c++ - Error while finding differences in frames from camera -

int main(int argc, char* argv[]) {     videocapture cap(0);     mat current_frame;     mat previous_frame;     mat result;      mat frame;      //cap.open(-1);     if (!cap.isopened()) {         //cerr << "can not open camera or video file" << endl;         return -1;     }      while(1)     {         cap >> current_frame;         if (current_frame.empty())             break;          if (! previous_frame.empty())  {             // subtract frames             subtract(current_frame, previous_frame, result);         }           imshow("window", result);         waitkey(10);          frame.copyto(previous_frame);      } } 

when run program subtract current frame previous frame , show resultant frame , show me error while start executing

unhandled exception @ 0x755d812f in wk01.exe: microsoft c++ exception: cv::exception @ memory location 0x001fe848..

and want apply same thing on recorded video

in 1st frame, result empty !

imshow("window", result); // crash 

also, you're copying empty frame mat previous_frame, should current_frame instead, no ?

try like:

   if (! previous_frame.empty())  {        // subtract frames        subtract(current_frame, previous_frame, result);        imshow("window", result);     }    waitkey(10);    current_frame.copyto(previous_frame);  }