Real-Time Transport Protocol (RTP) Payload for Text Conversation Interleaved in an Audio Stream
RFC 4351
Document | Type | RFC - Historic (January 2006; No errata) | |
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Authors | Paul Jones , Gunnar Hellstrom | ||
Last updated | 2018-12-20 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 4351 (Historic) | |
Action Holders |
(None)
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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: 4351 Omnitor AB Category: Historic P. Jones Cisco Systems, Inc. January 2006 Real-Time Transport Protocol (RTP) Payload for Text Conversation Interleaved in an Audio Stream Status of This Memo This memo defines a Historic Document for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This memo 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 audio and text data within a single RTP session. 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 Historic [Page 1] RFC 4351 RTP Payload for Text in an Audio Stream January 2006 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 audio/t140c Data ........4 3.3. The "T140block" ............................................5 3.4. Synchronization of Text with Other Media ...................5 3.5. Synchronization Considerations for the audio/t140c Format ..5 3.6. RTP Packet Header ..........................................6 4. Protection against Loss of Data .................................7 4.1. Payload Format When Using Redundancy .......................7 4.2. Using Redundancy with the audio/t140c Format ...............8 5. Recommended Procedure ...........................................8 5.1. Recommended Basic Procedure ................................8 5.2. Transmission before and after "Idle Periods" ...............9 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 audio/t140c Format .....11 7.2. SDP Examples ..............................................12 8. Security Considerations ........................................13 8.1. Confidentiality ...........................................13 8.2. Integrity .................................................13 8.3. Source Authentication .....................................13 9. Congestion Considerations ......................................14 10. IANA Considerations ...........................................15 10.1. Registration of MIME Media Type audio/t140c ..............15 10.2. SDP Mapping of MIME Parameters ...........................16 10.3. Offer/Answer Consideration ...............................17 11. Acknowledgements ..............................................17 12. Normative References ..........................................17 13. Informative References ........................................18 Hellstrom & Jones Historic [Page 2] RFC 4351 RTP Payload for Text in an Audio Stream January 2006 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 to 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 for transmission during the conversation, occasionallyShow full document text