RTP Payload Format for 3rd Generation Partnership Project (3GPP) Timed Text
RFC 4396

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Network Working Group                                             J. Rey
Request for Comments: 4396                                     Y. Matsui
Category: Standards Track                                      Panasonic
                                                           February 2006

                           RTP Payload Format
       for 3rd Generation Partnership Project (3GPP) Timed Text

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 (2006).

Abstract

   This document specifies an RTP payload format for the transmission of
   3GPP (3rd Generation Partnership Project) timed text.  3GPP timed
   text is a time-lined, decorated text media format with defined
   storage in a 3GP file.  Timed Text can be synchronized with
   audio/video contents and used in applications such as captioning,
   titling, and multimedia presentations.  In the following sections,
   the problems of streaming timed text are addressed, and a payload
   format for streaming 3GPP timed text over RTP is specified.

Rey & Matsui                Standards Track                     [Page 1]
RFC 4396          Payload Format for 3GPP Timed Text       February 2006

Table of Contents

   1. Introduction ....................................................3
   2. Motivation, Requirements, and Design Rationale ..................3
      2.1. Motivation .................................................3
      2.2. Basic Components of the 3GPP Timed Text Media Format .......4
      2.3. Requirements ...............................................5
      2.4. Limitations ................................................6
      2.5. Design Rationale ...........................................7
   3. Terminology ....................................................10
   4. RTP Payload Format for 3GPP Timed Text .........................12
      4.1. Payload Header Definitions ................................13
           4.1.1. Common Payload Header Fields .......................15
           4.1.2. TYPE 1 Header ......................................17
           4.1.3. TYPE 2 Header ......................................20
           4.1.4. TYPE 3 Header ......................................23
           4.1.5. TYPE 4 Header ......................................24
           4.1.6. TYPE 5 Header ......................................25
      4.2. Buffering of Sample Descriptions ..........................25
           4.2.1. Dynamic SIDX Wraparound Mechanism ..................26
      4.3. Finding Payload Header Values in 3GP Files ................28
      4.4. Fragmentation of Timed Text Samples .......................31
      4.5. Reassembling Text Samples at the Receiver .................33
      4.6. On Aggregate Payloads .....................................35
      4.7. Payload Examples ..........................................39
      4.8. Relation to RFC 3640 ......................................43
      4.9. Relation to RFC 2793 ......................................44
   5. Resilient Transport ............................................45
   6. Congestion Control .............................................46
   7. Scene Description ..............................................47
      7.1. Text Rendering Position and Composition ...................47
      7.2. SMIL Usage ................................................48
      7.3. Finding Layout Values in a 3GP File .......................48
   8. 3GPP Timed Text Media Type .....................................49
   9. SDP Usage ......................................................53
      9.1. Mapping to SDP ............................................53
      9.2. Parameter Usage in the SDP Offer/Answer Model .............53
           9.2.1. Unicast Usage ......................................54
           9.2.2. Multicast Usage ....................................57
      9.3. Offer/Answer Examples .....................................58
      9.4. Parameter Usage outside of Offer/Answer ...................60
   10. IANA Considerations ...........................................60
   11. Security Considerations .......................................60
   12. References ....................................................61
      12.1. Normative References .....................................61
      12.2. Informative References ...................................61
   13. Basics of the 3GP File Structure ..............................64
   14. Acknowledgements ..............................................65

Rey & Matsui                Standards Track                     [Page 2]