AVT Working Group
Internet Draft P. Jones
<draft-jones-avt-text-red-00.txt> Cisco Systems, Inc.
Expires: May 2004 November 2003
Registration of the text/red MIME Sub-Type
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC 2026.
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Abstract
This document defines the text/red MIME sub-type. The packetization
and usage of this MIME type, which is intended for use within SDP, is
specified within RFC 2198 and RFC 2793, respectively.
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 defines a payload format for audio data. The format defined
in that document is quite suitable for providing redundancy for text,
as well as audio.
RFC 2793 [1] specifies the use of RFC 2198 for the transport of
redundant text data.
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This memo provides the MIME sub-type registration information.
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 [4].
3. IANA Considerations
One new MIME sub-type is to be registered, as described below:
MIME media type name: text
MIME subtype name: RED
Required parameters:
pt: a comma-separated list of RTP payload types. 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.
Since it is part of the list which must itself be a quoted-
string, that means the quotation marks MUST be quoted with
backslash quoting as specified in RFC 2045 [5]. If the content-
type string itself contains a quoted-string, then the
requirement for backslash quoting is recursively applied. To
specify the text/RED payload format in SDP, 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'.
Optional parameters: ptime, maxptime
Encoding considerations:
This type is only defined for transfer via RTP [3].
Security considerations: Refer to section 4.
Interoperability considerations: none
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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 / Change controller:
Paul E. Jones | IETF avt WG
paulej@packetizer.com |
4. 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.
5. Normative References
[1] Hellstrom, G., "RTP Payload for Text Conversation”, RFC 2793,
May 2000.
[2] Perkins, C., et al., "RTP Payload for Redundant Audio Data", RFC
2198, September 1997.
[3] Schulzrinne, et al., "RTP: A Transport Protocol for Real-Time
Applications", RFC 3550, July 2003.
[4] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", RFC 2119, March 1997.
[5] Freed, N., Borenstein, N., "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message Bodies",
RFC 2045, November 1996.
6. Author's Address
Paul E. Jones
Cisco Systems, Inc.
7025 Kit Creek Rd.
Research Triangle Park, NC 27709
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Phone: +1 919 392 6948
Email: paulej@packetizer.com
7. Intellectual Property Right Considerations
The IETF takes no position regarding the validity or scope of any
intellectual property 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; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication 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 implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
8. Full Copyright Statement
Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
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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.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
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