how to watermark mp4 video with ffmpeg php

I need to watermark a mp4 video , Currently i am using this code, but it is not working , please solve this

<? exec('ffmpeg -i movie.mp4 -i logo.png -filter_complex overlay output.mp4');?>

Answer

You need to put the filter code within double quotes. If you could share more about the error you’re facing, I’ll be able to help you better.

<? exec('ffmpeg -i movie.mp4 -i logo.png -filter_complex "overlay" output.mp4');?>