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XMF - eXtensible Music Format XMF Specifications
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XMF is a family of music-related file formats created and administered by the MIDI Manufacturer's Association. XMF is based on the idea of containing one or more existing files – such as Standard MIDI Files, DLS instrument files, WAV or other digital audio files, etc. – to create a collection of all the resources needed to present a musical piece, an interactive web page soundtrack, or any other piece of media using pre-produced sound elements.

There are two parts to XMF: the XMF Meta-File Format, which all XMF files use, and a series of XMF File Types that use the XMF Meta-File Format for various purposes.

XMF Meta-File Format (RP-030) – XMF is designed to keep file sizes as small as possible, in order to be useful on systems ranging from small-footprint mobile devices like cell phones to desktop/laptop computers to high-power web servers. It also has no maximum file size, so it could be used to store very large collections if desired. To support international music data commerce, the meta-data that travels with the resources can be International, keyed to the user's language and the country in which playback is happening – so in an XMF album, the liner notes could change language depending on who's listening.

Revision History

  • XMF Meta File Format 1.01 Update (RP-039)

Some fixes and enhancements resulting in Version 1.01 of the XMF Meta File Format and Type 0/1 XMF files. The XMF 1.01 Update (pdf) to the 1.0 Specification is available for free download.

  • XMF Meta File Format 2.00 Update (RP-043)

This change to the header format makes it easier to assign MIME Media Types to new XMF File Types, starting with Mobile XMF. The XMF 2.00 Update (pdf) to the 1.0 Specification is available for free download.

XMF File Types

XMF Type 0 and XMF Type 1 Files (RP-031) contain Standard MIDI Files that can use General MIDI instruments (provided by a player), and custom DLS instruments (provided in the XMF File). The MIDI files and the DLS files are bound together in the XMF file, rather than traveling separately where they can get lost. Type 0 and Type 1 are identical, except that in Type 0 the MIDI data may be streamed.

XMF Type 2 Files are also called Mobile XMF Files (RP-042). Mobile XMF (Type 2) was developed specifically for mobile phones, and supports SP-MIDI format SMF files as well as Mobile DLS content. It uses the new version 2 Meta File Format specification, which enables MIME Type support.

XMF Type 3 Files are also called Audio Clips for Mobile XMF Files (RP-045). XMF Type 3 makes XMF a rich recorded music format by allowing digital audio clips to be placed on the MIDI timeline (not just MIDI instruments). The audio clips can use various codecs (if registered with MMA/AMEI), and the files can include ID3 metadata (like MP3). Additionally, if Mobile Phone Control messages are included (see RP-046), XMF Type 3 content can use MIDI to control LEDs, vibras, and other non-audio output devices.

XMF Type 4 files are called Interactive XMF (iXMF) files. Interactive XMF is the world's first open format for interactive audio content.

XMF Enhancements

XMF Registered IDs

The XMF Specification defines XMF UnPackerIDs and ResourceFormatIDs that may only be obtained from the MMA, and must be registered before use, to prevent collision with other XMF implementations. The official public list of Registered IDs is available on this web site and updated continuously as new IDs are assigned. To apply for an XMF Registered ID, please contact us.

Document Publication Information

Buy Now: "XMF Specification" (RPs 030-032, 039, and 040) Document

Buy Now: "Mobile DLS/XMF Specification" (RPs 041-043) Document

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