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2017-06-27 07:39:34 -0500 commented question How to record multiple cameras with VideoWriter?

The connection to the cameras is via RTSP. I added the code

2017-06-26 12:30:37 -0500 asked a question How to record multiple cameras with VideoWriter?

Im having problems with VideoWriter class: I have multiple threads, and every one does:

  1. capture frame (VideoCapture)
  2. resize
  3. write frame (VideoWriter)

Every thread captures a different camera.

If I have 1 camera, the videos looks fine. With 2 cameras, the videos lose lots of frames in batches and start to have encode errors. With more cameras, the videos are even shorter and have lots more of corrupted frames.

I work on Ubuntu and my cameras are IP.

The video codec I need to use is h264. How can I get better videos? Or at least, videos with less FPS but not corrupted frames or frames lost in a batch?

Note: I tried to run 2 or more independent processes that captures and write one video each. Same behavior.

Edit: Code

#include <iostream>
#include <unistd.h>
#include <opencv2/opencv.hpp>

using namespace cv;
using namespace std;

string addr;
string outfile;

int main(int argc, char *argv[])

    addr = argv[1];
    outfile = argv[2];

    VideoCapture vcap(addr);
    Mat frame;

        VideoWriter writer(outfile,cv::VideoWriter::fourcc('X','2','6','4'),15,Size(1280,768));
        int i = 0;
        while( && i<20*60){
        cout << "Video couldnt open" << endl;

    return 0;