Movatterモバイル変換

Network Working Group                                         M. NilssonRequest for Comments: 3003                                 November 2000Category: Standards TrackThe audio/mpeg Media TypeStatus 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 (2000).  All Rights Reserved.Abstract   The audio layers of the MPEG-1 and MPEG-2 standards are in frequent   use on the internet, but there is no uniform Multipurpose Internet   Mail Extension (MIME) type for these files.  The intention of this   document 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 inRFC 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   synchronization or in other ways not possible to decompress without   error.   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 variableNilsson                     Standards Track                     [Page 1]

RFC 3003               The audio/mpeg Media Type           November 2000   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.   NOTE: The audio/MPS mime type is in use in addition to the   audio/mpeg.  The MPA [RFC 1890] sub-type refers to MPEG audio when it   is segmented and send as a Realtime Transport Protocol (RTP) payload.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.Nilsson                     Standards Track                     [Page 2]

RFC 3003               The audio/mpeg Media Type           November 2000                                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   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 document.   Intended usage: COMMON   Author/Change controller: Martin Nilsson (seesection 5)   3.  Security Considerations   Security considerations are discussed in the security considerations   clause of the MIME registration insection 2.Nilsson                     Standards Track                     [Page 3]

RFC 3003               The audio/mpeg Media Type           November 20004.  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)   [RFC2119]     Bradner, S., "Key words for use in RFCs to Indicate Requirement     Levels",BCP 14,RFC 2119, March 1997.5.  Author's Address   Martin Nilsson   Rydsvagen 246 C. 30   S-584 34 Linkoping   Sweden   EMail: nilsson@id3.orgNilsson                     Standards Track                     [Page 4]

RFC 3003               The audio/mpeg Media Type           November 20006.  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 implementation 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.Acknowledgement   Funding for the RFC Editor function is currently provided by the   Internet Society.Nilsson                     Standards Track                     [Page 5]