user35299: There is an article that says you can scale a video to be a multiple or fraction of the input size like this:
-vf "scale=iw/2:ih/2" to scale by half

Are there any other symbols for input variables in addition to iw and ih?
I've done multiple web searches and forum searches and I can't find anything that says what list of input values there are that are like ih and iw.
Thanks.

user1871: Documentation for ffmpeg is at http://www.ffmpeg.org/documentation.html
scale here refers to the scale filter, whose documentation is at http://www.ffmpeg.org/ffmpeg-filters.html#scale-1
The list of variables available in this filter is listed at the bottom of the Options section.

35299: <p>There is an article that says you can scale a video to be a multiple or fraction of the input size like this:</p>
<pre><code>-vf &quot;scale=iw/2:ih/2&quot; to scale by half
</code></pre>
<p>Are there any other symbols for input variables in addition to <code>iw</code> and <code>ih</code>?</p>
<p>I've done multiple web searches and forum searches and I can't find anything that says what list of input values there are that are like <code>ih</code> and <code>iw</code>.</p>
<p>Thanks.</p>
 1871: <p>Documentation for ffmpeg is at <a href="http://www.ffmpeg.org/documentation.html" rel="nofollow noreferrer">http://www.ffmpeg.org/documentation.html</a></p>
<p><code>scale</code> here refers to the scale filter, whose documentation is at <a href="http://www.ffmpeg.org/ffmpeg-filters.html#scale-1" rel="nofollow noreferrer">http://www.ffmpeg.org/ffmpeg-filters.html#scale-1</a></p>
<p>The list of variables available in this filter is listed at the bottom of the <a href="http://www.ffmpeg.org/ffmpeg-filters.html#Options-1" rel="nofollow noreferrer">Options</a> section.</p>
