Enhancements for RFC 4103 real-time text mixing are provided in this
document, suitable for a centralized conference model that enables
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 multi-party real-time text
session. The specified mechanism builds on the standard use of the
CSRC list in the RTP packet for source identification. The method
makes use of the same "text/t140" and "text/red" formats as for two-
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 possibility to implement the solution in a wide
range of existing RTP implementations made the RTP-mixer model be
selected to be fully specified in this document.
A capability exchange is specified so that it can be verified that a
mixer and a participant can handle the multi-party coded real-time
text stream using the RTP-mixer method. The capability is indicated
by use of an SDP media attribute "rtt-mixer".
The document updates RFC 4103 "RTP Payload for Text Conversation".
A specification of how a mixer can format text for the case when the
endpoint is not multi-party aware is also provided.
Working Group Summary:
WG Last Call of "RTP-mixer formatting of multi-party Real-time text" was
announced on November 25, 2020:
WGLC concluded on December 9, 2020.
Of the 6 participants responding to the WGLC, 3 supported Advancement to
Proposed Standard, and 3 respondents provided comments, which were addressed
by the author.
There are no existing implementations of the specification.
Document Shepherd is Bernard Aboba. Responsible AD is Murray Kucherawy.