Tetorica FM2612 (hello_ymfm_wasm)

Tetorica is a tool for live coding retro game sounds in JavaScript, including the sounds of the Sega Genesis / Mega Drive and Game Boy.

Goals

This repository has four goals:

To understand the YM2612 chip.
To create documentation that helps anyone understand the YM2612 chip.
To create documentation that helps anyone embed YM2612 audio in a browser app or game.
To preserve older game music and sound chip technology as cultural heritage that people today can read, investigate, learn from, and reconstruct—not only archive and play back.

This repository also provides YM2612 WebAssembly modules and JavaScript interfaces for browser-side use.

Repository: https://github.com/kyorohiro/hello_ymfm_wasm

These demos use ymfm by Aaron Giles under the BSD 3-Clause License.

npm Packages

Use Tetorica in your own projects: analyze existing VGM music with tetorica-vgm, or build sound-chip audio with tetorica-fm2612. Node.js usage requires Node.js 22 or later.

VGM tools · Node.js CLI / API

tetorica-vgm

Analyze VGM/VGZ files, export scores and FM voices, and render WAV audio. Use the command line or import the analysis and export APIs into a Node.js application.

npm install tetorica-vgm
npx tetorica-vgm analyze song.vgz --json

npm → Usage & Node API → CLI reference →

Sound-chip audio · Browser / Node.js

tetorica-fm2612

Import sound-chip cores and synth APIs as ES modules with prebuilt WASM. Generate PCM in Node.js, or add FM, PSG and PCM audio to a browser app with the included Web Audio runtime.

npm install tetorica-fm2612

Includes YM2612, related Yamaha chips, Sega PSG, RF5C164 and other sound chips. Start with createSoundChip, YM2612Synth or MegaSynth.

npm → Web & Node.js examples →

Native C++ / WASM Sources

Reusable sound-chip sources · C/C++ / WebAssembly

tetorica-soundchip-native

Build sound-chip audio into your own application with C/C++ cores, native adapter sources and WebAssembly build recipes collected in one repository. Component licenses, source provenance and local modifications are documented alongside the code.

The standalone native build currently supports YM2612 (ymfm). Other chip adapters are included as reference sources, with their build requirements and backend differences documented.

Source repository → Build & integration guide →

Tetorica Tools (Experimental)

YM2612 Playground Try a small JavaScript playground with play(), beat(), liveLoop(), and raw fm access. Try with Nuked-OPN2 → PC-98 YM2608 Playground → PC-98 YM2203 Playground → Neo Geo YM2610 Playground →

YM2612 Synth Demo Try a small YM2612Synth keyboard with a guitar-like PC key layout and preset switching. Try with Nuked-OPN2 →

Tetorica SCSP Synth

Sega Saturn PCM synthesizer. Draw or import a waveform, edit the envelope, play chords, and save PCM presets.

Tetorica SPU Synth

PlayStation 1 SPU synthesizer / emulator. Draw PCM waveforms, shape ADSR envelopes, add SPU reverb, and play with a guitar-style keyboard.

Tetorica DMG Synth

Play Pulse, Wave and Noise on one Game Boy DMG APU. Draw a waveform, shape envelopes and Sweep, then save a preset or take the instrument away as JavaScript.

Tetorica 2A03 Synth

Play Pulse, Triangle, Noise, DMC and FDS with hardware envelopes, Pulse / Triangle / Noise counter gates and live chip-state meters. Draw DMC target curves or edit bits with DAC preview and Undo / Redo, draw FDS waves and modulation, import settings and recorded DMC samples from VGM / VGZ, then save presets, export DPCM or copy JavaScript.

Tetorica HuC6280 Synth

Play the PC Engine’s wavetable PSG, Noise and paired LFO. Draw waves, load audio as five-bit DDA PCM, or import Wave / Noise / LFO / DAC-stream and direct-DAC PCM sounds from VGM / VGZ. Save and reuse your sounds.

Tetorica S-DSP Synth

Play eight SNES BRR / hardware Noise voices or four-note hardware PMON. Draw a Wave or preview a BRR modulator on one canvas, with independent tuning / ADSR / GAIN and Echo / FIR. Import SPC voices or optional PMON pairs; load audio / BRR into either sample. Save both samples in v5 presets or copy JavaScript.

Tetorica SID Synth

Explore SID 6581 / 8580 Preview with three voices, Pulse width, hardware ADSR and a shared filter. Combine LP / BP / HP, try a one-note Sync / Ring pair, save presets or take the readable JavaScript. Experimental PAL approximations.

SID Player

Open a supported PAL PSID or RSID tune with Auto / 6581 / 8580 Preview model selection. Watch voice and filter settings. VBI / CIA interrupts run in the C64 machine with safe driver RAM and a limited built-in environment or your own ROMs. Direct VBI is a 6581 option. Original demos included.

FM2612 VGM Analyzer Inspect parsed commands, watch 6 YM2612 channels, and export snapshot data or TFI patches. Sound chip support → Try with Nuked-OPN2 →

Tetorica MIDI Playground Live-code MIDI melodies and loops in JavaScript. Connect this macOS app to GarageBand, a DAW, or a MIDI instrument. Download for macOS → View on itch.io →

Introduction

Sega Genesis / Mega Drive YM2612 FM Introduction with JavaScript New here? Start with what FM synthesis and the YM2612's operators/algorithms actually do, with a live Playground embedded right in the page.

Sega Genesis / Mega Drive Sega PSG Introduction with JavaScript Compare square waves, three-note chords, and noise with editable JavaScript examples.

Sega Mega CD RF5C164 Introduction with JavaScript Play custom waveforms from RAM and explore PCM by changing playback rate, volume, and stereo output.

Just Intonation and Equal Temperament with JavaScript and Sega Genesis / Mega Drive YM2612 Start with one frequency, build intervals from simple ratios, and hear the difference between just intonation and equal temperament directly on the YM2612.

From Sound Chip to Beep: YM2612 in JavaScript Learn how registers control the YM2612, then edit and run a simple beep in the embedded Playground.

FX Introduction with JavaScript — Work in progress Explore 15 draft FX lessons, from Gain to Reverb and effect chains, with editable Playground examples.

Game Boy 01 — Pulse: Compare Pulse Waves Change duty cycle, pitch, and volume, compare the sound and PCM waveforms, and take your settings home as JavaScript. Game Boy 02 — Envelope: Shape Volume over Time Adjust starting volume, direction, and period, then hear the envelope and inspect the generated PCM amplitude. Game Boy 03 — Wave: Draw and Play a 32-Sample Waveform Edit triangle and sawtooth waveforms, copy and paste their arrays, and continue editing in the Playground.

SID Filter — Change the Brightness of a Sound Keep one Saw note playing, compare filter outputs and the spectrum, route three voices through one shared filter, then edit the same settings as JavaScript.

Embed Sound Chips in Web Apps and Games

Learn how to use the tetorica-fm2612 npm package through small, complete examples. Explore direct chip control, AudioWorklet output, MegaSynth with FX, event recording and looping, Playground embedding, VGM playback, and TFI / VGI instruments.

tetorica-fm2612 Examples Run browser demos, read complete Web and Node.js source, and learn how the runtime fits together.

References

ymfm, libymfm.wasm, MAME, retropc.net, YM2612 pin reference, VGMPF YM2612, SpritesMind thread, chipmusic YM2612, DefleMask, GENajam, megatoy, Maple's Garden article, Aidan Lawrence's Sega Genesis video game music player, Zophar's Domain Genesis Music, SMS Power