OpenCV with Network Cameras

I enclosed C++ code for grabbing frames. It requires OpenCV version 2.0 or higher. The code uses cv::mat structure which is preferred to old IplImage structure.

#include "cv.h"#include "highgui.h"#include <iostream>int main(int, char**) {    cv::VideoCapture vcap;    cv::Mat image;    const std::string videoStreamAddress = "rtsp://cam_address:554/live.sdp";     /* it may be an address of an mjpeg stream,     e.g. "http://user:pass@cam_address:8081/cgi/mjpg/mjpg.cgi?.mjpg" */    //open the video stream and make sure it's opened    if(!vcap.open(videoStreamAddress)) {        std::cout << "Error opening video stream or file" << std::endl;        return -1;    }    //Create output window for displaying frames.     //It's important to create this window outside of the `for` loop    //Otherwise this window will be created automatically each time you call    //`imshow(...)`, which is very inefficient.     cv::namedWindow("Output Window");    for(;;) {        if(!vcap.read(image)) {            std::cout << "No frame" << std::endl;            cv::waitKey();        }        cv::imshow("Output Window", image);        if(cv::waitKey(1) >= 0) break;    }   }

Update You can grab frames from H.264 RTSP streams. Look up your camera API for details to get the URL command. For example, for an Axis network camera the URL address might be:

// H.264 stream RTSP address, where 10.10.10.10 is an IP address // and 554 is the port numberrtsp://10.10.10.10:554/axis-media/media.amp// if the camera is password protectedrtsp://username:password@10.10.10.10:554/axis-media/media.amp

#include <stdio.h>#include "opencv.hpp"int main(){    CvCapture *camera=cvCaptureFromFile("http://username:pass@cam_address/axis-cgi/mjpg/video.cgi?resolution=640x480&req_fps=30&.mjpg");    if (camera==NULL)        printf("camera is null\n");    else        printf("camera is not null");    cvNamedWindow("img");    while (cvWaitKey(10)!=atoi("q")){        double t1=(double)cvGetTickCount();        IplImage *img=cvQueryFrame(camera);        double t2=(double)cvGetTickCount();        printf("time: %gms  fps: %.2g\n",(t2-t1)/(cvGetTickFrequency()*1000.), 1000./((t2-t1)/(cvGetTickFrequency()*1000.)));        cvShowImage("img",img);    }    cvReleaseCapture(&camera);}

OpenCV can be compiled with FFMPEG support. From ./configure --help:

--with-ffmpeg     use ffmpeg libraries (see LICENSE) [automatic]

You can then use cvCreateFileCapture_FFMPEG to create a CvCapture with e.g. the URL of the camera's MJPG stream.

I use this to grab frames from an AXIS camera:

CvCapture *capture =     cvCreateFileCapture_FFMPEG("http://axis-cam/mjpg/video.mjpg?resolution=640x480&req_fps=10&.mjpg");