Free online XMI to FLAC converter

Programs such as modern audio editors and media players generally do not open XMIDI files directly, while FLAC is widely supported for lossless audio playback and archiving. Converting an XMI file therefore requires first turning its musical events into MIDI and then rendering those events with a synthesizer.

What the XMI format is

In the Audio category, XMI means Extended MIDI, also called XMIDI. It is a MIDI-event container used extensively by DOS games and older multimedia software, especially titles using the Miles Sound System or similar game-audio engines.

An XMI file normally stores note events, instrument changes, controller data, tempo information, and timing instructions rather than recorded waveform samples. Games and legacy music tools created XMI files because XMIDI supports playback features such as delayed events and efficient looping. You may encounter it in extracted game music, archival software collections, and old game-development projects.

What the FLAC format is

FLAC is a lossless codec for PCM audio. It reduces file size without discarding audio data, and the decoded samples are identical to those in the source WAV file.

FLAC is suitable for music archiving, editing workflows that accept lossless audio, and playback on software and hardware with FLAC support. Unlike XMI, FLAC contains rendered sound, so its contents depend on the synthesizer, SoundFont, instrument samples, effects, tempo interpretation, and output settings used during conversion.

How to actually convert XMI to FLAC

Because XMI contains performance instructions instead of a finished recording, use a two-stage process: convert XMI to standard MIDI, then render the MIDI to audio.

1. Install an XMI-to-MIDI utility such as xmi2mid. Use the utility's conversion command, for example xmi2mid input.xmi output.mid. If the file contains several songs, the program may produce multiple MIDI files; process the intended sequence separately.
2. Install FluidSynth and obtain a General MIDI SoundFont, such as a legally redistributable .sf2 file. The SoundFont supplies the instrument sounds that XMI itself usually does not contain.
3. Render the MIDI to an intermediate WAV file with FluidSynth:

fluidsynth -ni soundfont.sf2 output.mid -F output.wav -T wav -r 44100

4. Encode the rendered WAV as FLAC using FFmpeg:

ffmpeg -i output.wav -c:a flac output.flac

After checking the FLAC, remove the intermediate WAV if it is no longer needed. A desktop workflow can use any XMI-to-MIDI converter, FluidSynth with its graphical front end, and an audio encoder; there is no standard audio-editor command that can directly interpret every XMI variant.

For a no-installation workflow, the built-in converter on 101convert.com can convert the file online for free, subject to the site's supported XMI variants and file-size limits.

Quality, compatibility, and limitations

FLAC compression is lossless only after rendering; it cannot preserve the original XMI event structure or reproduce an original game soundtrack that used a different synthesizer. The selected SoundFont can change instruments, drum mappings, articulation, stereo placement, volume, and overall character.

Use the same SoundFont and a sample rate such as 44100 Hz for repeatable results. If the result is silent or uses incorrect instruments, inspect the MIDI program changes and select a SoundFont with General MIDI drum and instrument mappings. Some game engines applied custom effects, looping rules, pitch behavior, or proprietary patches that ordinary XMI-to-MIDI tools cannot reproduce.

Keep the original XMI and converted MIDI alongside the FLAC when archiving. The MIDI remains useful for changing the SoundFont or re-rendering the music, while the FLAC preserves only the particular audio interpretation produced by the chosen synthesizer.