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Network Working Group
Request for Comments: 4393
Category: Standards Track
H. Garudadri
QUALCOMM
March 2006

MIME Type Registrations for 3GPP2 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 © The Internet Society (2006).

Abstract

This document serves to register and document the standard MIME types associated with the 3GPP2 multimedia file format, which is part of the family based on the ISO Media File Format.

Table of Contents

   1. Introduction ....................................................1
      1.1. Conventions Used in This Document ..........................2
   2. Security Considerations .........................................2
   3. MIME Types ......................................................3
      3.1. Files with Audio but No Video ..............................3
      3.2. Any Files ..................................................4
   4. IANA Considerations .............................................5
   5. Acknowledgements ................................................6
   6. References ......................................................6
      6.1. Normative References .......................................6
      6.2. Informative References .....................................6

1. Introduction

The third-generation partnership project 2 (3GPP2) for 3rd generation cellular telephony has defined a standard file format to contain audio/visual sequences that may be downloaded to cellular phones [3gpp2]. At the time of writing, the 3GPP2 file format (3G2) can contain H.263, H.264, or MPEG-4 video; and 13K Vocoder, EVRC or AMR Narrow-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 in this document MUST contain, in their compatible brands list, a brand defined in a standard (issued by 3GPP2) that can apply to 3GPP2 files.

The MIME types defined in this document are needed correctly to identify such files when they are served over HTTP, included in multi-part documents, or used in other places where MIME types are used.

1.1. Conventions Used in This Document

In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in RFC 2119 [RFC2119].

2. Security Considerations

The 3GPP2 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 that 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 agreement-based World Intellectual Property Organization (WIPO) treaties.

3GPP2 files have an extensible structure, so it is theoretically possible that metadata fields or media formats could be defined in the future that could be used to induce particular actions on the part of the recipient, thus presenting additional security risks; but this type of capability is currently not supported in the referenced specification.

Encryption, signing, or authentication of these file formats can be done using any media-independent transformations of the file or media data.

3. MIME Types

This registration applies to all files defined as using the '3G2' file format and identified with a suitable brand in a 3GPP2 specification. The usual file suffix for all these files is ".3g2".

3.1. Files with Audio but No Video

The type "audio/3gpp2" may be used for files containing audio but no visual presentation (neither video nor timed text, for example). 

   To: ietf-types@iana.org
   Subject:  Registration of Standard MIME media type audio/3gpp2
   
   MIME media type name:
       audio
   MIME subtype name:
       3gpp2
   Required parameters:
       None.
   Optional parameters:
       Codecs. See [Bucket].  If the audio/3gpp2 body part contains
       another container format, the Codecs parameter MUST list all
       codecs indicated by all formats, including any contained formats.
   Optional parameter values:
       [3gpp2]
   Encoding considerations:
       This data is 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 13K vocoder speech [RFC2658].
   Security considerations:
       See the security considerations section in RFC 4393 (this
       document).
   Interoperability considerations:
       The 3GPP2 organization has defined the specification of the media
       format [3gpp2].  Interoperability and conformance testing is done
       in cooperation with other bodies, including the Open Mobile
       Alliance (OMA) <http://www.openmobilealliance.org> and the
       International Multimedia Telecommunications Consortium (IMTC)
       <http://www.imtc.org/>.
   Published specification:
       3GPP2 C.S0045, 3GPP2 C.S0050 [3gpp2]
       3GPP2 specifications are publicly accessible at the 3GPP2 web
       site, <http://www.3gpp2.org>.
   Applications that use this media type:
       Multi-media
   Additional information:
       The type "audio/3gpp2" 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 visual material).
   Magic number(s):
       None.  However, the file-type box must occur first in the file,
       and MUST contain a 3GPP2 brand in its compatible brands list.
   File extension(s):
       3g2 and 3gpp2 are both declared at <http://www.nist.gov/nics/>;
       3g2 is preferred.
   Macintosh file type code(s):
       '3gp2'
   Person & email address to contact for further information:
       H. Garudadri, hgarudadri@qualcomm.com
   Intended usage:
       COMMON
   Change controller:
       3GPP2

3.2. Any Files

The type "video/3gpp2" is valid for all files. It is valid to serve an audio-only file as "video/3gpp2". 

   To: ietf-types@iana.org
   Subject:  Registration of Standard MIME media type video/3gpp2
   
   MIME media type name:
       video
   MIME subtype name:
       3gpp2
   Required parameters:
       None
   Optional parameters:
       Codecs. See [Bucket].  If the video/3gpp2 body part contains
       another container format, the Codecs parameter MUST list all
       codecs indicated by all formats, including any contained formats.
   Optional parameter values:
       [3gpp2]
   Encoding considerations:
       This data is 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 13K
       vocoder speech [RFC2658].
   Security considerations:
       See the security considerations section in RFC 4393 (this
       document).
   Interoperability considerations:
       The 3GPP2 organization has defined the specification of the media
       format [3gpp2].  Interoperability and conformance testing is done
       in cooperation with other bodies, including the Open Mobile
       Alliance (OMA) <http://www.openmobilealliance.org> and the
       International Multimedia Telecommunications Consortium (IMTC)
       <http://www.imtc.org/>.
   Published specification:
       3GPP2 C.S0045, 3GPP2 C.S0050 [3gpp2]
   
       3GPP2 specifications are publicly accessible at the 3GPP2 web
       site, <http://www.3gpp2.org>.
   Applications that 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 3GPP2 brand in its compatible brands list.
   File extension(s):
       3g2 and 3gpp2 are both declared at <http://www.nist.gov/nics/>;
       3g2 is preferred.
   Macintosh file type code(s):
       '3gp2'
   Person & email address to contact for further information:
       H.Garudadri, hgarudadri@qualcomm.com
   Intended usage:
       COMMON
   Change controller:
       3GPP2

4. IANA Considerations

This document registers the MIME media types audio/3gpp2 and video/3gpp2, defined above.

5. Acknowledgements

This document used RFC 3839 as a template. The authors of RFC 3839, R. Castagno, and D. Singer, are gratefully acknowledged.

6. References

6.1. Normative References

   [3gpp2]   Published specifications:  C.S0050: 3GPP2 File Formats for
             Multimedia Services.  C.S0045:  Multimedia Messaging
             Service (MMS) Media Format and Codecs for cdma2000 Spread
             Spectrum Systems.
   
   [Bucket]  Gellens, R., Singer, D., and P. Frojdh, "The Codecs
             Parameter for "Bucket" Media Types", RFC 4281, November
             2005.
   
   [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.

6.2. 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.
   
   [RFC2658] McKay, K., "RTP Payload Format for PureVoice(tm) Audio",
             RFC 2658, August 1999.

Author's Address

Harinath Garudadri
Qualcomm Inc
5775 Morehouse Dr.
San Diego, CA 92121 

   Phone: +1 858 651 6383
   EMail: hgarudadri@qualcomm.com

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Copyright © The Internet Society (2006).

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