title: FFmpeg more than 1000 frames duplicated and input height doesn't match
body: <p>I'm currently using this code to record two windows side by side:</p>
  <pre><code>ffmpeg -f gdigrab -framerate 30 -i title=&quot;&quot; -f gdigrab -framerate 30 -i title=&quot;&quot; -c:v h264_nvenc -qp 0 -filter_complex hstack=inputs=2 2.mp4
  </code></pre>
  <p>However it throw this error after execution:</p>
  <pre><code>More than 1000 frames duplicated
  </code></pre>
  <p>Error Log: <a href="https://pastebin.com/gREVrKVK" rel="noreferrer">https://pastebin.com/gREVrKVK</a></p>
  <p>The <strong>first window</strong> mostly time is the same frame, maybe 1 frame change in each 3 sec.</p>
  <p>Another error in console is when the <strong>first window</strong> have a different height than second window, error:</p>
  <pre><code>[Parsed_hstack_0 @ 000002491166fd00] Input 1 height 500 does not match input 0 height 488.
  [Parsed_hstack_0 @ 000002491166fd00] Failed to configure output pad on Parsed_hstack_0
  </code></pre>
  <p>Error log: <a href="https://pastebin.com/vqdBPfpv" rel="noreferrer">https://pastebin.com/vqdBPfpv</a></p>
  <p>Looks like is not possible to record when they have different dimensions, so, if possible I would like to ask how to scale the first window to the same <strong>height</strong> (doesn't need to keep aspect ratio) of the second window, considering low CPU use above the video quality.</p>