Indicating source of multi-party Real-time text
draft-hellstrom-avtcore-multi-party-rtt-source-00

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Document Type Active Internet-Draft (individual)
Author Gunnar Hellstrom 
Last updated 2020-02-26
Replaced by draft-ietf-avtcore-multi-party-rtt-mix
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Network Working Group                                      GH. Hellstrom
Internet-Draft                                                   Omnitor
Updates: RFC 4102, RFC 4103 (if                        February 26, 2020
         approved)
Intended status: Standards Track
Expires: August 29, 2020

            Indicating source of multi-party Real-time text
           draft-hellstrom-avtcore-multi-party-rtt-source-00

Abstract

   Real-time text mixers need to identify the source of each transmitted
   text chunk so that it can be presented in suitable grouping with
   other text from the same source.  An enhancement for RFC 4103 real-
   time text is provided, suitable for a centralized conference model
   that enables source identification, and provision of text mixers and
   conference-enabled participants.  The mechanism builds on use of the
   CSRC list in the RTP packet.  A capability exchange is specified so
   that it can be verified that a participant can handle the multi-party
   coded real-time text stream.  The capability is indicated by a format
   parameter "rtp-mix".

Status of This Memo

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   This Internet-Draft will expire on August 29, 2020.

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   Copyright (c) 2020 IETF Trust and the persons identified as the
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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents

Hellstrom                Expires August 29, 2020                [Page 1]
Internet-Draft     Indicate source of multi-party RTT      February 2020

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Nomenclature  . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Intended application  . . . . . . . . . . . . . . . . . . . .   3
   4.  Use of fields in the RTP packets  . . . . . . . . . . . . . .   3
   5.  Actions at transmission by a mixer  . . . . . . . . . . . . .   4
   6.  Actions at reception  . . . . . . . . . . . . . . . . . . . .   5
   7.  RTCP considerations . . . . . . . . . . . . . . . . . . . . .   6
   8.  Chained operation . . . . . . . . . . . . . . . . . . . . . .   6
   9.  Use with SIP centralized conferencing framework . . . . . . .   6
   10. Usage without redundancy  . . . . . . . . . . . . . . . . . .   7
   11. SDP considerations  . . . . . . . . . . . . . . . . . . . . .   7
   12. Capability negotiation  . . . . . . . . . . . . . . . . . . .   7
   13. Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
   14. Performance considerations  . . . . . . . . . . . . . . . . .   9
   15. Presentation level considerations . . . . . . . . . . . . . .   9
   16. Congestion considerations . . . . . . . . . . . . . . . . . .  10
   17. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  10
   18. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
     18.1.  Addition of the rtp-mix fmtp-parameter to the text/red
            format . . . . . . . . . . . . . . . . . . . . . . . . .  10
     18.2.  Addition of the rtp-mix fmtp-parameter to the text/t140
            format . . . . . . . . . . . . . . . . . . . . . . . . .  11
   19. Security Considerations . . . . . . . . . . . . . . . . . . .  11
   20. References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     20.1.  Normative References . . . . . . . . . . . . . . . . . .  12
     20.2.  Informative References . . . . . . . . . . . . . . . . .  12
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   RFC 4103[RFC4103] specifies use of RFC 3550 RTP[RFC3550] for
   transmission of RTT and the text/t140 format.  It also specifies a
   redundancy scheme text/red for increased robustness.  RFC 4102
   [RFC4102] registers the text/red format.  The redundancy scheme
   enables very efficient transmission of redundant text in packets
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