include <opencv2 opencv.hpp="">

include <iostream>

#include <opencv2/opencv.hpp>
#include <iostream>

using namespace cv;
using namespace std;
 
std;


int err(String message) {
    cout << message << endl;
    return (1);
}
 
}

int main()
{
    VideoCapture playback("A.avi"); // playback video
    if (!playback.isOpened()) return err("playback did not open");
    VideoCapture cam(0); // camera
    if (!cam.isOpened()) return err("camera did not open");
 
open");

    // create GUI windows
 namedWindow("Frame");
 namedWindow("Video Frame");

 // please *avoid* Global variables
 Mat cam_frame, pb_frame; // current frames
 int keyboard = 0; // input from keyboard (raii)
 bool condition = false; // ???
 while ((char)keyboard != 'q' && (char)keyboard != 27) {
     cam >> cam_frame;
     if (cam_frame.empty())
         break;

     flip(cam_frame, cam_frame, 1);

     // no idea, what you have in mind, i'll use the space bar:
     if (keyboard==' ') condition = ! condition;
     if (condition) {
         playback >> pb_frame;
         if (pb_frame.empty()) { // end of movie, what now ? just rewind ?
             playback.set(CAP_PROP_POS_FRAMES, 0);
         } else { // only show, if valid
             imshow("Video Frame", pb_frame);
         }
     }

     imshow("Frame", cam_frame);
     keyboard = waitKey(30);
 }

 //destroy GUI windows
 destroyAllWindows();
 return EXIT_SUCCESS;
}
  
}