title: How can I read a video file for use in openCV?
body: <p>I want to read a video file from an "avi file" and then enter it frame by frame to process it in openCV.
  How can I do that?
  Are there functions for that in openCV?  Should I use a video reading framwork?</p>
  
  <p>What are good frameworks for reading video files?</p>