#include <opencv2/cudaoptflow.hpp>

#include <opencv2/cudaimgproc.hpp>

#include <opencv2/highgui.hpp>

#include <opencv2/imgproc.hpp>

#include <opencv2/optflow.hpp>

#include <iostream>

using namespace std;

using namespace cv;

int main(int argc, char** argv)

{

    cout << "OpenCV version: " << CV_VERSION << endl;

    VideoCapture capture;

    char* video = argv[1];

    capture.open(video);

    if(!capture.isOpened()) {

        fprintf(stderr, "Could not initialize capturing..\n");

        return -1;

    }

    Mat frame;

    cuda::GpuMat d_frame, d_prev_grey, d_grey, d_flow;

    int frame_num = 0;

    for(;;)

    {

        // get a new frame

        capture >> frame;

        if(frame.empty())

            break;

        frame_num++;

        d_frame.upload(frame);

        if (frame_num == 1)

        {

            cuda::cvtColor(d_frame, d_prev_grey, CV_BGR2GRAY);

            continue;

        }

        cuda::cvtColor(d_frame, d_grey, CV_BGR2GRAY);

        // compute optical flow

        //cv::calcOpticalFlowFarneback(prev_grey, grey, flow, 0.5, 3, 15, 3, 7, 1.5, OPTFLOW_FARNEBACK_GAUSSIAN);

        Ptr<cuda::BroxOpticalFlow> broxFlow = cuda::BroxOpticalFlow::create();

        broxFlow->calc(d_prev_grey, d_grey, d_flow);

        // assign new img to old img

        d_prev_grey.swap(d_grey);

    }

}