Video capture and save using OpenCV

Question

Given below is the code that I am using for getting the video from my webcam and saving it on my hard disk. On running the program it says "Video writer is not opening". Where am I going wrong?

#include <opencv\cv.h>
#include <opencv2\highgui\highgui.hpp>
#include <opencv2\imgproc\imgproc.hpp>
#include <WinSock2.h>
#include <WS2tcpip.h>
#include <stdio.h>
#include <iostream>

#pragma comment(lib, "Ws2_32.lib")
#define default_buflen 1024

using namespace std;
using namespace cv;

#define default_port "1234"

int main(int argc, char** argv)
{
    Mat capture;
    VideoCapture cap(0);
    if(!cap.isOpened())
    {
        cout<<"Cannot connect to camera"<<endl;
        getchar();
        return -1;
    }
    double fps=30;
    Size s=Size((int)cap.get(CV_CAP_PROP_FRAME_WIDTH),(int)cap.get(CV_CAP_PROP_FRAME_WIDTH));
    VideoWriter vidcapt;
    vidcapt.open("c:\\out.avi",CV_FOURCC('D','I','V','X'),cap.get(CV_CAP_PROP_FPS),s,true);

    if(!vidcapt.isOpened())
    {
        cout<<"Video writer not opening"<<endl;
        getchar();
        return -1;
    }

    while(true)
    {
        cap>>capture;
        namedWindow("Display",1);
        imshow("Display",capture);

        vidcapt<<capture;

        int ch=waitKey(5);
        if(char(ch)==27)
        {
            break;
        }
    }
}

I have read the answer given here and here but am not understanding where I am going wrong.

Answer 1

As per your code I can not understand why you created window Display every time in while loop, Also you initialize the VideoWriter object every time it may be wrong. I have slightly modified your code as below please try, it may it help you

    #include <opencv\cv.h>
    #include <opencv2\highgui\highgui.hpp>
    #include <opencv2\imgproc\imgproc.hpp>
    #include <WinSock2.h>
    #include <WS2tcpip.h>
    #include <stdio.h>
    #include <iostream>

    #pragma comment(lib, "Ws2_32.lib")
    #define default_buflen 1024

    using namespace std;
    using namespace cv;

    #define default_port "1234"

    int main(int argc, char** argv)
    {
        Mat capture;
        VideoCapture cap(0);
        if(!cap.isOpened())
        {
            cout<<"Cannot connect to camera"<<endl;
            getchar();
            return -1;
        }

  namedWindow("Display",CV_WINDOW_AUTOSIZE); 

  double dWidth = cap.get(CV_CAP_PROP_FRAME_WIDTH); 
  double dHeight = cap.get(CV_CAP_PROP_FRAME_HEIGHT); 

  Size frameSize(static_cast<int>(dWidth), static_cast<int>(dHeight));

  VideoWriter oVideoWriter ("c:\\out.avi", CV_FOURCC('P','I','M','1'), 20, frameSize,true);

   if ( !oVideoWriter.isOpened() ) 
   {
      cout << "ERROR: Failed to write the video" << endl;
      return -1;
    }

    while(true)
    {
          Mat frame;

          bool bSuccess = cap.read(frame); // read a new frame from video

          if (!bSuccess) //if not success, break loop
          {
             cout << "ERROR: Cannot read a frame from video file" << endl;
             break;
          }

          oVideoWriter.write(frame); //writer the frame into the file

         imshow("Display", frame); 

         if (waitKey(10) == 27) 
         {
            cout << "esc key is pressed by user" << endl;
            break; 
         }
      }
  }

Answer 2

Try other codecs

CV_FOURCC('P','I','M','1') = MPEG-1 codec

CV_FOURCC('M','J','P','G') = motion-jpeg codec (does not work well)

CV_FOURCC('M', 'P', '4', '2') = MPEG-4.2 codec

CV_FOURCC('D', 'I', 'V', '3') = MPEG-4.3 codec

CV_FOURCC('D', 'I', 'V', 'X') = MPEG-4 codec

CV_FOURCC('U', '2', '6', '3') = H263 codec

CV_FOURCC('I', '2', '6', '3') = H263I codec

CV_FOURCC('F', 'L', 'V', '1') = FLV1 codec

Copy pasted from here. I managed to write video with CV_FOURCC('F', 'L', 'V', '1').

By the way, codecs should be installed on your machine of course.