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Versions: 00 01 02 03 rfc3003                            Standards Track
Internet Engineering Task Force                               M. Nilsson
INTERNET DRAFT                                            27 August 2000
Document: draft-nilsson-audio-mpeg-03.txt
Expires 27 February 2001


                      The audio/mpeg Media Type

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as ``work in progress.''

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.


Abstract

   The audio layers of the MPEG-1 and MPEG-2 standards are in frequent
   use on the internet, but there is no uniform MIME type for these
   files. The intention of this draft is to define the media type
   audio/mpeg to refer to this kind of contents.

   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 RFC 2119 [RFC2119].

1.  MPEG audio

   The audio compression defined as layer I, layer II and layer III in
   the MPEG-1 [MPEG-1] and MPEG-2 [MPEG-2] standards is a popular method
   of compressing audio with a low quality loss. The compressed audio is
   split into several small data frames, each containing a frame header
   and compressed audio data.

   The mime type audio/mpeg defines a elementary byte stream containing
   MPEG frames according to [MPEG-1] and [MPEG-2], possibly interspersed
   with non MPEG data. Non MPEG data is data without MPEG
   synchronisation or in other ways not possible to decompress without
   error.




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Internet DRAFT        The audio/mpeg Media Type              August 2000

   Typically MPEG audio meta data is concatenated with the MPEG stream,
   e.g. the meta data format ID3 puts a 128 byte data block in the end
   of the stream while ID3v2 [ID3V2] prepends a data block of variable
   size to the stream.

   NOTE: MPEG audio was not designed as a file format but as a format
   for transmitting audio streams. As such, it does not have any
   well defined way of including meta data along with audio information.
   Some products embed meta data using zero amplitude frames or
   disguised as transmission errors. Others embed the MPEG data in WAV
   format.


2.  Registration Information

   To: ietf-types@iana.org
   Subject: Registration of MIME media type audio/mpeg

   MIME media type name: audio

   MIME subtype name: mpeg

   Required parameters: none

   Optional parameters: none

   Encoding considerations:

       For use over internet it is assumed that lower layers take care
       of transmission errors, so audio/mpeg data MAY include MPEG
       frames generated without the optional cyclic redundancy checks
       (CRC) for improved audio quality.

       The MPEG audio data is binary data, and must be encoded for
       non-binary transport; the Base64 encoding is suitable for Email.
       Note that the MPEG audio data does not compress easily using
       lossless compression.

   Security considerations:

        MPEG is a tagged data format, and some tags are available for
        private use. As such, arbitrary material could potentially
        be transferred in the MPEG stream, including executable content.
        Tagged data containing executable content SHOULD never be sent
        and MUST not be executed if it is received.

                                NOTE

            The requirement that such content not be executed on receipt
            is especially important since situations exist where content
            will be generated independently and therefore could contain
            executable content that the sender is unaware of.

        Audio/mpeg objects are not signed or encrypted internally.
        External security mechanisms must be employed to ensure content
        confidentiality


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Internet DRAFT        The audio/mpeg Media Type              August 2000

   Interoperability considerations:

       MPEG audio has proven to be widely interoperable across computer
       platforms.

   Published specification: see [MPEG-1] and [MPEG-2]

   Applications which use this media type:

       MPEG audio is device-, platform- and vendor-neutral and is
       supported by a wide range of encoders and decoders (players).

   Additional information:

       Magic number(s): none
       File extension(s): .mp1, .mp2, .mp3
       Macintosh File Type Code(s): MPEG
       Object Identifier(s) or OID(s): none

   Person & email address to contact for further information:

       The author of this draft.

   Intended usage: COMMON

   Author/Change controller: Martin Nilsson (see section 5)


3.  References

   [ID3v2]
     Martin Nilsson, "ID3 tag version 2.3.0".
     <url:http://www.id3.org/id3v2.3.0.txt>

   [MPEG-1]
     ISO/IEC 11172-3:1993.
     Coding of moving pictures and associated audio for digital storage
     media at up to about 1,5 Mbit/s, Part 3: Audio.
     Technical committee / subcommittee: JTC 1 / SC 29

   [MPEG-2]
     ISO/IEC 13818-3:1995
     Generic coding of moving pictures and associated audio information,
     Part 3: Audio.
     Technical committee / subcommittee: JTC 1 / SC 29

     and

     ISO/IEC DIS 13818-3
     Generic coding of moving pictures and associated audio information,
     Part 3: Audio (Revision of ISO/IEC 13818-3:1995)




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Internet DRAFT        The audio/mpeg Media Type              August 2000

   [RFC2119]
     S. Bradner, "Key words for use in RFCs to Indicate Requirement
     Levels", RFC 2119, March 1997.

        <url:ftp://ftp.isi.edu/in-notes/rfc2119.txt>


4.  Full Copyright Statement

   Copyright (C) The Internet Society (2000).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implmentation may be prepared, copied, published and
   distributed, in whole or in part, without restriction of any kind,
   provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS 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."


5.  Authors Address

   Martin Nilsson
   Rydsv„gen 246 C. 30
   S-584 34 Link÷ping
   Sweden

   Email: nilsson@id3.org











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