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  • The Official MIDI Specifications

    The Official MIDI Specifications

About Mobile XMF

About Mobile XMF

Reprinted courtesy of and (C) 2004 Beatnik, Inc

Mobile XMF is an open standard audio format that bundles a tiny Scalable-Polyphony MIDI (SP-MIDI) file, custom instrument samples (Mobile DLS), and copyright information all in one deliverable package.

Every major region of the global wireless market has accepted polyphonic ringtones as a must-have feature. Mobile XMF pushes the polyphonic trend to the next level with the addition of compact custom sound samples. Now composers and carriers alike can differentiate their content from competitors with sonically branded styles, yet be assured that every song will play back as intended on al Mobile XMF-enabled devices.

Custom Sounds and Compressed Samples

Mobile XMF uses Mobile DLS (Mobile Downloadable Sounds) to provide wavetable synthesis in resource-constrained environments. Based on the music industry "DLS2" format (which is also included in MPEG-4 Structured Audio), Mobile DLS offers a subset of DLS2 functionality, while introducing new features suitable for mobile devices, such as sample compression. Including Mobile DLS in a Mobile XMF means customizing a song with anything from drum loops to vocal phrases, giving common polyphonic music a completely new sound. Mobile DLS also supports sample compression which makes files even smaller by compressing the already small WAV files in each instrument. This makes Mobile XMF files perfect for transmitting over narrow-bandwidth networks.

Consistent Playback

Mobile XMF defines what a file should sound like when played on a compatible device, taking into account polyphony constraints. For composers, it means less work and guaranteed quality since any standard Mobile XMF file will render consistent playback on all Mobile XMF-enabled devices. Game and application developers will experience the same benefits from Mobile XMF as ringtone providers. With one file, an application can use custom music containing digital samples. Regardless of the the playback device, the game’s music and sound effects will play as the composer intended.

Rights Meta-data

The ability to attach metadata gives composers and content distributors a mechanism to publish the recording and distribution rights inside the actual file. Mobile XMF offers a convenient, secure way to bring unique content to customers.

Mobile XMF/DLS Features & Benefits

  • Standards-Based
MMA/AMEI & 3GPP standard. Positioned for wide proliferation of content wth consistent playback on any platform.
  • Unique Custom Sounds
Mobile DLS included in file. Composers can add small samples of anything from drum loops to vocal samples.
  • Scalable
SP-MIDI provides the musical "score". Compose once, plays as expected on many different devices.
  • Mixes Multiple Audio Types
Combines recorded audio and SP-MIDI in a single file. Rich Audio experience with more options for mixing mulitple audio types.
  • Metadata
Each Mobile XMF file contains metadata fields Gives composers and publishers a way to tie authoring and copyright data to each file.


The Mobile XMF Specification is included in the XMF Specification 1.2 Document.