Hi, ive recently been commissioned to make a website for an online media publisher, a requirement of the site is that the publisher wish to be able to stream audio/video (screen casts) live. Ive been researching how to do this but have had little luck so far, so i was wondering if anyone has any knowledge of this and can recommend any online information/books that could help or could provide me with a basic overview of how it can be done so that i can further research.

Even information of how radios broadcast live on the Internet would be useful
Thanks in advance.