Creating simple video GIF previews with FFMpeg in PHP
This is split into two major parts:
I used the information I provide here: [1042433] Manipulating GIF Color Tables
The class does not create GIF data itself, it concats GIF images created by PHP's libraries into a working annimated GIF file.
This provides functions to get movie file information, to extract single frames from a movie file and to create an annimated square GIF with an annimated border from a movie file taking evenly distributed frames.