Tetorica FM2612 (hello_ymfm_wasm)

Small browser-side demos, documentation, and reusable code for YM2612, ymfm, WebAssembly, and VGM playback.

Open For AI documentation

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.

Tetorica Tools (Genesis / Mega Drive)

YM2612 Playground Try a small JavaScript playground with play(), beat(), liveLoop(), and raw fm access. Try with Nuked-OPN2 →

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

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 Tools (Experimental: PC-98, Neo Geo)

Experimental OPN-family FM modes and a MIDI live coding app for macOS. Genesis / Mega Drive support remains the project's primary goal.

PC-98 Sound: YM2608 Experimental YM2608 FM mode for PC-98 style sound. FM is available now; SSG, Rhythm, and ADPCM-B will be added as dedicated APIs. Open PC-98 YM2608 Playground →

PC-98 Sound: YM2203 Experimental three-channel YM2203 FM mode for earlier PC-98 compatible sound. Open PC-98 YM2203 Playground (3 FM channels) →

Neo Geo Sound: YM2610 Experimental four-channel YM2610 FM mode for Neo Geo style sound. SSG and ADPCM-A/B will be added as dedicated APIs. Open Neo Geo YM2610 Playground →

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.

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

Demos

YM2612 Beep Demo Play the same YM2612 beep configuration used in ex03_beep.cpp. Sega PSG Demo Play a minimal Sega PSG / SN76489-compatible tone through WebAssembly. YM2612 VGM Parser and Playback Demo Load a VGM file, inspect the header, preview parsed YM2612-oriented commands, and play it through WebAssembly. 1 Operator Demo Change one audible operator first: MULTI, TL, AR, RR, and pitch. 2 Operator Demo Compare parallel and serial relationships, then add feedback to operator 1.

Sega Genesis / Mega Drive YM2612 FM Introduction with JavaScript

The YM2612 is the FM sound chip used in the Sega Mega Drive / Genesis. This repository focuses on learning the chip, understanding how ymfm exposes it, and replaying it in the browser.

Start here if you want pin notes, beep-oriented register notes, or VGM basics in browser-readable pages.

Introduction What FM synthesis and the YM2612's operators/algorithms actually do, with a live Playground embedded. Tutorials Learn how to use the YM2612 and related technologies. Info Hub Open the browser-side reading hub for YM2612, FM, and VGM notes. YM2612 Basics Read the minimum path from pins and ports to a simple beep. YM2612 Basics (JA) 日本語で YM2612 の基本と beep までの流れを読む。 VGM Basics Learn what VGM stores and which YM2612-related commands matter first.

Embed YM2612 WASM in Web Apps and Games

This repository provides browser-side YM2612 and Sega PSG WASM files, JavaScript wrappers, a YM2612 synth layer, VGM playback support, a Genesis audio engine, and AudioWorklet-based output paths for Web sites, Web apps, and browser games.

Start here if you want to understand the runtime and embed YM2612 sound into a browser app or game.

Available Files

The browser-side implementation is split into small layers so that each part can also be used independently.

Releases: https://github.com/kyorohiro/hello_ymfm_wasm/releases

GitHub Releases is the primary download entry point for packaged wasm and browser-side runtime files.

web_runtime is this embeddable runtime, source file by source file (the files listed below). web_runtime_exsample is a runnable embedding sample bundle (the same runtime plus a few HTML demo pages) for a quick look at it working.

generated/ym2612_wasm.js / generated/ym2612_wasm.wasm — Emscripten-generated YM2612 / ymfm WebAssembly module.
generated/segapsg_wasm.js / generated/segapsg_wasm.wasm — Emscripten-generated Sega PSG WebAssembly module.
js/ym2612.js — Low-level JavaScript wrapper around the YM2612 WASM module.
js/segapsg.js — Low-level JavaScript wrapper around the Sega PSG WASM module.
js/ym2612synth.js — Small synth API for controlling YM2612 channels, operators, algorithms, notes, and register writes.
js/ym2612vgm.js — YM2612-specific helpers used by the VGM playback path.
js/vgmplayer.js — VGM parser and playback control layer.
js/genesisaudioengine.js — Genesis audio runtime combining YM2612 and Sega PSG playback.
js/ym2612-worklet.js — AudioWorklet processor that runs the YM2612 WASM synthesizer on the audio rendering thread.
js/megasynth.js — MegaDriveSynth: a batteries-included wrapper combining YM2612Synth, the FX chain, the looper, and recording behind one AudioWorklet-backed API.
js/megasynth_fx.js — Browser-side FX chain (gain, EQ, filter, delay, reverb) for use with MegaDriveSynth or standalone.
js/megasynth_recording.js — Records and replays MegaDriveSynth commands as JSON for the event-record and looper features.
js/looper.js — Lightweight musical-event looper for MegaSynth / YM2612 browser usage.
js/megadrive-fm-presets.js — Ready-made YM2612 FM instrument presets.
js/tfi.js — TFI (OPN2 patch) import/export helpers for YM2612Synth presets.
js/vgi.js — VGI (VGM Maker) import/export helpers for YM2612Synth presets.

Examples and Documentation

YM2612Synth TFI / VGI import demo →

YM2612 WASM Usage Learn the minimum path from generated files to JavaScript control. VgmPlayer Usage Learn how the current higher-level browser-side VGM player is structured. AudioWorklet Usage Learn how the browser demo feeds rendered chunks into AudioWorklet output. YM2612Synth Direct Demo Learn how to use YM2612Synth with YM2612DirectTransport to generate PCM directly from the YM2612 WASM wrapper. YM2612Synth AudioWorklet Demo Learn how to use YM2612Synth with YM2612WorkletTransport to generate PCM through AudioWorklet. MegaDriveSynth Embedded Demo Learn how to use MegaDriveSynth Playground Runtime Embedded Demo Learn how to move Tetorica-style live code into a browser game or app. VGM Runtime Embedded Demo Learn how to embed YM2612 + PSG VGM playback as a small browser-side runtime.

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