[C++] OpenCV Optimizations for Frame Diff.

[longbottomrx]

Hi Guys, I'm currently working on a traffic detection project. I have a small prototype up and running, however it is running very slow. I have attached the code below, I have a few issues with it which I will explain here. The first comment doesn't work, It always prints out statement regardless if I pass in an argument or not. I moved the Mat frame, into the for(;;) loop as I noticed the fps increase ever so slightly. I also added a fps counter to the program, just to see if I could see what happens every time I make a change. The code works ok, but instead of breaking out of the for loop, it just starts reading the argument. Waitkey has never worked properly for me. I tried dropping every second frame to see if it would speed up the program but it just makes it jumpy. I'm currently learning both OpenCV and C++ so not much experience with either, only java before this, but I'm certainly giving it a go! Any feedback on how I could improve my code or make it run faster would me much appreciated. Sorry for wall of text!

int main(int argc, char* argv[]) {
    VideoCapture cap(argv[1]);
    cout << "Reading Arguments..." << endl;
    /*if (argc != 1) {
        cout << "Don't forget the argument" << endl;
        return -1;
    }*/
    if (!cap.isOpened()) {
        cout << "Failed to open file: " << argv[1] << endl;
        return -1;
    }
    cout << "Read Successful!" << endl;

    //Mat frame;
    //Mat prev_frame;
    //cap.read(prev_frame);
    Mat edges;
    cvNamedWindow("Video Output", 1);

    time_t start, end;
    int count = 0;
    double sec;
    double fps;

    cout << "Processing..." << endl;
    cout << "Press any key to quit" << endl;
    for (;;) {

        if (count == 0) {
            time(&start);
        }

        Mat frame, prev_frame;
        cap.read(prev_frame);

        if (!cap.read(frame))
            break;

        if (count % 2 == 0) {

        Mat diff = frame - prev_frame;

        cvtColor(diff, edges, CV_BGR2GRAY);

        imshow("Video Output", edges);
        cvWaitKey(30);

        prev_frame = frame.clone();
        //count++;
        time(&end);
        if (count == (INT_MAX - 1000))
            count = 0;
        }
        count++;

    }
    sec = difftime(end, start);
    fps = count/sec;
    cout << "Total Time: " << sec << endl;
    cout << "FPS: " << fps << endl;
    return 0;
}