im not an expert but i think this should work
Code:
<?php
$show = exec("/usr/local/bin/ffmpeg -i /home/youraccount/public_html/video.avi -ss 00:00:00 -t 00:30:00 -acodec mp3 -ar 22050 -ab 32 -f flv -s 320x240 /home/youraccount/public_html/video2.avi");
echo $show;
$show = exec("/usr/local/bin/ffmpeg -i /home/youraccount/public_html/video.avi -ss 00:30:00 -t 00:30:00 -acodec mp3 -ar 22050 -ab 32 -f flv -s 320x240 /home/youraccount/public_html/video3.avi");
echo $show;
?>
ss designates start time in move and t = duration
so that would take video.avi and split it into 2 files video1.avi and video2.avi