If video processing is what you want to do, I can very much recommend Avisynth[1] (and while it's Windows software, it runs quite well in Wine). For a more natively cross-platform alternative, there's also Vapoursynth[2], but I personally prefer Avisynth's DSL much more over Vapoursynth's Python scripting, not to mention it's generally got more filters available for it.
[1] http://avs-plus.net/ [2] http://www.vapoursynth.com/