datatracker.ietf.org
Sign in
Version 5.6.2.p5, 2014-08-04
Report a bug

RTP Payload for Text Conversation
RFC 4103

Document type: RFC - Proposed Standard (June 2005; Errata)
Obsoletes RFC 2793
Document stream: IETF
Last updated: 2013-03-02
Other versions: plain text, pdf, html

IETF State: (None)
Consensus: Unknown
Document shepherd: No shepherd assigned

IESG State: RFC 4103 (Proposed Standard)
Responsible AD: Allison Mankin
Send notices to: csp@csperkins.org, magnus.westerlund@ericsson.com

Network Working Group                                      G. Hellstrom
Request for Comments: 4103                                   Omnitor AB
Obsoletes: 2793                                                P. Jones
Category: Standards Track                           Cisco Systems, Inc.
                                                              June 2005

                   RTP Payload for Text Conversation

Status of This Memo

   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 "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).

Abstract

   This memo obsoletes RFC 2793; it describes how to carry real-time
   text conversation session contents in RTP packets.  Text conversation
   session contents are specified in ITU-T Recommendation T.140.

   One payload format is described for transmitting text on a separate
   RTP session dedicated for the transmission of text.

   This RTP payload description recommends a method to include redundant
   text from already transmitted packets in order to reduce the risk of
   text loss caused by packet loss.

Hellstrom & Jones           Standards Track                     [Page 1]
RFC 4103           RTP Payload for Text Conversation           June 2005

Table of Contents

   1.  Introduction ...................................................3
   2.  Conventions Used in This Document ..............................4
   3.  Usage of RTP ...................................................4
       3.1. Motivations and Rationale .................................4
       3.2. Payload Format for Transmission of text/t140 Data .........4
       3.3. The "T140block" ...........................................5
       3.4. Synchronization of Text with Other Media ..................5
       3.5. RTP Packet Header .........................................5
   4.  Protection against Loss of Data ................................6
       4.1. Payload Format When Using Redundancy ......................6
       4.2. Using Redundancy with the text/t140 Format ................7
   5.  Recommended Procedure ..........................................8
       5.1. Recommended Basic Procedure ...............................8
       5.2. Transmission before and after "Idle Periods" ..............8
       5.3. Detection of Lost Text Packets ............................9
       5.4. Compensation for Packets Out of Order ....................10
   6.  Parameter for Character Transmission Rate .....................10
   7.  Examples ......................................................11
       7.1. RTP Packetization Examples for the text/t140 Format ......11
       7.2. SDP Examples .............................................13
   8.  Security Considerations .......................................14
       8.1. Confidentiality ..........................................14
       8.2. Integrity ................................................14
       8.3. Source Authentication ....................................14
   9.  Congestion Considerations .....................................14
   10. IANA Considerations ...........................................16
       10.1. Registration of MIME Media Type text/t140 ...............16
       10.2. SDP Mapping of MIME Parameters ..........................17
       10.3. Offer/Answer Consideration ..............................17
   11. Acknowledgements ..............................................18
   12. Normative References ..........................................18
   13. Informative References ........................................19

Hellstrom & Jones           Standards Track                     [Page 2]
RFC 4103           RTP Payload for Text Conversation           June 2005

1.  Introduction

   This document defines a payload type for carrying text conversation
   session contents in RTP [2] packets.  Text conversation session
   contents are specified in ITU-T Recommendation T.140 [1].  Text
   conversation is used alone or in connection with other conversational
   facilities, such as video and voice, to form multimedia conversation
   services.  Text in multimedia conversation sessions is sent
   character-by-character as soon as it is available, or with a small
   delay for buffering.

   The text is intended to be entered by human users from a keyboard,
   handwriting recognition, voice recognition or any other input method.
   The rate of character entry is usually at a level of a few characters

[include full document text]