OpenCV Camera Capture

// Tested on Raspberry Pi 3

#include<stdio.h>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include "opencv2/opencv.hpp"

#include <iostream>

using namespace cv;
using namespace std;

int main( int argc, char** argv )
{
    int camid = 0;
    FILE *fp = fopen("config.txt", "rt");
    if(fp){
        fscanf(fp, "%d", &camid);
        fclose(fp);
    }

    cout << "Selecting camera " << camid << endl;
    // Load input video
    cv::VideoCapture input_cap(camid);
    if (!input_cap.isOpened())
    {
        std::cout << "!!! Input video could not be opened" << std::endl;
        return -1;
    }

    // Setup output video
    cv::VideoWriter output_cap(argv[1], 
               CV_FOURCC('D','I','V','X'),
               29,
               cv::Size(640,480));

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


    // Loop to read from input and write to output
    cv::Mat frame;

    while (true)
    {       
        if (!input_cap.read(frame))             
            break;
        output_cap.write(frame);
    }

    input_cap.release();
    output_cap.release();
    
   // the camera will be deinitialized automatically in VideoCapture destructor
    return 0;
}