Editing Real-time Transport Protocol (section)

==Profiles and payload formats==
{{main|RTP payload formats}}

RTP is designed to carry a multitude of multimedia formats, which permits the development of new formats without revising the RTP standard. To this end, the information required by a specific application of the protocol is not included in the generic RTP header. For each class of application (e.g., audio, video), RTP defines a ''profile'' and associated ''payload formats''.<ref name="Peterson_430">{{Cite book| author=Larry L. Peterson | title=Computer Networks | page= [https://books.google.com/books?id=zGVVuO-6w3IC&pg=PA430 430] | publisher=Morgan Kaufmann | year=2007 | isbn=978-1-55860-832-0}}</ref> Every instantiation of RTP in a particular application requires a profile and payload format specifications.<ref name=RFC3550>{{IETF RFC|3550}}</ref>{{rp|71}}

The profile defines the codecs used to encode the payload data and their mapping to payload format codes in the protocol field ''Payload Type'' (PT) of the RTP header. Each profile is accompanied by several payload format specifications, each of which describes the transport of particular encoded data.<ref name="Perkins_55"/> Examples of audio payload formats are [[G.711]], [[G.723]], [[G.726]], [[G.729]], [[GSM]], [[QCELP]], [[MP3]], and [[DTMF]], and examples of video payloads are [[H.261]], [[H.263]], [[H.264]], [[H.265]] and [[MPEG-1]]/[[MPEG-2]].<ref name="perkins_60">{{harvnb|Perkins|2003|p=60}}</ref> The mapping of [[MPEG-4]] audio/video streams to RTP packets is specified in {{IETF RFC|3016}}, and H.263 video payloads are described in {{IETF RFC|2429}}.<ref name=Chou2007>{{Cite book|last=Chou|first=Philip A. |author2=Mihaela van der Schaar |title=Multimedia over IP and wireless networks|publisher=Academic Press|year=2007|pages=[https://books.google.com/books?id=zeLFs3GD0QQC&pg=PA514 514]|isbn=978-0-12-088480-3}}</ref>

Examples of RTP profiles include:
* The ''RTP profile for Audio and video conferences with minimal control'' ({{IETF RFC|3551}}) defines a set of static payload type assignments, and a dynamic mechanism for mapping between a payload format, and a PT value using [[Session Description Protocol]] (SDP).
* The [[Secure Real-time Transport Protocol]] (SRTP) ({{IETF RFC|3711}}) defines an RTP profile that provides [[cryptographic]] services for the transfer of payload data.<ref>{{harvnb|Perkins|2003|p=367}}</ref>
* The experimental ''Control Data Profile for RTP'' (RTP/CDP) for [[machine-to-machine]] communications.<ref name=Breese2010>{{Cite book|last=Breese|first=Finley|title=Serial Communication over RTP/CDP|publisher=BoD - Books on Demand|year=2010|pages=[https://books.google.com/books?id=t18ehd_vM6wC&lpg=PP1&pg=PA9]|isbn=978-3-8391-8460-8}}</ref>