VIDEO FILTERS
Video filters allow you to modify the video stream and its properties. The syntax is:
-vf <filter1[=parameter1:parameter2:...],filter2,...>
Setup a chain of video filters.
-vop <...,filter2[=parameter1:parameter2:...],filter1> (OBSOLETE)
Setup a chain of video filters, to be applied in reverse order. Deprecated in favor of -vf.