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

Youtube Video

• SoundFont2 Generator Support
• SoundFont2 Modulator Support
• Reverb and chorus support
• A few custom modulators to support some additional controllers (see modulators.js)
• Written using AudioWorklets (Firefox and Chrome both work perfectly)
• Legacy system that doesn't use AudioWorklets (Available to use over HTTP and will switch automatically)
• 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 and Yamaha XG sysex messages
• High performance mode for playing black MIDIs (Don't go too crazy with the amount of notes though)
• Visualization of the played sequence
• Playable keyboard with preset selection
• Integrated controller for the synthetizer
• Web MIDI API support (Enables physical MIDI devices to be used with the program)
• WebMidiLink support
• 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 (Node.js is only required for the app, the core synth and sequencer library needs no dependencies)
• Comes bundled with a small GeneralUser GS soundFont to get you started

• It might not sound as good as other synthetizers (e.g. FluidSynth or BASSMIDI)
• The modulation envelope needs some work
• the modulators need some work

When you're loading a large (>4GB) SoundFont, use Firefox because chromium has a 4GB memory limit

Requires Node.js

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!

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)

Note: the wiki is quite outdated, but most of the methods should still work.

The program is divided into parts:

• Soundfont2 parser - parses the soundfont file into an object readable by synth
• MIDI file parser - parses the midi file into an object readable by sequencer
• Sequencer - plays back the parsed MIDI file. Must be connected to a synthetizer. Can be connected to a renderer
• Renderer - renders the waveforms of the channels and the falling notes. Must be connected to a synthetizer
• Synthetizer - generates the sound using the given preset
• UI classes - used for user interface, connect to their respective parts (eg. synth, sequencer, keyboard etc)

How to use SpessaSynth in your project

Can't use AudioWorklets because your site doesn't support HTTPS? No problem!

• make the worklet system perform good
• port the worklet system to emscripten (maybe)
• fix modenv
• fix rare clicking in volenv
• fix attenuation modulators

Copyright © 2024 Spessasus. Licensed under the MIT License.