Recomposer MIDI Sequencer music file
File type: Audio and sound file
A .g18 file is a MIDI sequence file used by Recomposer MIDI Sequencer. It stores musical performance data rather than recorded audio.
The format is associated with sequencers in Come On Music's Recomposer product series.
File type category:
Audio and sound file
Date updated: November 4, 2026
The .g18 file extension identifies a MIDI sequence format used by some sequencers in Come On Music's Recomposer series. These products were particularly known in Japan, where this format was widely used for MIDI sequence data.
A .g18 file contains sequence information for music playback, such as the musical events and their timing, rather than an audio recording. It is an alternative to the smf format.
Some free MIDI sequencers can also handle Recomposer sequence files.
Open a .g18 file with a compatible version of Recomposer MIDI Sequencer or another MIDI sequencer that explicitly supports the Recomposer format. Because the format is associated with older software, the original program may require its supported legacy operating environment.
Ordinary media players and MIDI applications that support only SMF files generally cannot open a .g18 file directly.
If a compatible Recomposer sequencer can open the file, use its MIDI export or save option to create a Standard MIDI file (SMF), when available. The resulting SMF can then be used by a wider range of MIDI software.
There is no dependable general-purpose conversion method for .g18 files without software that understands the Recomposer format.
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