This is a module which allows the audio of a Audio/Video stream to stripped out and a new stream to be created so providing a lower bandwidth option without the need to send a separate stream.
It can be used in a variety of situations where a lower bandwidth option is required but no re-encoding is possible/wanted
The audio stream can also be sent to a Shoutcast server if it is a valid MP3 or AAC+ stream.
It can be downloaded from here along with the instructions
http://www.shamrock.org.uk/WowzaModules/AudioRepeater/
Shamrock