Sustainability of Digital Formats
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Identification and description

Full name	eXtensible Music Format (XMF)
Description	Wrapper format for MIDI, Downloadable Sounds (DLS), and WAVE waveform data. From the specification from MIDI.org: "XMF is low-overhead meta-file format . . . . primarily intended to bundle existing standard music and sound file formats--such as SMF, DLS, and WAV--and not to replace any of them." (RP-030, p.2) MIDI and audio data may be encapsulated in the XMF file or be linked via external URI reference. The second part of the specification (RP-031) discusses Type 0 and Type 1 files: "both must contain at least one SMF file; inclusion of DLS files is optional" (p. 1), and "the SMF file images in an XMF Type 0 file are guaranteed to be streamable." (RP-031, p. 2) [Is there a type that only contains external references to SMF and/or DLS data?]
Production phase	May be used by composers or arrangers for initial-state activities, in middle-state exchange of data or archiving, or for final-state, end-user delivery.
Relationship to other formats
May contain	SMF, Standard MIDI File Format
May contain	DLS, Downloadable Sounds Format

Local use

LC experience or existing holdings	None
LC preference	None established at this time

Sustainability factors

Disclosure	Fully documented. Developed by the MIDI Manufacturers Association.
Documentation	XMF Specification (2001), available for purchase from MIDI.org; contains three parts: RP-030, general specification; RP-031, Type 1 and Type 0 files; and RP-032, meta event and patch type prefix.
Adoption	Not known to the compilers of this document.
Licensing and patent claims	None identified by the compilers of this document.
Transparency	Transparent wrapper. See also MIDI_SD and DLS.
Self-documentation	Provided by MetaDataItems, which may be placed at any node in the file and may include technical, copyright, or descriptive information, e.g., title, name, author, etc. The specification speaks of a future plan to specify an XML semantic equivalent to the current mechanism.
External dependencies	See MIDI_SD and DLS.
Technical protection considerations	None known to the compilers of this document.

Quality and functionality factors

Normal rendering for sound	Not applicable; see MIDI_SD and DLS.
Fidelity (support for high audio resolution)	Not applicable; see MIDI_SD and DLS.
Support for multiple sound channels	Not applicable; see MIDI_SD.
Support for downloadable or user-defined sounds, samples, and patches	Yes, when an XMF instance contains or references DLS.
Functionality beyond normal rendering for sound	The XMF specification (RP-032) discusses Meta-Events pertaining to assignment of data to instruments in an XMF context. See also MIDI_SD; the compilers of this document have not investigated the degree to which such added functionality is provided by XMF as distinct from other file formats and/or application software.

File type signifiers

Tag type	Value	Note
Filename Extension	xmf	Suggested by the specification; not listed at The File Extension Source.
Internet Media Type	None identified.	A related type for mobile telephones is identified at http://www.iana.org/assignments/media-types/audio/vnd.nokia.mobile-xmf: vnd.nokia.mobile-xmf
Magic numbers	None identified

Notes

General

From http://www.wordiq.com/definition/MIDI: "The MIDI Association has now defined a new format, XMF (eXtensible Music File) which packages SMF (Standard MIDI File) format data with downloadable sounds, to much the same effect as MOD files. In spite of its name, XMF is not XML-based." From http://www.iana.org/assignments/media-types/audio/vnd.nokia.mobile-xmf: "Mobile XMF is a Musical Instrument Digital Interface (MIDI) specification developed by MMA [MIDI Manufacturers Association] and AMEI [Association of Musical Electronics Industry]."

History

The development of XMF post-dates that of RMID, the use of which is deprecated at the MIDI.org web site.

Format specifications

URLs

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• XMF Specification (2001), available for purchase from MIDI.org (http://www.midi.org/about-midi/specshome.shtml)

Useful references

URLs
• See MIDI_SD.
• http://www.wordiq.com/definition/MIDI, a short description.
• http://www.iana.org/assignments/media-types/audio/vnd.nokia.mobile-xmf, about Mobile XMF
• Gary Kessler's File Signatures Table (http://www.garykessler.net/library/file_sigs.html).
• The File Extension Source (http://filext.com/)

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