...

Anyway, Real's RTSP uses some sort of cryptographic challenge-response deal [...]

That's already done in xine and works rather well.

Kudos to the "xine" developers for figuring this out. FYI, I plan to also implement this in the "LIVE.COM Streaming Media" libraries (the libraries that MPlayer uses to do RTSP/RTP streaming). I can't say yet when this will be available, though, because I generally give priority to (i) features that are requested by paying consulting clients, and (ii) features that implement open standard protocols. Non-standard, single-company-specific hacks like this tend to be lower-priority. BTW, questions about the LIVE.COM Streaming Media libraries (rather than questions specifically about MPlayer) are better-suited for the "live-devel" mailing list - see <http://lists.sourceforge.net/lists/listinfo/live-devel> for information. Ross.