Question

I’m using OpenCV to do some processing on an AVI file. Everything is working fine, except for the fact that only a small fraction of the frames in the original video are being captured.

Here’s an excerpt of my code:

capture=cvCaptureFromAVI(PATH_TO_VIDEO);
int fps=(int) cvGetCaptureProperty(capture,CV_CAP_PROP_FPS);
int frames=(int) cvGetCaptureProperty(capture,CV_CAP_PROP_FRAME_COUNT);
qDebug("%d frames at %d fps",frames,fps);
int framesSaved=0;

while(1) {
    frame=cvQueryFrame(capture);
    if(!frame) break;

    framesSaved++;
    data = (uchar *)frame->imageData;
    //PROCESSING
    cvWriteFrame(writer,frame);
}

cvReleaseVideoWriter(&writer);
qDebug("VIDEO SAVED: %d frames",framesSaved);

The output:

1948 frames at 50 fps
VIDEO SAVED: 105 frames

Any idea what the problem could be?

Thanks

Answer 1

OpenCV VideoCapture is known to have serious problems to report correct number of frames with CV_CAP_PROP_FRAME_COUNT

The good news is that the guys at OpenCV are working hard to fix it for the next release.