Measure OpenCV FPS

Question

I\'m looking for a correct way to measure openCV FPS. I\'ve found several ways to do it. but none of them looks right for me.

The first one I\'ve tested, uses ti

Answer 1

I would just measure the walltime and simply divide the frames by time elapsed. On linux:

/*
* compile with:
*   g++ -ggdb webcam_fps_example2.cpp -o webcam_fps_example2 `pkg-config --cflags --libs opencv`
*/

#include "opencv2/opencv.hpp"
#include 
#include 


using namespace cv;
using namespace std;

double get_wall_time(){
    struct timeval time;
    if (gettimeofday(&time,NULL)){
        //  Handle error
        return 0;
    }
    return (double)time.tv_sec + (double)time.tv_usec * .000001;
}


int main(int argc, char** argv)
{
    VideoCapture cap;
    // open the default camera, use something different from 0 otherwise;
    // Check VideoCapture documentation.
    if(!cap.open(0))
        return 0;

    cap.set(CV_CAP_PROP_FRAME_WIDTH,1920);
    cap.set(CV_CAP_PROP_FRAME_HEIGHT,1080);

    double wall0 = get_wall_time();
    for(int x = 0; x < 500; x++)
    {
          Mat frame;
          cap >> frame;
          if( frame.empty() ) break; // end of video stream
          //imshow("this is you, smile! :)", frame);
          if( waitKey(10) == 27 ) break; // stop capturing by pressing ESC 
    }
    double wall1 = get_wall_time();
    double fps = 500/(wall1 - wall0);
    cout << "Wall Time = " << wall1 - wall0 << endl;
    cout << "FPS = " << fps << endl;
    // the camera will be closed automatically upon exit
    // cap.close();
    return 0;
}

Wall Time = 43.9243 FPS = 11.3832