Answers.Body: <p>The zoompan size parameter cannot be animated. It has to be a fixed numeral size of the form WxH, or a <a href="https://ffmpeg.org/ffmpeg-utils.html#Video-size" rel="nofollow noreferrer">size label</a> like hd1080.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-03-24T07:22:40.280Z
Answers.Text: Thank You again, Gyan!
  I was hoping to achieve less than 100% zoom without padding by tweaking output size )
Answers.UserDisplayName: Serge
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2019-03-24T07:14:07.500Z
Answers.LastActivityDate: 2019-03-24T07:14:07.500Z
Answers.UserDisplayName: Gyan
Body: <p>How is it possible to dynamically evaluate the <code>s</code> (output image size) parameter of ffmpeg <a href="https://ffmpeg.org/ffmpeg-filters.html#zoompan" rel="nofollow noreferrer">zoompan</a> filter on each frame?</p>
  
  <p>The parameter expectes its value in "WxH" format i.e. "1920x1080". 
  How to substitute an expression that would update the size as a function of, say, frame number?</p>
  
  <p>Couldn't find a way to concatenate strings.</p>
  
  <p>For a single number parameter I can do smth like <code>y='(out_h-in_h)/2'</code>, but how to take two expressions and join them with an "x" string?</p>
  
Tags: <ffmpeg>
Title: How to animate size parameter of ffmpeg zoompan filter?
UserDisplayName: Serge
ThreadText: # How to animate size parameter of ffmpeg zoompan filter?
  
  (Asked by: username_0 on 2019-03-24)
  
  How is it possible to dynamically evaluate the `s` (output image size) parameter of ffmpeg [zoompan](https://ffmpeg.org/ffmpeg-filters.html#zoompan) filter on each frame?
  
  The parameter expectes its value in "WxH" format i.e. "1920x1080".
  How to substitute an expression that would update the size as a function of, say, frame number?
  
  Couldn't find a way to concatenate strings.
  
  For a single number parameter I can do smth like `y='(out_h-in_h)/2'`, but how to take two expressions and join them with an "x" string?
  
  **Tags:** ffmpeg
  
  
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  ## 1 answers
  
  ### Answer by username_1 on 2019-03-24. Score: 1 | Accepted answer
  
  The zoompan size parameter cannot be animated. It has to be a fixed numeral size of the form WxH, or a [size label](https://ffmpeg.org/ffmpeg-utils.html#Video-size) like hd1080.
  
  > **Comments:**
  > **username_0**: Thank You again, username_1! I was hoping to achieve less than 100% zoom without padding by tweaking output size )  
  
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