|[1:00 PM] Users Behind a Firewall Rejoice! Apple Quietly Introduces HTTP Streaming Transport in QuickTime 4.1.1
by John F. Braun
Apple offered the 4.1.1 update to their QuickTime software in early April. Although there were several minor bug fixes, there is no mention, unless you do a bit of digging, of the additional ability to stream using HTTP.
Well, the 4.1.1 Readme does say "Improved streaming for corporate clients through better HTTP navigation," but we're not quite sure what this means. In any event, extensive testing of both the Mac and Windows 4.1.1 updates in the Mac Observer Labs show that streaming is now solidly supported via HTTP.
For the uninitiated, previous versions of QuickTime could only handle streaming content using the RTSP (Real Time Streaming Protocol) and RTP (Real-Time Transport Protocol) protocols. Despite being proposed standards, many firewalls either can't (due to bugs) or won't (due to IT paranoia or laziness) allow these protocols.
Although RTSP, typically using TCP port 554, isn't that much of a problem, the underlying RTP protocol (at least Apple's implementation) that actually moves the data can use any UDP port from 6970 through 6999.
QuickTime Settings Dialog Showing Transport Selection
If you go to the QuickTime Settings control panel, you'll notice a new category on the pulldown menu titled Streaming Transport. If you select it, you'll see your current setting, which is probably RTSP on port 554. Whatever it is, you should click on Auto Configure. It will test your connection and select the best possible way to move streaming data.
Although RTP using UDP provides the best performance, those who are behind a firewall can now use HTTP to view all of the cool channels Apple has been adding to their QuickTime TV offering.
Apple information on Firewalls and QuickTime 4
RFC 1889 - Real-Time Transport Protocol (RTP)
RFC 2326 - Real Time Streaming Protocol (RTSP)