How can I set drawtext fontsize in ffmpeg according to resolutions ratio
<p>How can I set fontsize for drawtext on video according to width and height of each resolutions, to a certain proportion?</p>

<pre><code>ffmpeg -i Input.mp4 -vf drawtext="fontfile=OpenSans-Regular.ttf: \
text='New Music Video': fontcolor=white: fontsize=?: r=25: box=1: boxcolor=black@0.3: \ boxborderw=3: x=(20)/2: y=(h-text_h-20) " Output.mp4
</code></pre>

<p>I ask this question because when I set it to 24 <code>fontsize=24</code> for example,it size is defferent at other resolutions,when convert is done.</p>