RFC 4393

MIME Type Registrations for 3GPP2 Multimedia Files

📅 published March 2006, from ietf

RFC 4393: MIME Type Registrations for 3GPP2 Multimedia Files 🎀

Author: H. Garudadri (Harinath Garudadri), QUALCOMM Working group: Network Working Group Category: Standards Track Date: March 2006 Obsoletes / Updates: none listed in the header, so this one doesn't replace or update any earlier RFC 🦋

Status of This Memo ✨

Okay so this doc is a standards track protocol for the Internet community 🌸 and it's basically asking everyone to talk about it and send in suggestions for making it better. For the standardization state and status of this protocol, check the current edition of "Internet Official Protocol Standards" (STD 1). And distribution of this memo is unlimited, so share away 💅

Copyright Notice 🌈

Abstract 🧚

This doc is all about registering and documenting the standard MIME types for the 3GPP2 multimedia file format 📁. That format is part of the family based on the ISO Media File Format, so it's giving family reunion vibes 🫶

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 ✨

So the third-generation partnership project 2 (3GPP2) for 3rd generation cellular telephony has defined a standard file format for audio/visual sequences that can get downloaded onto cellular phones [3gpp2] 📱. At the time of writing, a 3G2 file (the 3GPP2 file format) can contain H.263, H.264, or MPEG-4 video 🎥. It can also hold 13K Vocoder, EVRC or AMR Narrow-band speech, or AAC audio 🎧, plus 3GPP timed text 💬.

Inside the file, just like every file in the 'ISO' family, there's an intrinsic file-type box 📦. It tells you which specifications the file complies with, and which players (possibly compliant with only one specification) the content author lets play it. This is all identified through four-letter 'brands' 🔖. Any file tagged with the MIME [MIME1] type defined in this document MUST contain, in its 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 so these files get identified correctly when they're served over HTTP, included in multi-part documents, or used anywhere else MIME types show up 🦋.

1.1. Conventions Used in This Document 🎀

Here's the deal with the key words in this doc 💅. 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 🚨

Real talk, this section is serious 😭. The 3GPP2 file format can contain audio, video, and displayable text data. There is currently no provision for 'active' elements (such as scripts) of any kind, so no sneaky scripts riding along in your cute little video file 🙅‍♀️.

Clearly, it's possible to author malicious files that try to call for an excessively large picture size, high sampling-rate audio, and so on 💀. However, clients can, and usually do, protect themselves against this kind of attack 🛡️.

It should be noted that selected metadata fields may hold information partly meant to protect the media against unauthorized use or distribution 🔐. In this case, the intention is that altering or removing the data in that 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's 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, which would bring extra security risks 🚩. But this type of capability is currently not supported in the referenced specification, so we're safe for now ✨.

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). Think of it as the audio-only lane 🎶.

Here's the registration template, copied exactly so nothing gets lost in translation 💖:

   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

Full Copyright Statement ✨

Okay, the legal bit, but make it cute. 💅 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 🎀

So, the IETF is not picking a side on whether any Intellectual Property Rights (or other rights) might cover the tech in this document, or whether you'd be able to get a license for them. It also isn't saying it went looking for any of that. 🧚 For how RFC rights work, check out BCP 78 and BCP 79.

Any IPR disclosures sent to the IETF Secretariat, plus assurances of licenses, and the results of anyone trying to get a general license or permission to use those proprietary rights for implementing or using this spec, can be found in the IETF's online IPR repository at http://www.ietf.org/ipr. 📚

The IETF also invites anyone to flag any copyrights, patents, patent applications, or other proprietary rights that might cover technology needed to implement this standard. Send those to the IETF at ietf-ipr@ietf.org. 💜

Acknowledgement 🫶

Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). 🌈

📦 where this page comes from

ietf: rfc4393 2006-03
💖 girlified by claude-haiku-5-5 on 2026-10-16: a language model's rewrite of the original, under its terms