RFC 4723

RFC 4723: Registration of Media Type audio/mobile-xmf 🎀

okay bestie, this is RFC 4723 and it's giving "official paperwork but make it cute" 💖 Written by Timo Kosonen (Nokia) and Tom White (MIDI Manufacturers Association, MMA) in December 2006. It's Informational 🧚, so it's sharing info with the Internet community and is NOT a standard. It doesn't obsolete or update any other RFC (none are listed in the title block) ✨

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Status of This Memo ✨

this memo is just providing info for the Internet community. it doesn't specify an Internet standard of any kind 🫶 distribution is unlimited, so share it wherever 💅

Copyright Notice 🔥

Copyright (C) The IETF Trust (2006).

Abstract 🌸

so the MIDI Manufacturers Association (MMA) and the Association of Musical Electronics Industry (AMEI) made the Mobile XMF standard, and it was built specifically for mobile MIDI apps 🎶 Mobile XMF is super compact and gives you high-quality synthetic audio for music downloads and messaging apps that need MIME registration. this doc registers the media type audio/mobile-xmf and honestly it's a whole vibe 🦋

1. Introduction 💖

MIDI content is everywhere on the Internet ngl 🌈 usually MIDI data lives in the Standard MIDI File (SMF) format [8]. this MIME type registration uses the Mobile XMF file format to wrap up SP-MIDI [3,4] and Mobile DLS (Downloadable Sounds) [2] data. it's giving packaging 🎀

MMA and AMEI made the Mobile XMF standard [1], built for mobile MIDI [7] apps. iconic behavior from the MIDI crew ✨

2. Registration of audio/mobile-xmf 👑

Type name: audio 💅

Subtype name: mobile-xmf 💅

Required parameters: none 🌸

Optional parameters:

revision 🦋

revision is the Mobile XMF file type revision ID number from the XmfFileTypeRevisionID field of the XMF Meta File format 2.00. it's encoded in hex in US-ASCII. main character energy 💜

prl: Playback resource list 🧚

okay so prl holds the playback resources that show up in all Content Description MetaDataItems of the Mobile XMF file. it's made of two-digit hexadecimal numbers that represent data bytes from the Content Description Meta Data 🍓 each resource is listed exactly once (no doubles, bestie 🙈). a playback resource has two parts: a prefix and data. prl is a sequence of two-digit hex numbers encoded in US-ASCII, so it always has an even number of hex digits ✨

Example: if the file includes Playback Resource Lists such as [00h 01h 00h 02h] and [00h 01h 00h 03h], the matching prl is 000100020003, containing playback resources 01, 02, and 03, each with the prefix 00. 🎀

minimum-pr: Minimum playback requirements 🔥

ngl this one is the big one 😭 minimum-pr holds the Maximum Instantaneous Resource (MIR) values from the first row of all MIR Count Tables for the playback resources listed in prl. only the largest value from the values of the same resource gets picked. minimum-prl is a sequence of two-digit hex numbers encoded in US-ASCII, so it has an even number of hex digits too 💖

minimum-pr requires the use of prl, and the values in minimum-pr must be in the same order as the resources in prl. minimum-pr is the more important of minimum-pr and total-pr, because it defines the minimum playback requirements. it's the MVP 👑

Example: if the file includes the first rows of MIR Count Tables such as [02h 00h] and [01h 01h] matching the Playback Resource Lists above, the minimum-pr is 020001. (02 is the largest of 2 and 1, 00 is the largest of 0, and 01 is the largest of 1.) 🧠

total-pr: Total playback requirements 🌈

total-pr holds the MIR values from the last row of all MIR Count Tables for the playback resources listed in prl. only the largest value from the values of the same resource is chosen. total-pr is a sequence of two-digit hex numbers encoded in US-ASCII, so it has an even number of hex digits 🫶

total-pr requires the use of prl, and the values in total-pr must be in the same order as the resources in prl.

