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author | Thomas Voss <mail@thomasvoss.com> | 2024-11-27 20:54:24 +0100 |
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committer | Thomas Voss <mail@thomasvoss.com> | 2024-11-27 20:54:24 +0100 |
commit | 4bfd864f10b68b71482b35c818559068ef8d5797 (patch) | |
tree | e3989f47a7994642eb325063d46e8f08ffa681dc /doc/rfc/rfc4102.txt | |
parent | ea76e11061bda059ae9f9ad130a9895cc85607db (diff) |
doc: Add RFC documents
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diff --git a/doc/rfc/rfc4102.txt b/doc/rfc/rfc4102.txt new file mode 100644 index 0000000..b5880f1 --- /dev/null +++ b/doc/rfc/rfc4102.txt @@ -0,0 +1,339 @@ + + + + + + +Network Working Group P. Jones +Request for Comments: 4102 Cisco Systems, Inc. +Category: Standards Track June 2005 + + + Registration of the text/red MIME Sub-Type + +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 document defines the text/red MIME sub-type. "Red" is short for + redundant. The actual RTP packetization for this MIME type is + specified in RFC 2198. + +1. Introduction + + Text is an important component of any multimedia communication + system. Like audio, the transport of text can benefit from the use + of redundancy in order to improve reliability and end-user + experience. + + RFC 2198 [1] defines an RTP [2] payload format for redundant audio + data. The format defined in that document is quite suitable for + providing redundancy for text, as well as audio. + + RFC 4103 [8] specifies one usage of RFC 2198 and the text/red MIME + type for the transport of redundant text data. + + This memo provides the MIME sub-type registration information for + text/red. While this document focuses on the use of this MIME sub- + type in SDP [5], the application of this MIME sub-type is not + restricted to SDP. + + + + + + + + +Jones Standards Track [Page 1] + +RFC 4102 text/red MIME Sub-Type June 2005 + + +2. Conventions Used in This Document + + The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", + "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this + document are to be interpreted as described in RFC 2119 [3]. + +3. IANA Considerations + + One new MIME sub-type has been registered by the IANA, as described + below: + + MIME media type name: text + + MIME subtype name: RED + + Required parameters: + rate: the RTP clock rate of the payload carried within the RTP + packet. Typically, this rate is 1000, but other rates MAY be + specified. This parameter MUST be set equal to the clock rate of + the text payload format carried as the primary encoding. + + pt: a comma-separated ordered list of RTP payload types + enumerating the primary, secondary, etc., in accordance with RFC + 2198. Because comma is a special character, the list MUST be a + quoted-string (enclosed in double quotes). For static payload + types, each list element is simply the type number. For dynamic + payload types, each list element is a mapping of the dynamic + payload type number to an embedded MIME content-type specification + for the payload format corresponding to the dynamic payload type. + The format of the mapping is: + + dynamic-payload-type "=" content-type + + If the content-type string includes a comma, then the content- + type string MUST be a quoted-string. If the content-type string + does not include a comma, it MAY still be quoted. Because it is + part of the list, which must itself be a quoted-string, the + quotation marks MUST be quoted with backslash quoting as specified + in RFC 2045 [4]. If the content-type string itself contains a + quoted-string, then the requirement for backslash quoting is + recursively applied. + + Optional parameters: ptime, maxptime (these attributes are originally + defined in RFC 2327 [5] and RFC 3267 [6], respectively) + + Restrictions on Usage: + This type is defined only for transfer via RTP. + It shall not be defined for a storage format. + + + +Jones Standards Track [Page 2] + +RFC 4102 text/red MIME Sub-Type June 2005 + + + Encoding considerations: + See restrictions on Usage above; this section is included per + the requirements in RFC 3555 [7]. + + Security considerations: Refer to section 5 of RFC 4102. + + Interoperability considerations: none + + Published specification: RFC 2198 + + Applications which use this media type: + Text streaming and conferencing tools. + + Additional information: none + + Person & email address to contact for further information: + Paul E. Jones + E-mail: paulej@packetizer.com + + Intended usage: COMMON + + Author: + Paul E. Jones + paulej@packetizer.com + + Change Controller: + AVT Working Group delegated from the IESG + +4. Mapping to SDP Parameters + + The information carried in the MIME media type specification has a + specific mapping to fields in the Session Description Protocol (SDP) + [5], which is commonly used to describe RTP sessions. When SDP is + used to specify sessions employing the RFC 2198 in a text session, + the mapping is as follows: + + - The MIME type ("text") goes in SDP "m=" as the media name. + + - The value of the parameter "rate" goes in SDP "a=rtpmap". + + - The MIME subtype (RED) goes in SDP "a=rtpmap" as the encoding + name. + + - The parameters "ptime" and "maxptime" go in the SDP "a=ptime" and + "a=maxptime" attributes, respectively. + + + + + + +Jones Standards Track [Page 