Capture an RTP stream in OpenCV with GStreamer backend

opencv_rtp_capture.cpp

#include <opencv2/opencv.hpp>

int main( int argc, char ** argv )
{
  cv::VideoCapture cap;
  cv::Mat frame;

  const std::string windowName{ "RTP Capture" };
  cap.open( "udpsrc port=5000 caps = \"application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, payload=(int)96\" ! rtph264depay ! decodebin ! videoconvert ! appsink", cv::CAP_GSTREAMER );

  std::cout << "Opened " << cap.isOpened() << std::endl;
  for( cap >> frame; !frame.empty(); cap >> frame )
  {
    cv::imshow( windowName, frame );

    char key = cv::waitKey( 1 );
    if( key == 'q' || key == 27 )
      break;
  }

  cv::destroyWindow( windowName );
}

// Create RTP from camera with:
//   gst-launch-1.0 -v v4l2src ! videoscale ! 'video/x-raw,width=640,height=480' ! videoconvert ! x264enc tune=zerolatency bitrate=500 speed-preset=superfast ! rtph264pay ! udpsink host=127.0.0.1 port=5000