Is there a way to add a “fade to black” effect to a video, from the command line?

Question

I have a script to encode videos (using mencoder), but is there a way to add a simple "fade out/in to black" from the command line, preferably free (as in open source).

It could be either on Windows or Ubuntu Linux.

Answer 1

The only thing I could find – based on the command line – is mmsuper8, a Linux tool.

Specifically, it features the mmsuper8fade tool, which seems like it could be useful for you.

_{Best would be if you edit this question and supply an example that worked for you!}