extra info on the task you are trying to accomplish.