title: FFmpeg filter to rotate image around point
body: <p>Does anyone know how to rotate an image to its start point (top-left corner) instead of the center point (default) with the FFmpeg -vf rotate?</p>
  
  <p>In this example I try to rotate a red squared image (<strong>test_sq.png</strong>) <strong>30</strong> degrees from its start point on <strong>in.png</strong> placed at coord <strong>423:259</strong> resulting in <strong>out.png</strong>.</p>
  
  <p>This is my command:</p>
  
  <pre><code>ffmpeg -y -i in.png -pix_fmt bgra -strict experimental -vf movie=test_sq.png scale=279:279 rotate=30*PI/180:c=none:oh=ow [sticker]; [in][sticker] overlay=423:259 [out] -s 1280x720 out.png
  </code></pre>
  
  <p>To visualize it:</p>
  
  <p><img src="https://i.gyazo.com/a3060df36b5339b89798663732252196.png" alt="Results"></p>
  
  <p>As you can see it rotates from its center point and also clips the original image, not really good.
  Anyone have suggestions or ideas how to achieve what i need?</p>