Standards Track A. Rao Netscap - RFC Editor

RFC 2326 Real Time Streaming Protocol April 1998of RFC 1123 \cite{rfc1123}>port = *DIGITabs_path is defined in [H3.2.1].Note that fragment and query identifiers do not have a well-definedmeaning at this time, with the interpretation left to the RTSPserver.The scheme rtsp requires that commands are issued via a reliableprotocol (within the Internet, TCP), while the scheme rtspu identifiesan unreliable protocol (within the Internet, UDP).If the port is empty or not given, port 554 is assumed. The semanticsare that the identified resource can be controlled by RTSP at theserver listening for TCP (scheme "rtsp") connections or UDP (scheme"rtspu") packets on that port of host, and the Request-URI for theresource is rtsp_URL.The use of IP addresses in URLs SHOULD be avoided whenever possible(see RFC 1924 [19]).A presentation or a stream is identified by a textual mediaidentifier, using the character set and escape conventions [H3.2] ofURLs (RFC 1738 [20]). URLs may refer to a stream or an aggregate ofstreams, i.e., a presentation. Accordingly, requests described inSection 10 can apply to either the whole presentation or an individualstream within the presentation. Note that some request methods canonly be applied to streams, not presentations and vice versa.For example, the RTSP URL:rtsp://media.example.com:554/twister/audiotrackidentifies the audio stream within the presentation "twister", whichcan be controlled via RTSP requests issued over a TCP connection toport 554 of host media.example.com.Also, the RTSP URL:rtsp://media.example.com:554/twisteridentifies the presentation "twister", which may be composed ofaudio and video streams.This does not imply a standard way to reference streams in URLs.The presentation description defines the hierarchical relationshipsin the presentation and the URLs for the individual streams. Apresentation description may name a stream "a.mov" and the wholepresentation "b.mov".Schulzrinne, et. al. Standards Track [Page 15]