IETF - RFC 9071
RTP-Mixer Formatting of Multiparty Real-Time Text
Organization: | IETF |
Publication Date: | 1 July 2021 |
Status: | active |
Page Count: | 35 |
scope:
Abstract
This document provides enhancements of real-time text (as specified in RFC 4103) suitable for mixing in a centralized conference model, enabling source identification and rapidly interleaved transmission of text from different sources. The intended use is for real-time text mixers and participant endpoints capable of providing an efficient presentation or other treatment of a multiparty real-time text session. The specified mechanism builds on the standard use of the Contributing Source (CSRC) list in the Real-time Transport Protocol (RTP) packet for source identification. The method makes use of the same "text/t140" and "text/red" formats as for twoparty sessions.
Solutions using multiple RTP streams in the same RTP session are briefly mentioned, as they could have some benefits over the RTP-mixer model. The RTP-mixer model was selected to be used for the fully specified solution in this document because it can be applied to a wide range of existing RTP implementations.
A capability exchange is specified so that it can be verified that a mixer and a participant can handle the multiparty-coded real-time text stream using the RTP-mixer method. The capability is indicated by the use of a Session Description Protocol (SDP) (RFC 8866) media attribute, "rttmixer".
This document updates RFC 4103 ("RTP Payload for Text Conversation").
A specification for how a mixer can format text for the case when the endpoint is not multiparty aware is also provided.
Document History
