How to ad watermark ffmpeg

Here is my code .Please help me to ad a watermark when convert mp4 file .
Any type watermark , image.text,subtitle etc . we just need to ad our site link

    if($new_format=="mp4"){ $call=$ffmpeg." -i logo.png -filter_complex ".$video_to_convert."  -vcodec mpeg4 -r 30 -b ".$quality." -acodec libmp3lame -ab 126000 -ar ".$audio." -ac 2 -s ".$size." ".$converted_vids.$name.".".$new_format." -y 2> log/".$name.".txt";}

PHP:

 

Did you ever get help with this? I'm trying to add watermark function to uploading videos, via a php web script

 

You can do it via VLC media player
Tools -> Effects and filters -> Video effects tab -> Overlay
You can add image or text
And then Media -> Convert/save

 

use this

ffmpeg -i input.mp4 -i logo.png -filter_complex \
"overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2" \
-codec:a copy output.mp4

Code (markup):