SoundFont2 based realtime synthetizer and MIDI player written in JavaScript using Web Audio API. Can also be used as a synthesis library.

Live demo

Youtube video

This repo is essentially 2 programs in one:

spessasynth_lib

A flexible, powerful, and feature-packed soundfont synthesizer library for the WebAudio API.

Tip

Looking for a Node.js version? try spessasynth_core

Documentation

Features

• SoundFont2 Generator Support
• SoundFont2 Modulator Support
• SoundFont3 (vorbis compressed sf2) Support (thanks to stbvorbis.js)
• • Can provide very hiqh quality audio while being relatively light on file size thanks to sf3 support
• Reverb and chorus support
• Render audio to file
• A few custom modulators to support some additional controllers (see modulators.js)
• Written using AudioWorklets (Firefox and Chrome both work perfectly)
• Can load really large soundfonts (4GB!) (but only on Firefox, Chromium has a memory limit)
• Multi-port MIDIs support (more than 16 channels)
• MIDI Controller Support (Default supported controllers can be found here).
• Supports some Roland GS and Yamaha XG sysex messages
• High performance mode for playing black MIDIs (Don't go too crazy with the amount of notes though)
• Can be used as a library (learn more here)
• Modular design allows easy integrations into other projects
• Written in pure JavaScript using WebAudio API (Every modern browser supports it)
• No dependencies

Limitations

• The performance is questionable, especially on mobile devices.

Installation

1. Clone this repository.
2. copy src/spessasynth_lib to your project.
3. Use the library

Web app / Local Edition

The complete GUI for spessasynth_lib, allowing remixing experimenting and playing MIDIs in the coolest way possible.

How to use

Features

• Visualization of the played sequence with effects like visual pitch bend and note on effects
• Playable keyboard with various sizes
• Integrated controller for the synthetizer with a lot of options
• Mutliple languages support, currently: english, polish, japanese
• Web MIDI API support (Enables physical MIDI devices to be used with the program)
• WebMidiLink support
• Play around with the MIDI file, edit instruments controllers and more!
• Render the MIDI file (either modified or unmodified) to wav
• Comes bundled with a compressed SGM SoundFont to get you started

Installation

Important

Firefox is recommended, due to unconstrained memory size.

Recommended high quality soundfont (better than the built-in one)

Requires Node.js

Windows

1. Download the code as zip and extract or use git clone https://github.com/spessasus/SpessaSynth
2. Put your soundfonts into the soundfonts folder. (you can select soundfonts in the program)
3. Double click the start.bat
4. Enjoy!

Linux

1. git clone https://github.com/spessasus/SpessaSynth
   cd SpessaSynth
   npm install && node server.js 

2. Put your soundfonts into the soundfonts folder. (you can select soundfonts in the program)
3. Enjoy!

(note that in KDE Plasma 6 the browser auto opening seems to be broken. You must navigate to http://localhost:8181 manually)

todo

• make the worklet system perform good
• port the worklet system to emscripten (maybe)

Special thanks

• Fluidsynth - the source code really helped me understand and implement a lot of functionality and fixes
• Polyphone - a wonderful testing tool for soundfonts and how they should sound
• Meltysynth - for the low-pass filter implementation
• You! - for checking out this project. I hope you like it :)

License

Copyright © 2024 Spessasus. Licensed under the MIT License.

Important

Please note that bundled stbvorbis_sync.js licensed under the Apache-2.0 license.