OMI

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Origin MIDI
OMI.png
Developer: Herman Miller
Header: Custom
Content: Notational
Instruments: External
Target Output
Output - Digital Audio - No.png Output - MIDI.png Output - FM Synthesis.png Output - PSG - No.png
Released: 1990-09-26
First Game: Wing Commander (DOS)
Extensions
  • *.omi

Origin MIDI (OMI) is an audio format created by Herman Miller and was used in the Wing Commander and Worlds of Ultima games of the early 1990s. The format stores game music and can be sent to various output devices including AdLib, Sound Blaster, and Roland MT-32. Instrument data for each device is stored in a TIM archive file and the audio driver is STRAX.DRV. The actual music files from the game do not have a file extension; OMI is used to help distinguish the format since it is similar enough in structure to be confused with MIDI, but different enough to prevent most MIDI players from playing it. Like MIDI, OMI allows for meta data including song and track titles, however, not every composer added them.

Miller explained his design of the format:

Basically it was based on a MIDI format because the files we were getting from the composer were MIDI. It also had some control characters to mark sections that weren't part of the MIDI format but I don't remember details. I believe it was originally destined for Ultima VII, while other teams were working on Worlds of Ultima and Wing Commander at the same time, but at some point during Ultima VII development we switched to the Miles sound system.

Although the Worlds of Ultima games use the same engine as Ultima VI: The False Prophet (DOS), they use this new audio format instead of the earlier M format. Subsequent Origin games used John Miles's XMI format.

Players

(Category)

Currently there are no players that support this format.

Games

(Category)
Released Title Sample
1990-09-26 Wing Commander (DOS)
1990-??-?? Worlds of Ultima: The Savage Empire (DOS)
1991-??-?? Ultima: Worlds of Adventure 2 - Martian Dreams (DOS)
1991-??-?? Wing Commander II: Vengeance of the Kilrathi (DOS)
1993-??-?? Wing Commander Academy (DOS)

How to Obtain

The files must be extracted from the each game's LZC compressed music data files.

Technical

Like a MIDI file, each OMI file begins with "MThd" and contains "MTrk" at the start of each track. Meta data is allowed in each track to identify the instrument or give a title. The format also has non-standard MIDI control codes which are used to help keep the music in sync with the game.

You can study the format by using the unpack_lzc.exe tool created by the Nuvie team.

Links