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Network Working Group P. Frojdh
Request for Comments: 4613 U. Lindgren
Category: Informational M. Westerlund
Ericsson
September 2006
Media Type Registrations for Downloadable Sounds
for Musical Instrument Digital Interface (MIDI)
Status of This Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This document serves to register a media type for Downloadable
Sounds.
Table of Contents
1. Introduction ....................................................1
2. Security Considerations .........................................2
3. IANA Considerations .............................................2
3.1. Media Type for Downloadable Sounds .........................3
4. References ......................................................5
4.1. Normative References .......................................5
4.2. Informative References .....................................5
1. Introduction
The present document seeks to register a media type for Downloadable
Sounds (DLSes). The DLS format is used to define instruments for
widely used wavetable synthesizers associated with the standards
[DLS1, DLS2, MDLS]. DLSes and their associated standards are
maintained and defined by two organizations, the Musical Instrument
Digital Interface (MIDI) Manufacturers Association (MMA) and the
Association of the Musical Electronics Industry (AMEI).
The media type defined here is needed to identify DLS files correctly
when they are served over HTTP, included in multi-part documents, or
used in other places where media types are used.
Frojdh, et al. Informational [Page 1]
RFC 4613 Media Type Registrations for MIDI September 2006 2. Security Considerations The DLS format may contain audio, displayable text data, and modeling parameters (a.k.a. articulation parameters). In addition, the DLS format contains a so-called conditional chunk that is 'active' in the sense that it affects the execution of a DLS file parser. However, the DLS format does not currently define any scripting mechanism. Clearly, it is possible to author malicious files that, for example, contain large amounts of data always blocked by a conditional statement; i.e., no synthesizer loads the instruments. However, for DLS, clients can and usually do protect themselves against these kinds of attacks. A key point is that conditional chunks are optional, that is, a parser does not have to execute a conditional chunk. However, if a parser evaluates a conditional chunk, it is still possible to parse its content and draw to a conclusion as to whether it is usable for a particular synthesizer engine. Note that selected metadata fields may include 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 agreements based on World Intellectual Property Organization (WIPO) treaties. DLS have an extensible structure, making it theoretically possible to define metadata fields or media formats in the future that could be used to induce particular actions of the recipient, and thus that would present additional security risks. However, this type of capability is currently not supported in the referenced specifications. There is no current provision in the DLS standard for encryption, signing, or authentication within the file formats. 3. IANA Considerations The IANA has registered the media type audio/dls, as specified in Section 3.1. The registration uses the template present in [RFC4288]. Frojdh, et al. Informational [Page 2]
RFC 4613 Media Type Registrations for MIDI September 2006 3.1. Media Type for Downloadable Sounds Type name: audio Subtype name: dls Required parameters: None Optional parameters: 'dls-type' A comma-separated list of the dls types (one or more) that the file content conforms to. The following values are specified: 0, 1, and 2 signify Downloadable Sounds Level 1.1b content, Downloadable Sounds Level 2.1 content, and Mobile Downloadable Sound content, respectively. All types that the content conforms to should be indicated. Further values (integers) may be specified in the future, and any unknown values shall be ignored. If the parameter is not specified, it corresponds to a value equal to 0; i.e., the content conforms to Downloadable Sound level 1.1b. Encoding considerations: DLS files are binary and should be transmitted in a suitable encoding without CR/LF conversion, 7-bit stripping etc.; base64 [RFC3548] is a suitable encoding. Security considerations: see the security considerations in Section 2 of RFC 4613. Interoperability considerations: This media type is for consumption by a MIDI player capable of utilizing downloadable sounds for its synthesizers. A general-purpose audio player will not be capable of utilizing the audio within the format without explicit support of the format. Frojdh, et al. Informational [Page 3]
RFC 4613 Media Type Registrations for MIDI September 2006 Published specification: Downloadable Sounds Level 1.1b [DLS1], Downloadable Sounds Level 2.1 [DLS2], and Mobile Downloadable Sounds [MDLS]. MMA specifications can be ordered from the MMA web site, www.midi.org. Applications that use this media type: Multi-media Additional information: Magic number(s): The ninth to twelfth bytes of the file must equal (in hexadecimal notation) 44, 4c, 53, and 20, respectively. File extension(s): .dls is declared at http://www.nist.gov/nics Person & email address to contact for further information: Ulf A. Lindgren, ulf.a.lindgren@ericsson.com Intended usage: COMMON Restrictions on usage: None Author: Per Frojdh Ulf A. Lindgren Magnus Westerlund Change controller: MIDI Manufacturers Association http://www.midi.org info@midi.org Frojdh, et al. Informational [Page 4]
RFC 4613 Media Type Registrations for MIDI September 2006 4. References 4.1. Normative References [DLS1] "Downloadable Sounds Level 1.1b", MMA/AMEI specification v1.1b, Los Angeles, CA, USA, 2004. [DLS2] "Downloadable Sounds Level 2.1", MMA/AMEI specification v1.0, Los Angeles, CA, USA, 2001. [MDLS] "Mobile Downloadable Sounds 1.0", MMA specification v1.0, Los Angeles, CA, USA, 2004. [RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and Registration Procedures", BCP 13, RFC 4288, December 2005. 4.2. Informative References [RFC3548] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 3548, July 2003. Authors' Addresses Per Frojdh Ericsson AB Ericsson Research SE-164 80 Stockholm Sweden EMail: per.frojdh@ericsson.com Ulf A. Lindgren Ericsson AB Ericsson Research SE-417 56 Goteborg Sweden EMail: ulf.a.lindgren@ericsson.com Magnus Westerlund Ericsson AB Ericsson Research SE-164 80 Stockholm Sweden EMail: magnus.westerlund@ericsson.com Frojdh, et al. Informational [Page 5]
RFC 4613 Media Type Registrations for MIDI September 2006 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). Frojdh, et al. Informational [Page 6]