I am attempting to run the following via a php page:

<?php
exec("cvlc dvb:// :dvb-adapter=1 :no-video --sout 
'#standard{access=http,mux=asf,dst=10.10.1.53:8181}'
  ");
?>


This works fine using php on the command line, but not via a browser. 
The vlc process launches, but it does not actually stream. I'm guessing 
it is an environment variable or need for a shell. An ideas what I am 
missing?