Issues with OpenCV and RTSP

For months now I've been fighting with OpenCV to try and get a decent image coming through my internet camera and it's really beginning to drive me mad. I've got a reasonable little program to test the connection which looks like this:

/* 
 * File:   main.cpp
 * Author: Ryan
 *
 * Created on October 27, 2011, 2:23 PM
 */
#include <cstdlib>
#include "opencv2/core/core.hpp"
#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"
#include "opencv2/contrib/contrib.hpp"
#include "opencv2/features2d/features2d.hpp"
#include "opencv2/legacy/legacy.hpp"
#include "opencv2/video/tracking.hpp"
#include <stdio.h> 

using namespace std;
using namespace cv;

int main() {
// CvCapture *camera = cvCreateFileCapture("/home/ryan/NetBeansProjects/OpenRTSP/video-H264-1");
// CvCapture *camera = cvCreateFileCapture("stream_fifo");    
// CvCapture *camera = cvCreateFileCapture("Wildlife.wmv");
   CvCapture *camera = cvCreateFileCapture("rtsp://admin:admin@192.168.1.128/ch1-s1"); //purple cam /?tcp
// CvCapture *camera=cvCreateFileCapture("http://192.168.1.5/image.jpg"); //black cam
// CvCapture *camera = cvCreateCameraCapture(0); //built in cam
// cvWaitKey(10000); 
    if (camera == NULL) {
        printf("camera is null, aborting...");
        return -1;
    }
    printf("camera is not null\n");
    fflush(stdout);
    cvNamedWindow("img");
    int i = 0;
    while (cvWaitKey(100) != 27) {
 // CvCapture *camera=cvCreateFileCapture("http://192.168.1.5/image.jpg");
        IplImage *img = cvQueryFrame(camera);
            if (img == NULL) break;
        cvShowImage("img", img);
// cvReleaseCapture(&camera); 
// printf("Image: %i\n", ++i);
        }
    cvReleaseCapture(&camera);
    return 0;
}

You'll probably notice in there quite a few lines of commented code, this is just me trying out different ways of creating camera connections for different cameras and also a few little tests on reading from file. I know this code works as it loads up and plays the 'Wildlife.wmv' nicely, albeit without sound but that is expected and I can live without sound for now.

The problem comes when I try and play the video at the end of the RTSP link. Everything is set properly in the URL 'rtsp://admin:admin@192.168.1.128/ch1-s1' which follows the 'rtsp://username:password@ip.address.to.media/channel-stream' format and the OpenCV documentation says that this should work but what results is the most broken, artifact-riddled mess I've ever had the misfortune to lay eyes on. I mean look at this:

What on earth am I meant to do with that?

Whilst opening the stream in Quicktime gives me this (and notice this is after 5 hours of continuous streaming and the image has hardly faltered):

Even FFMPEG, the underlying technology used by OpenCV for its RTSP support gives me a decent stream even though it does seem to crash after 10 seconds (created using the command 'ffplay rtsp://admin:admin@192.168.1.128/ch1-s1' more on the crashing later perhaps):

And finally we have the camera's own video player which is embedded in the html (from what I can see it is an OCX plugin calling on a few .dlls). Perhaps unsurprisingly this gives a perfect stream as well:

So why in the world does OpenCV make such a mess of it? I'm still trying to find out...

Filed under in-betweeners as the connection does actually work, it's just rubbish!