Trouble writing video to file using opencv

Question

I am trying to write a captured video to a file using OpenCV in C++ inside visualstudio 2013. Programs seems to capture the video from the webcam on my laptop and also able to save each frame a image but when I write the frames into a video file, I end up with a 6kb file. Program gives me no error as I have followed the instruction from the OpenCV document.

I am pasting the program for review. Please suggest how may I make it a successful program.

Thank you.

#include <stdio.h>
#include <iostream>
#include "opencv2\core\core.hpp"
#include "opencv2\highgui\highgui.hpp"

using namespace std;
using namespace cv;

int main()
{
    VideoCapture video_capture(0);

    if (!video_capture.isOpened())
    {
        cout << "Error in opening video feed!" << endl;
        getchar();
        return -1;
    }

    // Creating the window to view video feed
    String window_name = "Video_Feed";
    namedWindow(window_name, CV_WINDOW_AUTOSIZE);

    //
    Mat frame;

    // Filename
    String filename = "...\\first_recording.avi";

    // four character code
    int fcc = CV_FOURCC('M', 'P', '4', '2');

    // frames per sec
    int fps = 10;

    // frame size
    Size frame_size(CV_CAP_PROP_FRAME_WIDTH, CV_CAP_PROP_FRAME_HEIGHT);

    VideoWriter video_writer = VideoWriter(filename,fcc,fps,frame_size,true);

    if (!video_writer.isOpened())// || video_writer.isOpened == NULL)
    {
        cout << "Error in opening video writer feed!" << endl;
        getchar();
        return -1;
    }

    int frame_count = 0;

    while (frame_count < 100)
    {
        bool cap_success = video_capture.read(frame);

        if (!cap_success)
        {
            cout << "Error in capturing the image from the camera feed!" << endl;
            getchar();
            break;
        }

        imshow(window_name, frame);
        //imwrite("cap.jpg", frame);
        video_writer.write(frame);

        switch (waitKey(10))
        {
        case 27:
            return 0;
            break;
        }
        frame_count++;
    }

    //scvReleaseVideoWriter;
    destroyWindow(window_name);
    return 0;

}

Answer 1

Please find the below piece of code to write the video file.

 int main(int argc, char* argv[])
    {
        // Load input video
        cv::VideoCapture input_cap("test8.avi");
        if (!input_cap.isOpened())
        {
            std::cout << "!!! Input video could not be opened" << std::endl;
            return -1;
        }

    // Setup output video
    cv::VideoWriter output_cap("output.avi",  
                               input_cap.get(CV_CAP_PROP_FOURCC),
                               input_cap.get(CV_CAP_PROP_FPS), 
                               cv::Size(input_cap.get(CV_CAP_PROP_FRAME_WIDTH), input_cap.get(CV_CAP_PROP_FRAME_HEIGHT)));

    if (!output_cap.isOpened())
    {
        std::cout << "!!! Output video could not be opened" << std::endl;
        return -1;
    }

    // Loop to read frames from the input capture and write it to the output capture
    cv::Mat frame;
    while (true)
    {       
        if (!input_cap.read(frame))             
            break;

        output_cap.write(frame);
    }

    // Release capture interfaces   
    input_cap.release();
    output_cap.release();

    return 0;
}