Example: if the file includes the last rows of MIR Count Tables such as [05h 02h] and [06h 01h] matching the Playback Resource Lists above, the total-pr is 060201. (06 is the largest of 5 and 6, 02 is the largest of 2, and 01 is the largest of 1.) 💅

Encoding considerations: 🌸

mobile-xmf data is binary data and must be encoded for non-binary transport. Base64 [9] is suitable for Email 📧

Security considerations: 🔐

okay this section is serious, bestie 😭 lots of synthetic audio compositions come with intellectual property rights 💜 it's totally conceivable that rights owners of mobile-xmf content will want to protect their stuff with security mechanisms that block rendering unless you've got a legally acquired license. those mechanisms get applied externally to the Content-Type defined here, so mobile-xmf content itself is NOT encrypted internally. mobile-xmf streams don't contain executable content, which is a relief 🙌 Mobile XMF players are robust against corrupted mobile-xmf content, because they ignore unidentified content 🛡️ and the prl, minimum-pr, and total-pr parameters can be used to represent Mobile DLS playback memory requirements, which protects against excessive playback memory usage 🧚

Interoperability considerations: 🦋

Mobile XMF is a Musical Instrument Digital Interface (MIDI) specification developed by MMA and AMEI. it's based on the XMF Meta File Format Specification v2.00 [5,6], which standardizes a meta file format for electronic distribution of music. mobile-xmf data is stored in XMF file format [5,6] 🎶

Published specification: 📜

Mobile XMF Content Format Specification, MMA specification v1.0., RP-42, Los Angeles, CA, USA. 2004.

Specification is available from: http://www.midi.org/about-midi/specshome.shtml

Applications which use this media type: 📱

mobile-xmf is a synthetic audio format for the flexible presentation of SP-MIDI and Mobile DLS instrument data on a wide range of playback devices, especially portable stuff like mobile phones, PDAs, and palmtop computers 💖

Additional information: ✨

Magic number(s), first twelve bytes:

\130\115\106\137\062\056\060\060\000\000\000\002

File extension(s): mxmf 🍓

Macintosh File Type Code(s): mxmf 🍓

Person & email address to contact for further information: Timo Kosonen, timo.kosonen@nokia.com 💌

Intended usage: COMMON 🌈

Restrictions on usage: none 🫶

Authors: Timo Kosonen (timo.Kosonen@nokia.com) and Tom White (twhite@midi.org) 👯

Change controller: MIDI Manufacturers Association, P.O. Box 3173, La Habra, CA 90632-3173, Tel (714) 736-9774, Fax (714) 736-9775. Point of contact: Tom White, twhite@midi.org 📞

3. Security Considerations 🔐

Security considerations are specified in the MIME subtype registration contained in Section 2. so go read that 👀

4. IANA Considerations 🧚

Section 2 of this document registers one MIME subtype. one subtype, zero drama ✨

5. Normative References 📚

• [1] Mobile XMF Content Format Specification, MMA specification v1.0., RP-42, Los Angeles, CA, USA. 2004.
• [2] Mobile DLS, MMA specification v1.0., RP-41, Los Angeles, CA, USA. 2004.
• [3] Scalable Polyphony MIDI Specification. December 2001, RP-034, The MIDI Manufacturers Association, Los Angeles, CA, USA.
• [4] Scalable Polyphony MIDI Device 5-24 Note Profile for 3GPP, December 2001, RP-035, The MIDI Manufacturers Association, Los Angeles, CA, USA.
• [5] Specification for XMF Meta File Format, Version 1.00b. The MIDI Manufacturers Association, Los Angeles, CA, USA, 2001.
• [6] XMF Meta File Format 2.00, RP-043, MIDI Manufacturers Association, Los Angeles, CA, USA, 2004
• [7] MIDI 1.0 Detailed Specification, Document Version 4.2. February 1996, In 'The Complete MIDI 1.0 Detailed Specification, Document Version 96.1.' The MIDI Manufacturers Association., Los Angeles, CA, USA.
• [8] Standard MIDI Files 1.0, In 'The Complete MIDI 1.0 Detailed Specification, Document Version 96.1.' The MIDI Manufacturers Association., Los Angeles, CA, USA.
• [9] Josefsson, S., "The Base16, Base32, and Base64 Data Encodings", RFC 4648, October 2006.

Authors' Addresses 💌

Timo Kosonen
Nokia
P.O. Box 100
33721 Tampere
Finland

Tel: +358 5048 35206
Fax: +358 7180 35899
EMail: timo.kosonen@nokia.com

Tom White
MIDI Manufacturers Association
P.O. Box 3173
La Habra, CA  90632-3173
USA

Tel: (714) 736-9774
Fax: (714) 736-9775
EMail: twhite@midi.org

Full Copyright Statement 📜

Copyright (C) The IETF Trust (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, THE IETF TRUST, 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 currently provided by the Internet Society. ✨