Script to watermark animated GIFs

I need a script to watermark animated gifs. We have tried different solutions but nothing worked. The script file will be called from the admin panel. We have a list of animated gifs on the admin panel with a watermark button, it will post-pass the id of the current gif to the script file to watermark it. I need just the script file, the rest i can do it myself. You will have to let me test it on your own server, uploading custom gif and watermark and run the script. The watermark will be transparent png with the name of the website at the bottom left. Please just bid only if you are able to get this, please document yourself before. Thanks!