title: On video streams (RTSP specifically) does grab returns the most recent frame?
body: <p>I'm using OpenCV to process a video stream that is provided via RTSP protocol. It's very easy to connect to the stream and read the frames. However, I'm having some timing issues and I want to make sure I'm doing it right.</p>
  <p>The question is: how does <code>VideoCapture::grab</code> works in RTSP streams regarding frame buffering - does it retrieves the most recent frame provided by the stream or does it retrieves frames from a buffer? If so, can I control the buffer?</p>