What is the XMF file format?
.xmf files use the eXtensible Music Format, an open binary audio container standard developed by the MIDI Manufacturers Association (MMA) and the Association of Musical Electronics Industry (AMEI) in 2001. XMF solves a fundamental limitation of standard MIDI files: because MIDI playback depends on the synthesizer hardware present on the device, the same sequence can sound completely different on different systems. An .xmf file bundles the MIDI sequence together with its DLS (Downloadable Sounds) instrument definitions in one self-contained container, guaranteeing consistent playback across hardware.
The format uses a tree-structured binary layout identified by the four-byte magic signature XMF_ at offset 0. Three main types exist:
- Type 0 - MIDI + DLS, fully streamable
- Type 1 - MIDI + DLS, must be fully loaded before playback
- Type 2 (Mobile XMF /
.mxmf) - compact variant designed for mobile phones; standardized by IETF RFC 4723 (2006)
Mobile XMF was widely deployed on Nokia, Sony Ericsson, and other feature phones between 2003 and 2007 for ringtones and game audio. With the rise of iOS (2007) and Android (2008), hardware MIDI synthesis was dropped from smartphones and XMF became largely obsolete, replaced by AAC and MP3.
Note that the .xmf extension is also used by the Cal3D open-source 3D animation library for an unrelated XML mesh format, which can cause confusion.
Security & safety
RISK: LOWXMF files contain MIDI sequences and audio data; no executable code. Standard media file risks only (malformed files causing player crashes).
Format details
in a nutshell- Cal3D XML Mesh File - The Cal3D 3D character animation library uses .xmf for XML-based mesh data - entirely unrelated to audio.
- CDRWin Virtual CD image (incorrect association) - CDRWin uses .cue, .bin, .img for disc images; the .xmf association in CDRWin is erroneous and appears in legacy databases.
Programs that open XMF files
Windows3 apps
IMVU
Free IMVU uses XMF internally for avatar audio; end users do not directly open .xmf files in IMVU. 
VLC media player
Open-source File → Open File - VLC can play XMF/MXMF files via its MIDI/audio engine (FluidSynth backend may be needed for DLS instruments). 
Foobar2000
Free Install foo_midi plugin (foobar2000 component); then open .xmf file - plugin handles MIDI and DLS decoding. 
macOS1 app
Linux2 apps
VLC media player
Open-source vlc yourfile.xmf - install fluid-soundfont-gm for DLS instrument rendering. 
Cal3D (open-source 3D library)
Open-source Note: Cal3D's .xmf is an XML mesh file, NOT audio - completely different format. Technical details
deep spec| Encoding | Binary |
| Byte order | Big-endian |
| Container structure | Tree-structured with root and child nodes; node offsets encoded as Variable Length Quantities (VLQ) |
| Magic bytes | XMF_ (hex 58 4D 46 5F) at offset 0, followed by version string (e.g. XMF_1.00, XMF_2.00) |
| MIME type | audio/xmf (Type 0/1); audio/mobile-xmf (Type 2 / Mobile XMF, IETF RFC 4723) |
| Supported embedded data | Standard MIDI Files, DLS soundfonts, WAV audio, and metadata nodes |
| Format types | Type 0 (streamable MIDI+DLS), Type 1 (non-streamable MIDI+DLS), Type 2 (Mobile XMF - compact, for mobile devices) |
| Sample rate (embedded audio) | Depends on embedded DLS/WAV content; typically 22,050 Hz or 44,100 Hz |
| Compression | None at container level; embedded DLS or WAV data may carry internal compression per spec |
| Typical file size | 5 KB - 2 MB (MIDI-only); up to 10 MB+ with embedded audio samples |
| Standard body | MIDI Manufacturers Association (MMA) and Association of Musical Electronics Industry (AMEI) |
| Mobile deployment era | 2003-2007 on Nokia, Sony Ericsson, and J2ME feature phones for ringtones and game audio |
| Extension conflict | .xmf also used by Cal3D 3D animation library for an unrelated XML mesh format |
| Released | 2001 (XMF 1.0 specification adopted by MMA) |
| Latest version | XMF 1.1; Mobile XMF Type 2 (IETF RFC 4723, 2006) |
| Open standard | Yes · royalty-free |
| Specification | www.midi.org |
XMF conversions
Community Q&A
asked by usersNo questions yet - be the first to ask about XMF files.
