Real-time text media handling in multi-party conferences
draft-hellstrom-mmusic-multi-party-rtt-00

Document Type Active Internet-Draft (individual)
Last updated 2019-10-31
Replaces draft-hellstrom-text-conference
Stream (None)
Intended RFC status (None)
Formats plain text xml pdf htmlized bibtex
Stream Stream state (No stream defined)
Consensus Boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date
Responsible AD (None)
Send notices to (None)
Internet Engineering Task Force                             G. Hellstrom
Internet-Draft                                                   Omnitor
Intended status: Best Current Practice                  November 1, 2019
Expires: May 4, 2020

        Real-time text media handling in multi-party conferences
               draft-hellstrom-mmusic-multi-party-rtt-00

Abstract

   This memo specifies methods for Real-Time Text (RTT) media handling
   in multi-party calls.  The main solution is to carry Real-Time text
   by the RTP protocol in a time-sampled mode according to RFC 4103.
   The main solution for centralized multi-party handling of real-time
   text is achieved through a media control unit coordinating multiple
   RTP text streams into one RTP session.

   Identification for the streams are provided through the RTCP
   messages.  This mechanism enables the receiving application to
   present the received real-time text medium in different ways
   according to user preferences.  Some presentation related features
   are also described explaining suitable variations of transmission and
   presentation of text.

   Call control features are described for the SIP environment.  A
   number of alternative methods for providing the multi-party
   negotiation, transmission and presentation are discussed and a
   recommendation for the main one is provided.  Two alternative methods
   using a single RTP stream and source identification inline in the
   text stream are also described, one of them being provided as a lower
   functionality fallback method for endpoints with no multi-party
   awareness for RTT.

   Brief information is also provided for multi-party RTT in the WebRTC
   environment.

   EDITOR NOTE: A number of alternatives are specified for discussion.
   A decision is needed which alternatives are preferred and then how
   the preferred alternatives shall be emphasized.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute

Hellstrom                  Expires May 4, 2020                  [Page 1]
Internet-Draft     Real-time text multi-party handling     November 2019

   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 4, 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  Centralized conference model  . . . . . . . . . . . . . . . .   4
   3.  Requirements on multi-party RTT . . . . . . . . . . . . . . .   5
   4.  Coordination of text RTP streams  . . . . . . . . . . . . . .   6
     4.1.  RTP Translator sending one RTT stream per participant . .   6
     4.2.  RTP Mixer indicating participants in CSRC . . . . . . . .   7
     4.3.  RTP Mixer indicating participants by a control code in
           the stream  . . . . . . . . . . . . . . . . . . . . . . .   8
     4.4.  Mesh of RTP endpoints . . . . . . . . . . . . . . . . . .   9
     4.5.  Multiple RTP sessions, one for each participant . . . . .  10
     4.6.  Mixing for conference-unaware user agents . . . . . . . .  10
   5.  RTT bridging in WebRTC  . . . . . . . . . . . . . . . . . . .  12
     5.1.  RTT bridging in WebRTC with one data channel per source .  12
     5.2.  RTT bridging in WebRTC with one common data channel . . .  12
   6.  Preferred multi-party RTT transport method  . . . . . . . . .  13
   7.  Session control of multi-party RTT sessions . . . . . . . . .  14
     7.1.  Implicit RTT multi-party capability indication  . . . . .  15
     7.2.  RTT multi-party capability declared by SIP media-tags . .  16
     7.3.  SDP media attribute for RTT multi-party capability
           indication  . . . . . . . . . . . . . . . . . . . . . . .  17
Show full document text