ok, it seems to be working, pretty easily for me; note, this code is a gross oversimplification of anything i would use in production; its just a little test script. <?php $sourceFile = $_GET['sourceFile']; $destFile = $_GET['destFile']; echo $sourceFile . ' ' . $destFile; if(is_file("./$sourceFile")) { echo 'source file is cool..'; $result = system("mencoder $sourceFile -o ./$destFile -ovc lavc -oac mp3lame"); var_dump($result); if($result && is_file("./$destFile")) { die("$destFile created successfully!"); } } die("$destFile could not be created!"); ?> here is the url i go to to trigger the script: http://localhost/mEncode.php?sourceFile=WindowsMedia.wmv&destFile=WindowsMedia.avi and heres the last bit of the output from the browser: WindowsMedia.avi created successfully! have you been trying to run the script from the cli, or from the browser? i would first try to run your php script from the cli; eg. php myMencoderScript.php <inputFile> <outputFile> if it works there, and not from the browser, id imagine its a permissions issue. but i was able to run my script from the browser, w/o altering the perms on the mencoder binary, as the stock perms on my box are: nathan@trident ~/Desktop $ ls -l /usr/bin/mencoder -rwxr-xr-x 1 root root 6637020 Jan 19 10:38 /usr/bin/mencoder you can find out what they are on your system by issuing; ls -l `which mencoder` if other is, r-x, you should be good to go. if your script isnt working from the cli then something probly needs to be cleaned up in there. try to make it as simple as possible to start out. once you get it working, you can add all the other features you want. -nathan