3] + +RFC 4102 text/red MIME Sub-Type June 2005 + + + - The pt parameter is mapped to an a=fmtp attribute by eliminating + the parameter name (pt) and changing the commas to slashes. For + example, 'pt="101,102"' maps to 'a=fmtp:99 101/102', where = '99' + is the payload type of the redundancy frames. Note that the + single quote marks (') used in this example are not present in the + actual message encoding, but are present here only for + readability. The level of redundancy is shown by the number of + elements in the payload type list. + + Any dynamic payload type in the list MUST be represented by its + payload type number and not by its content-type. The mapping of + payload types to the content-type is done using the normal SDP + procedures with "a=rtpmap". + + An example of SDP is: + + m=text 11000 RTP/AVP 98 100 + a=rtpmap:98 t140/1000 + a=rtpmap:100 red/1000 + a=fmtp:100 98/98 + + For each redundancy payload type defined, the ordering of the primary + and redundancy encoding(s) is fixed. If more than one combination of + primary and redundancy encoding(s) is desired, multiple redundancy + payload types needs to be defined. + +5. Security Considerations + + The security considerations listed in RFC 2198 apply. Further, it + should be understood that text data, perhaps even more so than audio + data, is susceptible to unwanted modification that may lead to + undesired results. To prevent modification of the primary, + secondary, or header information, payload integrity protection over + at least the complete RTP packet is RECOMMENDED, for example using + SRTP [9]. + + + + + + + + + + + + + + + + +Jones Standards Track [Page 4] + +RFC 4102 text/red MIME Sub-Type June 2005 + + +6. Normative References + + [1] Perkins, C., Kouvelas, I., Hodson, O., Hardman, V., Handley, M., + Bolot, J., Vega-Garcia, A., and S. Fosse-Parisis, "RTP Payload + for Redundant Audio Data", RFC 2198, September 1997. + + [2] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, + "RTP: A Transport Protocol for Real-Time Applications", STD 64, + RFC 3550, July 2003. + + [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement + Levels", BCP 14, RFC 2119, March 1997. + + [4] Freed, N. and N. Borenstein, "Multipurpose Internet Mail + Extensions (MIME) Part One: Format of Internet Message Bodies", + RFC 2045, November 1996. + + [5] Handley, M., Jackson, V., "SDP: Session Description Protocol", + RFC 2327, April 1998. + + [6] Sjoberg, J., Westerlund, M., Lakaniemi, A., and Q. Xie, "Real- + Time Transport Protocol (RTP) Payload Format and File Storage + Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate + Wideband (AMR-WB) Audio Codecs", RFC 3267, June 2002. + + [7] Casner, S. and P. Hoschka, "MIME Type Registration of RTP Payload + Formats", RFC 3555, July 2003. + +7. Informative References + + [8] Hellstrom, G. and P. Jones, "RTP Payload for Text Conversation", + RFC 4103, June 2005. + + [9] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. + Norrman, "The Secure Real-time Transport Protocol (SRTP)", RFC + 3711, March 2004. + +Author's Address + + Paul E. Jones + Cisco Systems, Inc. + 7025 Kit Creek Rd. + Research Triangle Park, NC 27709, USA + + Phone: +1 919 392 6948 + EMail: paulej@packetizer.com + + + + + +Jones Standards Track [Page 5] + +RFC 4102 text/red MIME Sub-Type June 2005 + + +Full Copyright Statement + + Copyright (C) The Internet Society (2005). + + This document is subject to the rights, licenses and restrictions + contained in BCP 78, and except as set forth therein, the authors + retain all their rights. + + This document and the information contained herein are provided on an + "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS + OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET + ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, + INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE + INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED + WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. + +Intellectual Property + + The IETF takes no position regarding the validity or scope of any + Intellectual Property Rights or other rights that might be claimed to + pertain to the implementation or use of the technology described in + this document or the extent to which any license under such rights + might or might not be available; nor does it represent that it has + made any independent effort to identify any such rights. Information + on the procedures with respect to rights in RFC documents can be + found in BCP 78 and BCP 79. + + Copies of IPR disclosures made to the IETF Secretariat and any + assurances of licenses to be made available, or the result of an + attempt made to obtain a general license or permission for the use of + such proprietary rights by implementers or users of this + specification can be obtained from the IETF on-line IPR repository at + http://www.ietf.org/ipr. + + The IETF invites any interested party to bring to its attention any + copyrights, patents or patent applications, or other proprietary + rights that may cover technology that may be required to implement + this standard. Please address the information to the IETF at ietf- + ipr@ietf.org. + +Acknowledgement + + Funding for the RFC Editor function is currently provided by the + Internet Society. + + + + + + + +Jones Standards Track [Page 6] + |