Need help (suggestions for books, websites, etc.) learning about RTP / RTCP

I have been invited to work on what should be a simple application
that receives RTP audio and video streams and stores them on disk,
then serves them back on demand.

The platform is either VxWorks, LynxOS, or RTLinux, they haven't
decided yet which they want to use, but they would like the
implementation to be POSIX-compliant.

No signaling is involved; just receive the stream, store it on disk,
and serve it up on request.

I have a lot of experience in real time embedded software and some
experience in TCP / UDP / IP networking, but none in RTP or RTCP.

Can any of you recommend some good books or websites or online
tutorials that will help me learn what I need to learn to do this?

Thanks...