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Hi,

I have a tracking algorithm with two main parts; 1. tracking algorithm 2. video overlay.

A lot of stuff needs to be overlayed and it takes a lot of time. I was thinking of parallelizing the two parts using openMP with minimal effort. So I thought of using the sections directive available in openMP. The following code is just a crude form of what I am trying to achieve:

#include "opencv2\highgui\highgui.hpp"
#include "opencv2\core\core.hpp"
#include "opencv2\imgproc\imgproc.hpp"
#include <iostream>
#include <omp.h>
#include "Timer.h"

using namespace std;
using namespace cv;

int main()
{
    VideoCapture cap(0);        //start the webcam
    Mat frame, roi;
    Timer t;                    //timer class
    int frameNo = 0;
    double summ = 0;

    while (true)
    {
        cap >> frame;
        frameNo++;
        roi = frame(Rect(100, 100, 300, 300)).clone();  //extract a deep copy of region of interest; for tracking purposes
        t.start();                                      //start the timer
#pragma omp parallel sections
        {
#pragma omp section         //first section: tracking algorithm
            {
                //some tracking algorithm below which uses only "roi" variable
                GaussianBlur(roi, roi, Size(5, 5), 0, 0, BORDER_REPLICATE);
            }
#pragma omp section         //second section: overlay video
            {
                //a lot of overlay in different video parts which uses only "frame" variable
                putText(frame, "string 1", Point(10, 10), 1, 1, Scalar(1));
                putText(frame, "string 2", Point(20, 20), 1, 1, Scalar(1));
                putText(frame, "string 3", Point(30, 30), 1, 1, Scalar(1));
                putText(frame, "string 4", Point(40, 40), 1, 1, Scalar(1));
                putText(frame, "string 5", Point(50, 50), 1, 1, Scalar(1));
                putText(frame, "string 6", Point(60, 60), 1, 1, Scalar(1));
                putText(frame, "string 7", Point(70, 70), 1, 1, Scalar(1));
                putText(frame, "string 8", Point(80, 80), 1, 1, Scalar(1));
                putText(frame, "string 9", Point(90, 90), 1, 1, Scalar(1));
                putText(frame, "string 10", Point(100, 100), 1, 1, Scalar(1));
            }
        }
        t.stop();               //stop the timer

        summ += t.getElapsedTimeInMilliSec();
        if (frameNo % 10 == 0)      //average total time over 10 frames
        {
            cout << summ / 10 << endl;
            summ = 0;
        }
        imshow("frame", frame);
        if (waitKey(10) == 27)
            break;
    }
    return 0;
}

I don't seem to see a performance boost with timing analysis and in some cases the timing with openMP gets worse even when I am using different variables in my sections

My question is whether I am using the right approach (using sections directive) for my case or is there a better way to parallelize my existing code using openMP with minimal effort?

Thanks.