RTP translators/mixers

Translator	changes transport (e.g., IPv4 to IPv6) or changes media coding (i.e., transcoding)
Mixer	combines multiple streams to form a combined stream

Connect two or more transport-level “clouds”, each cloud is defined by a common network and transport protocol (e.g., IP/UDP), multicast address or pair of unicast addresses, and transport level destination port.

To avoid creating a loop the following rules must be observed:

“Each of the clouds connected by translators and mixers participating in one RTP session either must be distinct from all the others in at least one of these parameters (protocol, address, port), or must be isolated at the network level from the others.

A derivative of the first rule is that there must not be multiple translators or mixers connected in parallel unless by some arrangement they partition the set of sources to be forwarded.”

From §7.1 General Description of RFC 1889

Slide Notes

[RFC 1889] Audio-Video Transport Working Group, H. Schulzrinne, S. Casner, R. Frederick, and V. Jacobson, ‘RTP: A Transport Protocol for Real-Time Applications’, Internet Request for Comments, vol. RFC 1889 (Proposed Standard), Jan. 1996 [Online]. Available: http://www.rfc-editor.org/rfc/rfc1889.txt Links to an external site.

Transcript

[slide104] So we talked about these translators and mixers. You can, of course, put them together to form clouds to do arbitrary levels of mixing and translation. But as we said, it's very important. Never, ever put an audio or a video together with itself.