ffmpeg question running a command noob question

[iBuddy]

Here is the ffmpeg command that you write in SSH

ffmpeg -i source.mpg -ab 56 -ar 22050 -b 500  -s 320x240 destination.flv

Works great, I have no problems. However I dont want to manually do this, I want to create a PHP page to do it from.

If I were to have a PHP file, what would I write for the PHP to execute the above command?

Because when I put:

<?
ffmpeg -i source.mpg -ab 56 -ar 22050 -b 500  -s 320x240 destination.flv

?>

it says:

Parse error: syntax error, unexpected T_STRING in /home/account/public_html/test_media/convert.php on line 2

[iBuddy]

I foudn the code

<?PHP

$sourcemovie = "/home/account/public_html/test_media/AFVBabies_1.mpg";
$targetmovie = "/home/account/public_html/test_media/convert.flv";

$params = "";

$show = exec("ffmpeg -i ".$sourcemovie." ".$params." ".$targetmovie);
echo $show;

?>

However thats not working either, it says
built on Aug 12 2006 00:19:54, gcc: 3.4.5 20051201 (Red Hat 3.4.5-2)