You can use Real Time Streaming Protocol (RTSP) to deliver
content as a unicast stream. It is an
application-level protocol that was created specifically to control
the delivery of real-time data, such as audio and video content. It
is implemented over a correction-oriented transport protocol. It
supports player control actions such as stopping, pausing,
rewinding, and fast-forwarding indexed Windows Media
files. You can use RTSP to stream content to
computers running Windows Media Player 9 Series or later or Windows
Media Services 9 Series. RTSP is a control protocol that works in
tandem with the data delivery Real Time Protocol (RTP) to provide
content to clients.
If the connection URL uses RTSP (for example,
rtsp://server_name/publishing_point_name/file_name), RTSP
automatically negotiates the best delivery mechanism for the
content. It then directs the RTP protocol to deliver streaming
content using the User Datagram Protocol (UDP) or using a
Transmission Control Protocol (TCP)-based protocol on a network
that does not support UDP.
If you want to force the server to use a specific protocol, you
can identify the protocol to be used in the announcement file. The
user can also specify the protocol in the content address (for
example,
rtspu://server_name/publishing_point_name/file_name). To
facilitate protocol rollover, it is recommended that the URL use
the generalized RTSP protocol. That way, the Player can use either
the RTSPU or RTSPT protocols to connect to the stream. If the
Player cannot connect to the stream successfully by using either of
the RTSP protocols, it attempts to connect to the stream by using
one of the MMS protocols. For more information about protocol
rollover, see How protocol
rollover works.
Windows Media Services implements RTSP through the WMS RTSP
Server Control Protocol plug-in. In a default installation of
Windows Media Services, this plug-in is enabled and bound to TCP
port 554.
When using RTSPU, setting the RTP packet size to a small value may
prevent the Windows Media server from streaming. For more
information about unicast packet sizes, see How unicast works.
If a client that supports RTSP attempts to
connect to the Windows Media server using a URL that starts with
mms://, the content will be streamed to the client using RTSP.
Notes