How to put text watermark on video using PHP in shared hosting

I am making video uploading site in shared hosting using PHP and I want users to upload their videos, and I want to put logo watermark to appear automatically on every video uploaded to site.

I don't want to use any API for this, please help

I have tried to put watermark on images using:

imagecopy();

& it worked fine.

Please suggest some framework, library, tutorial, reference or script which work for videos.