RFC 4393 PROPOSED STANDARD MIME · MEDIA TYPES · MULTIMEDIA

3GPP2 MIME Types: MIME Type Registrations for 3GPP2 Multimedia Files

Registers audio/3gpp2 and video/3gpp2 so 3G2 phone media files can be labeled correctly over HTTP and in multipart documents.

On rfc-editor.org ↗
PUBLISHED
March 2006
AUTHORS
H. Garudadri
STREAM
IETF
UPDATED BY
RFC 6381 — The 'Codecs' and 'Profiles' Parameters for "Bucket" Media Types
TYPES REGISTERED
audio/3gpp2, video/3gpp2
PREFERRED FILE EXTENSION
3g2
MACINTOSH FILE TYPE CODE
'3gp2'
CHANGE CONTROLLER
3GPP2
DOI
10.17487/RFC4393

RFC text

Contents
Original text · RFC Editor View on rfc-editor.org ↗
Network Working Group                                       H. Garudadri
Request for Comments: 4393                                      QUALCOMM
Category: Standards Track                                     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 (C) 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

Full Copyright Statement

   Copyright (C) The Internet Society (2006).

   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 provided by the IETF
   Administrative Support Activity (IASA).

AI ELI5

On this page
PROBLEMThe 3GPP2 file format for audio and video on cellular phones had no registered MIME types, so servers could not label such files correctly.
MECHANISMThe RFC registers two types, audio/3gpp2 for files with audio but no visual material and video/3gpp2 for any file, with the usual suffix .3g2.
STATUS TODAYIt is a Proposed Standard that has since been updated by RFC 6381.

§1Introduction

The third-generation partnership project 2 (3GPP2) defined a standard file format, called 3G2, for audio and visual sequences that can be downloaded to cellular phones. At the time of writing, it can hold H.263, H.264 or MPEG-4 video; 13K Vocoder, EVRC or AMR Narrow-band speech, or AAC audio; and 3GPP timed text.

Like all files in the ISO family, a 3G2 file has a file-type box that lists four-letter brands. Files labeled with the types in this RFC MUST list, in their compatible brands, a brand defined in a 3GPP2 standard. The MIME types are needed to identify such files when served over HTTP, included in multi-part documents or used elsewhere MIME types appear.

A phone video file has a tag inside saying what it is. The new labels outside the file let computers know what it is without opening it.

§3The Two Registered Types

The registration covers all files in the 3G2 format identified with a suitable brand in a 3GPP2 specification. The usual suffix is .3g2; the registrations also declare 3gpp2, with 3g2 preferred. The Macintosh file type code is '3gp2'.

audio/3gpp2 may be used for files containing audio but no visual presentation. Such files MUST NOT contain any visual material, and the RFC notes that 3GPP timed text counts as visual. video/3gpp2 is valid for all files, and it is valid to serve an audio-only file as video/3gpp2.

Both types have no required parameters and one optional parameter, Codecs, defined in RFC 4281. If the body contains another container format, Codecs MUST list all codecs of all formats, including contained ones. Both list the 3GPP2 specifications C.S0045 and C.S0050 as published specifications, and 3GPP2 is the change controller.

There are two labels. One says 'sound only', and the other says 'might have pictures'. The picture label also works for sound-only files.

§4Encoding and Identification

The data is binary. It should be transmitted in a suitable encoding without CR/LF conversion or 7-bit stripping; base64 is a suitable encoding. These types are for files only. Real-time transfer uses separate types, such as the RTP payload formats for 13K vocoder speech (RFC 2658) and, for video, H.263 (RFC 2429).

There is no magic number as such. However, the file-type box must occur first in the file and MUST contain a 3GPP2 brand in its compatible brands list.

These files are not plain text, so they must be sent without anyone fiddling with the bytes. The first thing inside the file says what kind it is.

§2Security Considerations

The format can hold audio, video and displayable text, and has no provision for active elements such as scripts. Files could still be crafted to demand an excessively large picture size or high sampling-rate audio, though clients can and usually do protect themselves.

Some metadata fields may carry information meant to protect media against unauthorized use, and altering or removing it is intended to be treated as an offense under WIPO treaties. The format is extensible, so future fields could in theory induce actions in the recipient, but the referenced specification does not support that. Encryption, signing or authentication can be done with any media-independent transformation.

The files only hold sound, pictures and text, not programs. A bad file might be oversized to cause trouble, but players are usually careful.

§3.1Interoperability and Conformance

Both registrations say that 3GPP2 defined the specification of the media format. Interoperability and conformance testing is done in cooperation with other bodies, including the Open Mobile Alliance (OMA) and the International Multimedia Telecommunications Consortium (IMTC). The intended usage is COMMON and the application area is listed as multi-media.

Several groups work together to check that phones and players all understand these files the same way.

§4IANA Considerations

The only IANA action is to register the two MIME media types audio/3gpp2 and video/3gpp2, as defined in the document. The RFC used RFC 3839 as a template for the registrations.

The official list of labels gets two new entries, and that is all this RFC asks for.

§7References