RTSP protocol is used for years for streaming Real Video and Streaming Real Audio. And starting with Windows Media Player 9 Series, Windows Media Services 9 Series and Windows Server 2003 RTSP Protocol is now the default protocol for streaming Windows Media.
Windows Media Services 9 Series can use RTSP, HTTP, or MMS for streaming. It uses RTSP when trying to connect to Windows Media Player 9 Series. If that attempt is unsuccessful, the server uses MMS or HTTP to connect to the Player. This process is called rollover. Earlier versions of Windows Media Player do not support RTSP, but they do support MMS. If the server cannot connect to the Player by using MMS, then the server tries to connect using HTTP. Windows Media Player automatically tries to rollover to different protocols according to its Windows Media property settings.
Protocol rollover for Windows Media Series 9 for URLs starting with “mms://”:
1. RTSPU (RTSP using UDP)
2. RTSPT (RTSP using TCP)
3. MMSU (MMS using UDP)
4. MMST (MMS using TCP)
When Windows Media Player 9 Series accesses a stream from Windows Media Server 2003 with Windows Media Services 9 Series, it normally uses RTSP protocol and only uses MMS or HTTP protocols if a RTSP connection is not available. Old streaming media recording software as well as old versions of Windows Media Player can only download Windows Media streams using MMS or HTTP Protocols. In most cases streaming media recording works only because of the Protocol Rollover.0