title: OpenCV: how to detect if video has fast moving object in it?
body: <p>What would be the best way to detect a fast moving object using OpenCV?</p>
  
  <p>Say, I have 5 random video files:</p>
  
  <p>1) Video of a crowd, people walking, static camera.
  2) Video of a cat playing with a ball, shaky iPhone camera.
  3) Video of a person being interviewed. Static camera.
  4) Animation (3D) of a fast moving car, background is blurred etc. etc.
  5) A blurred out video shot with iPhone camera (just camera waved around, nothing is visible).</p>
  
  <p>So I would like to isolate video5 and detect that there is a lot of movement in video4 and video2.</p>
  
  <p>What would be the best approach to do that? I think of using OpenCV2, but if there is a better solution for that, I'd be happy to learn about that. </p>
  
  <p>Any input greatly appreciated. Pseudo-code or just recommendations of specific algorithms.</p>
  
  <p>Thank you</p>