RTP Payload for Text Conversation
RFC 4103
Document | Type |
RFC - Proposed Standard
(June 2005; Errata)
Obsoletes RFC 2793
|
|
---|---|---|---|
Authors | Paul Jones , Gunnar Hellstrom | ||
Last updated | 2018-12-20 | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4103 (Proposed Standard) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Unknown | ||
Telechat date | |||
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 per second or less. In general, only one or a few new characters are expected to be transmitted with each packet. Small blocks of text may be prepared by the user and pasted into the user interface forShow full document text