How do I crop out Region of Interest (ROI) from .mp4 video using FFMPEG?
The crop filter arguments specify a crop window of the given width and height whose top-left corner is at co-ordinates (x, y) measured from top-left corner of the input frame. The entire crop window must be contained within the frame. So, to start with, w &lt;= iw &amp;&amp; h &lt;= ih. 

Then, x+w &lt;= iw &amp;&amp; x &gt;= 0 and y+h &lt;= ih &amp;&amp; y &gt;= 0. If this condition isn't meant, x or y will be adjusted to auto-center the crop window along that axis, e.g. for a 100x100 input, if w = 50 and x = 60, then x is adjusted to (100-50)/2 = 25.