AMIP Dynamic Signature, How to output the file extension? Options

[eNforcer]

In the top left of the output file, how can I add the file extension such as MP3 or FLAC? (in uppercase also)

Edit:
Well, I'm no programmer but I have got this far:

I added this line to amipweb.conf
-d "ext=&func_ue(%ext)"

And this to Signature.php
$SONG[ext]

Just need to get it uppercase

[Serge]

use

-d "ext=$ue($uc(%ext))"

or in PHP:

$SONG[ext] = strtoupper($SONG[ext]);