@thinkridge/rlib-soundfont

SoundFont, FM, and PSG audio rendering for Web / Node.js, powered by WebAssembly.

Converts Standard MIDI Files (SMF) to WAV audio. Each track can be rendered through a SoundFont (.sf2), or through the built-in FM (YM2203/OPN) or PSG (SSG) chiptune synth engines — freely mixed within a single song.

Features

• Works in both Node.js and modern browsers
• Decode SoundFont (.sf2) files
• Convert SMF (MIDI) → WAV audio
• Built-in FM (YM2203/OPN) and PSG (SSG) synth engines, powered by the ymfm sound chip emulator
• SoundFont, FM, and PSG tracks can be freely mixed within a single SMF
• Powered by WebAssembly (fast and portable)
• No external runtime dependencies

Demo

• https://rlib-mml.thinkridge.jp/

  An interactive demo that lets you create, compile, and play MML entirely in the browser.
  Supports SoundFont, FM, and PSG based playback. No installation required.

Repository

• Monorepo root
  https://github.com/thinkridge/rlib-Sounds

• Package location (@thinkridge/rlib-soundfont)
  https://github.com/thinkridge/rlib-Sounds/tree/main/rlib-SoundFont/npmpackage

Installation

npm install @thinkridge/rlib-soundfont

Usage (Node.js)

import * as fs from "node:fs/promises";
import { RlibSoundfont } from "@thinkridge/rlib-soundfont";

const rlibSoundfont = new RlibSoundfont();
try {
  const sf2Binary = new Uint8Array(await fs.readFile("example.sf2"));
  const smfBinary = new Uint8Array(await fs.readFile("test.mid"));
  await rlibSoundfont.initSoundfont(sf2Binary);
  const wavBinary = await rlibSoundfont.smfToWav(smfBinary); // smf -> wav
} catch (e) {
  console.error(e);
} finally {
  rlibSoundfont.dispose();
}

Rendering SoundFont / FM / PSG tracks

No separate API is needed to use the FM/PSG engines — smfToWav() picks the renderer per track automatically, using the instrument named in each track's Track Name meta event (the same convention used by rlib-MML's CreatePort(instrument:...)):

• "fm" — rendered with the built-in FM (YM2203/OPN) synth engine
• "psg" — rendered with the built-in PSG (SSG) synth engine
• any other name (including the default, unnamed track) — rendered with the SoundFont passed to initSoundfont()

A single SMF can freely mix SoundFont, FM, and PSG tracks. Custom voice presets can also be embedded in the SMF via rlib-MML's DefinePresetFM() / DefinePresetPSG() meta events.

License

MIT © Thinkridge Co., Ltd.

Notes

This package's WebAssembly build is compiled from the C++ core at rlib-SoundFont/src, which includes a vendored copy of the ymfm FM/PSG sound chip emulation library (https://github.com/aaronsgiles/ymfm) under rlib-SoundFont/src/ymfm. ymfm is released under the BSD 3-Clause License, Copyright (c) 2021, Aaron Giles. See rlib-SoundFont/src/ymfm/LICENSE for the full license text.

Build

This package is published with prebuilt artifacts. End users do not need emsdk or Docker.