Icecast - Oct 2005 - forcing a source to use low quality

Hi,

On a shared server, we noticed some sources use 256Kbps (or more)
quality at 44100.
We would like to limit them in some way.
How could we? 
Say we want to allow only 22050 sourced stream (and lower), or something
like that...

-- 
Administration & Formation ? l'administration
de serveurs d?di?s:
http://www.google.fr/search?q=aspo+infogerance+serveur