DX7

A Yamaha DX7 FM synthesizer emulator in Rust.

Demo

E.PIANO 1 solo — "Greatest Love of All" intro (DX7's iconic FM electric piano):

https://github.com/knoguchi/dx7/raw/main/demo/epiano1_intro_demo.mp4

Structure

• dx7-core — Platform-independent synthesis engine (no-std capable, zero dependencies)
• dx7-app — CLI application with real-time audio, MIDI input, keyboard control, and MIDI file rendering

Build

cargo build --release

Usage

Interactive mode

Play with computer keyboard or a connected MIDI controller:

cargo run --release --package dx7-app

Keyboard controls:

• ASDFGHJKL; — white keys (C4-E5)
• WETYUOP — black keys
• Z/X — octave down/up
• 1-9,0 — select patch
• Q/Esc — quit

Load patches from SysEx

cargo run --release --package dx7-app -- --sysex sysex/factory/rom1a.syx --patch 0

Render a single note to WAV

cargo run --release --package dx7-app -- --render output.wav --note 60 --velocity 100 --duration 3

Render a MIDI file to WAV

cargo run --release --package dx7-app -- --midi-file song.mid --sysex sysex/factory/rom1a.syx --patch 3 --render output.wav

GM mode

Render a MIDI file using the built-in General MIDI sound set (128 programs mapped to DX7 patches):

cargo run --release --package dx7-app -- --midi-file song.mid --render output.wav --gm

Use --track 1 --track 2 to render specific tracks only.

List MIDI ports

cargo run --release --package dx7-app -- --list-midi

SysEx Banks

The sysex/ directory contains DX7 patch banks organized by source:

• factory/ — 8 official factory ROM banks (ROM1A–ROM4B)
• vrc/ — 24 Voice ROM Cartridge banks (VRC101–VRC112)
• greymatter/ — Grey Matter E! expansion banks

Engine

• 6 identical FM operators with 32 algorithm topologies
• 24-bit phase accumulator, 10-bit sine ROM in log domain
• Integer log/exp domain math matching the YM21280 OPS chip
• Per-operator amplitude envelopes, pitch envelope, LFO
• 4th-order Butterworth output filter at 10.5 kHz (DX7 reconstruction filter)
• DC-blocking filter, stereo reverb, and soft saturation
• GM sound set with 128 programs and synthesized drum machine (channel 10)

Reference

• music-synthesizer-for-android (msfa) engine