RTP Audio Video Profiles

The use of profiles enables RTP to be an extremely general media transport protocol. The current audio video profiles defined by RFC 3551 are listed inTable. The profile document makes the following specifications for RTP:

* UDP is used for underlying transport;
* RTP port numbers are always even, the corresponding RTCP port number is the next highest port, always an odd number;
* No header extensions are used.

RTP/AVP Audio and Video Payload Types

For each of the profiles listed in Table, the profile document lists details of the codec, or a reference for the details is provided. Payloads in therange 96–127 can be defined dynamically during a session. The minimum payload support is defined as 0 (PCMU) and 5 (DVI4). The document recommends dynamically assigned port numbers, although 5004 and 5005 have been registered for use of the profile and can be used instead. The standard alsodescribes the process of registering new payload types with IANA. There are other references for a tutorial description of many of these audio codecs and video codecs.
The information in the first three columns of Table is also containedin the SDP a=rtp