We have a project called gyaro and you can test demo at [url removed, login to view]
currently we are facing some voice issues like no voice for few users and voice delay issues and when there are more then 30 users the chat slows down, its maybe because of chat history or private voice chats.
There are 2 audio codes nellymoser and speex which you need to work on, additionally you can create new audio codec.
This project uses php/mysql/red5 media server.
I am online for quick questions and answers.