title: How increase video speed into iOS without change video FPS?
body: <p>I made a video with 30FPS and 18s.
  I want increase x3 the video speed and get a new video with 6s (18s/3).</p>
  
  <p>I did the resolution bellow:</p>
  
  <pre><code>let newDuration = CMTimeMultiplyByFloat64(asset.duration, 1/3)
  compositionVideoTrack.scaleTimeRange(CMTimeRangeMake(kCMTimeZero, asset.duration)
                                          toDuration: newDuration)
  </code></pre>
  
  <p>The resolution is creating a new composition and scale the <code>CMTimeRange</code>.
  But the video result have x3 FPS too, the result video have 90FPS.</p>
  
  <p>I want a video result that has <strong>30FPS</strong> and <strong>6s</strong>, is it possible?</p>