FFmpeg screen recording in grayscale to reduce file size?
<p>First off, I am unable to capture the screen of my Mac in grayscale. I've tried various combinations of <code>-pix_fmt gray</code> (for the input, for the output, and for both) but they never turn out grayscale.</p>

<p>Secondly, assuming I figure out how to do it, is it actually a viable option for reducing file size? I was surprised that reducing the frame rate (<code>-r</code>) did not affect file size (though <code>-size</code> did).</p>

<pre><code>ffmpeg -f avfoundation -pix_fmt gray -s 1440x900 -i 1 \
-pix_fmt gray -r 30 -preset ultrafast -b:v 5000k -t 5 out.mov
</code></pre>