RFC 9071 on RTP-Mixer Formatting of Multiparty Real-Time Text

rfc-editor@rfc-editor.org Tue, 06 July 2021 23:47 UTC

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A new Request for Comments is now available in online RFC libraries.

        RFC 9071

        Title:      RTP-Mixer Formatting of Multiparty Real-Time 
        Author:     G. Hellström
        Status:     Standards Track
        Stream:     IETF
        Date:       July 2021
        Mailbox:    gunnar.hellstrom@ghaccess.se
        Pages:      35
        Updates:    RFC 4103

        I-D Tag:    draft-ietf-avtcore-multi-party-rtt-mix-20.txt

        URL:        https://www.rfc-editor.org/info/rfc9071

        DOI:        10.17487/RFC9071

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 two-party

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, "rtt-mixer". 

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.

This document is a product of the Audio/Video Transport Core Maintenance Working Group of the IETF.

This is now a Proposed Standard.

STANDARDS TRACK: This document specifies an Internet Standards Track
protocol for the Internet community, and requests discussion and suggestions
for improvements.  Please refer to the current edition of the Official
Internet Protocol Standards (https://www.rfc-editor.org/standards) for the 
standardization state and status of this protocol.  Distribution of this 
memo is unlimited.

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