title: How can I speed up a video by dropping frames?
body: <p>I've got a video that's 30 minutes long. I want to make a speeded up version that's (say) 15 minutes long. I could do this by dropping every 2nd frame. How can I do this on linux?</p>
  
  <p>I'm playing with gstreamer and it looks cool. Is there a way to do this with gstreamer? What would be the <code>gst-launch</code> command line to do it?</p>
  
  <p>My source video is in Motion JPEG, so I do have the frames to drop. Even if it was using keyframes, there still should be a way to 'double speed' the film?</p>
  
  <p>I'd like a command line way to do this since I want to automate it.</p>