title: fluent-ffmpeg aspect ratio with crop
body: <p>I am having trouble changing the aspect ratio between 16:9, 1:1 and 9:16 using <a href="https://www.npmjs.com/package/fluent-ffmpeg" rel="nofollow noreferrer">fluent-ffmpeg</a>
  When I try to change from 16:9 to 9:16, I kinda receive a squeezed video but actually I want the extra part should be removed.</p>
  
  <p>I tried this with many combinations:</p>
  
  <p><code>FFmpeg()
      .input(video)
      .size("608x?")
      .aspect("9:16")
      .output(tempFile)
      .run();</code></p>
  
  <p>My input 16:9 video 1920x1080
  <a href="https://i.stack.imgur.com/rD57f.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rD57f.png" alt="My input 16:9 video 1920x1080"></a></p>
  
  <p>.</p>
  
  <p>My Expected result 9:16 video 608x1080</p>
  
  <p><a href="https://i.stack.imgur.com/Ec3PF.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Ec3PF.png" alt="My Expected result 9:16 video 608x1080"></a></p>