Network Working Group|
Request for Comments: 3839
Category: Standards Track
Nokia Mobile Phones
Apple Computer, Inc.
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 © The Internet Society (2004).
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.
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.
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.
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".
The type "audio/3gpp" may be used for files containing audio but no visual presentation (neither video nor timed text, for example).
Subject: Registration of Standard MIME media type audio/3gpp
The type "video/3gpp" is valid for all files. It is valid to serve an audio-only file as "video/3gpp".
Subject: Registration of Standard MIME media type video/3gpp
This document registers the MIME types audio/3gpp and video/3gpp, defined above.
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.
[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.
[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.
Nokia Mobile Phones
PO Box 88, FIN-33721 Tampere
(Tieteenkatu 1, FIN-33720 Tampere)
Phone: +358 7180 35796
Apple Computer, Inc.
One Infinite Loop, MS:302-3MT
Cupertino CA 95014
Phone: +1 408 974 3162
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