RFC3839
Network Working Group R. Castagno Request for Comments: 3839 Nokia Mobile Phones Category: Standards Track D. Singer
Apple Computer, Inc.
July 2004
MIME Type Registrations for 3rd Generation Partnership Project (3GPP) Multimedia files
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 (2004).
Abstract
This document serves to register and document the standard MIME types associated with the 3GPP multimedia file format, which is part of the family based on the ISO Media File Format.
Contents
Introduction
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 BCP 14, RFC 2119 RFC2119.
The third-generation partnership project (3GPP) for third-generation cellular telephony has defined a standard file format to contain audio/visual sequences which may be downloaded to cellular phones [3GPP]. At the time of writing, the 3GPP file format (3GP) can contain H.263 or MPEG-4 video, and AMR Narrow-band speech, AMR wide- band speech, or AAC audio, and 3GPP timed text.
Within the file, as with all files in the 'ISO' family, there is an intrinsic file-type box, which identifies those specifications to which the file complies, and which players (possibly compliant with only one specification) are permitted by the content author to play the file. This identification is through four-letter 'brands'.
Files identified by the MIME [MIME1] type defined here MUST contain a brand defined in a standard issued by 3GPP that can apply to 3GPP files, in their compatible brands list.
The MIME types defined here are needed to correctly identify such files when they are served over HTTP, included in multi-part documents, or used in other places where MIME types are used.
Security Considerations
The 3GPP file format may contain audio, video, and displayable text data. There is currently no provision for 'active' elements (such as scripts) of any kind.
Clearly it is possible to author malicious files which attempt to call for an excessively large picture size, high sampling-rate audio etc. However, clients can and usually do protect themselves against this kind of attack.
It should be noted that selected metadata fields may encompass information partly intended to protect the media against unauthorized use or distribution. In this case, the intention is that alteration or removal of the data in the field would be treated as an offense under national agreements based on World Intellectual Property Organization (WIPO) treaties.
3GPP files have an extensible structure, so that it is theoretically possible that metadata fields or media formats could be defined in the future which could be used to induce particular actions on the part of the recipient, thus presenting additional security risks. However, this type of capability is currently not supported in the referenced specification.
There is no current provision in the standards for encryption, signing, or authentication of these file formats.
MIME Types
This registration applies to all files defined as using the '3GP' file format and identified with a suitable brand in a 3GPP specification. The usual file suffix for all these files is ".3gp".
Files with audio but no video
The type "audio/3gpp" may be used for files containing audio but no visual presentation (neither video nor timed text, for example).
To: [email protected] Subject: Registration of Standard MIME media type audio/3gpp
MIME media type name: audio MIME subtype name: 3gpp Required parameters: none Optional parameters: none
Ongoing work related to this
registration may introduce new
optional parameters. One example
area of effort may introduce a
parameter that would allow for
codecs in use within the MIME type
to be asserted and determined
without examination of the file.
Those with interests in the area
should monitor registrations for
updates.
Encoding considerations: files are binary and should be
transmitted in a suitable encoding
without CR/LF conversion, 7-bit
stripping etc.; base64 is a suitable
encoding. Note that this MIME type
is used only for files; separate
types are used for real-time
transfer, such as for the RTP
payload format for AMR audio
RFC3267.
Security considerations: see the security considerations
section in RFC 3839
Interoperability considerations: The 3GPP organization has defined the
specification, interoperability, and
conformance, and conducts regular
interoperability testing.
Published specification: 3GPP 26.234, Release 5; 3GPP 26.244,
Release 6 or later. 3GPP
specifications are publicly
accessible at the 3GPP web site,
www.3gpp.org.
Applications which use this media type: Multi-media Additional information: The type "audio/3gpp" MAY be used for
files containing audio but no visual
presentation. Files served under
this type MUST NOT contain any
visual material. (Note that 3GPP
timed text is visually presented
and is considered to be visual
material).
Magic number(s): None. However, the file-type box
must occur first in the file, and
MUST contain a 3GPP brand in its
compatible brands list.
File extension(s): 3gp and 3gpp are both declared at
http://www.nist.gov/nics/; 3gp is preferred
Macintosh File Type Code(s): '3gpp' Person & email address to contact for further information:
Nokia MIME manager, [email protected]
Intended usage: COMMON Change controller: 3GPP
Any files
The type "video/3gpp" is valid for all files. It is valid to serve an audio-only file as "video/3gpp".
To: [email protected] Subject: Registration of Standard MIME media type video/3gpp
MIME media type name: video MIME subtype name: 3gpp Required parameters: none Optional parameters: none Encoding considerations: files are binary and should be
transmitted in a suitable encoding
without CR/LF conversion, 7-bit
stripping etc.; base64 is a suitable
encoding. Note that this MIME type
is used only for files; separate
types are used for real-time
transfer, such as for the RTP
payload formats for H.263
RFC2429 and AMR audio
RFC3267.
Security considerations: see the security considerations
section in RFC 3839
Interoperability considerations: The 3GPP organization has defined the
specification, interoperability, and
conformance, and conducts regular
interoperability testing.
Published specification: 3GPP 26.234, Release 5; 3GPP 26.244,
Release 6 or later. 3GPP
specifications are publicly
accessible at the 3GPP web site,
www.3gpp.org.
Applications which use this media type: Multi-media
Additional information: Magic number(s): None. However, the file-type box
must occur first in the file, and
MUST contain a 3GPP brand in its
compatible brands list.
File extension(s): 3gp and 3gpp are both declared at
http://www.nist.gov/nics/; 3gp is preferred
Macintosh File Type Code(s): '3gpp' Person & email address to contact for further information:
Nokia MIME manager, [email protected]
Intended usage: COMMON Change controller: 3GPP
IANA Considerations
This document registers the MIME types audio/3gpp and video/3gpp, defined above.
Acknowledgments
The review of the 3GPP SA4 committee is gratefully acknowledged, in particular Per Frojdh. The chairs of the AVT working group, in particular Colin Perkins, have provided both excellent guidance and feedback, for which the authors are grateful.
References
Normative References
[3GPP] Published specifications in releases 5 and 6: Release 5:
3GPP TS 26.234: Transparent end-to-end packet switched
streaming service (PSS); Protocols and codecs. Release 6:
3GPP TS 26.244: Transparent end-to-end packet switched
streaming service (PSS); 3GPP file format (3GP)
[MIME1] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message
Bodies", RFC 2045, November 1996.
RFC2119 Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
Informative References
RFC2429 Bormann, C., Cline, L., Deisher, G., Gardos, T., Maciocco,
C., Newell, D., Ott, J., Sullivan, G., Wenger, S. and C.
Zhu, "RTP Payload Format for the 1998 Version of ITU-T Rec.
H.263 Video (H.263+)", RFC 2429, October 1998.
RFC3267 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.
Authors' Contact Information
Roberto Castagno Nokia Mobile Phones PO Box 88, FIN-33721 Tampere (Tieteenkatu 1, FIN-33720 Tampere) Finland
Phone: +358 7180 35796 EMail: [email protected]
David Singer Apple Computer, Inc. One Infinite Loop, MS:302-3MT Cupertino CA 95014 USA
Phone: +1 408 974 3162 EMail: [email protected]
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