opencv 将所有视频一起显示

Question

我正在编写一个 openCV 简单程序以单帧显示多视频。

我可以写两个视频，我想要 4 个视频，可以有人指导如何在单帧中显示 4 个视频。 下面是我的代码

 int main(int argc, char** argv)
 {
   string filename = "/home/user/testavicaravi.avi";
   VideoCapture capture(filename);

   VideoCapture capture1(filename);



   Mat frame;

   Mat frame1;


   if( !capture.isOpened() )
        throw "Error when reading steam_avi0";
   if( !capture1.isOpened() )
        throw "Error when reading steam_avi1";


   namedWindow( "w", 1);

   for( ; ; )
   {
       capture >> frame;
       capture1 >> frame1;

       if(frame.empty())
            break;

       if(frame1.empty())
           break;

       Mat canvas = Mat::zeros(frame.rows*2+1, frame.cols*2+1, frame.type());


       frame.copyTo(canvas(Range::all(), Range(0, frame.cols)));


       frame1.copyTo(canvas(Range::all(), Range(frame1.cols+1, frame1.cols*2+1)));
       // if it is too big to fit on the screen, then scale it down by 2, hopefully it'll fit :-)
       imshow("w", canvas);
   }
   waitKey(0); // key press to close window
   // releases and window destroy are automatic in C++ interface
 }

Answer 1

您正在解决这个问题的正确轨道上。 根据您希望如何显示 4 个视频（作为 2x2、1x4、4x1 矩阵），试试这个：

frame1, frame2, frame3, frame4 are frames read from cameras 1, 2, 3 and 4
For 1x4: canvas size = 
  cols = frame1.cols + frame2.cols + frame3.cols + frame4.cols
  rows = max(frame1.rows, frame2.rows, frame3.rows, frame4.rows)
  frame1.copyTo(canvas(Rect(Point(0,0), frame1.size())))
  frame2.copyTo(canvas(Rect(Point(frame1.cols,0), frame2.size())))
  frame3.copyTo(canvas(Rect(Point(frame2.cols,0), frame3.size())))
  frame4.copyTo(canvas(Rect(Point(frame3.cols,0), frame3.size())))

For 4x1: canvas size = 
  cols = max(frame1.cols, frame2.cols, frame3.cols, frame4.cols)
  rows = frame1.rows + frame2.rows + frame3.rows + frame4.rows)
  frame1.copyTo(canvas(Rect(Point(0,0), frame1.size())))
  frame2.copyTo(canvas(Rect(Point(0,frame1.rows), frame2.size())))
  frame3.copyTo(canvas(Rect(Point(0,frame2.rows), frame3.size())))
  frame4.copyTo(canvas(Rect(Point(0,frame3.rows), frame4.size())))

For 2x2: canvas size = 
  cols = max(frame1.cols, frame2.cols) + max(frame3.cols, frame4.cols)
  rows = max(frame1.rows, frame2.rows) + max(frame3.rows, frame4.rows)
  frame1.copyTo(canvas(Rect(Point(0,0), frame1.size())))
  frame2.copyTo(canvas(Rect(Point(frame1.cols,0), frame1.size())))
  frame3.copyTo(canvas(Rect(Point(0,max(frame1.rows, frame2.rows)), frame3.size())))
  frame4.copyTo(canvas(Rect(Point(frame3.cols,max(frame1.rows, frame2.rows)), frame4.size())))

不过，您可能需要考虑调整这些框架的大小，然后再将它们组合到一个大画布中，这样它们就可以全部放在一个屏幕中