IMF vs MIDI: id Software AdLib OPL2 Register Stream vs Standard MIDI
Compare id Software's IMF music format with standard MIDI: Yamaha YM3812 FM register commands, tick timing, and soundcard hardware emulation.
IMF directly stores raw byte pairs written to the PC's AdLib/Sound Blaster Yamaha YM3812 (OPL2) FM synthesis chip at fixed timer intervals, whereas MIDI transmits abstract musical notes, velocities, and instrument patch commands meant for general synthesizers.
| FEATURE | IMF | MIDI |
|---|---|---|
| Sound Generation | Hardware OPL2 register-data writes | Abstract note & control change events |
| Synthesizer Hardware | Yamaha YM3812 (OPL2 FM Synthesis) | Any synthesizer / SoundFont / WaveTable |
| Tick Rate | 560 Hz (Wolf3D) or 700 Hz (Keen) | PPQ (Pulses Per Quarter Note) |
| File Size | Extremely compact (few kilobytes) | Compact (few kilobytes) |
| Hardware Independence | Tied directly to AdLib FM architecture | Platform and hardware agnostic |
- Exact reproduction of authentic 1990s MS-DOS FM synthesizer instruments
- Bit-exact AdLib timbre without reliance on generic SoundFont soundbanks
- Extremely low CPU and memory footprint for early 286/386 PC gaming
- Native soundtrack format for Wolfenstein 3D, Commander Keen, and Duke Nukem II
- Universal music standard supported by modern digital audio workstations (DAWs)
- Instrument patch independence (General MIDI soundbanks, Roland SC-55, Yamaha MU)
- Direct editing of notes, pitches, velocities, and tempo tracks
- Wide hardware synth and software soundfont ecosystem
MIDI is the universal composition standard, but IMF captures the exact nostalgic FM synthesis timbre of classic id Software PC games. convrtr emulates the Yamaha YM3812 OPL2 chip in-browser to render IMF files directly to 16-bit stereo WAV.
Converting files between IMF and MIDI frequently? The convrtr Chrome Extension lets you right-click any image on any webpage or open the Side Panel to convert assets instantly using local WebAssembly with zero server uploads.