SpessaSynth is a SoundFont2-based real-time synthesizer and MIDI player written in vanilla JavaScript. It’s a powerful library that allows you to read, write, or play MIDI files and read/write SF2/SF3 files with ease.

npm package now available!

npm install --save spessasynth_lib

Live Demo (no download needed!)

YouTube Video

This repository contains both the library and a complete musical web application. See below:

spessasynth_lib

A flexible, powerful, and feature-packed SoundFont synthesizer library for the WebAudio API. Comes with the ability to edit MIDIs and SoundFonts!

Documentation

Features

Easy Integration

• Modular design: Easy integration into other projects (load what you need)
• Detailed documentation: With examples!
• Easy to Use: basic setup is just two lines of code!
• No dependencies: batteries included!

Powerful SoundFont Synthesizer

• Suitable for both real-time and offline synthesis

• Excellent SoundFont support:

  • Generator Support
  • Modulator Support: First (to my knowledge) JavaScript SoundFont synth with that feature!
  • SoundFont3 Support: Play compressed SoundFonts!
  • Experimental SF2Pack Support: Play soundfonts compressed with BASSMIDI! (Note: only works with vorbis compression)
  • Can load very large SoundFonts: up to 4GB! Note: Only Firefox handles this well; Chromium has a hard-coded memory limit
  • Soundfont manager: Stack multiple soundfonts!

• Reverb and chorus support: customizable!

• Export audio files using OfflineAudioContext

• Custom modulators for additional controllers: Why not?

• Written using AudioWorklets:

  • Runs in a separate thread for maximum performance
  • Supported by all modern browsers

• Unlimited channel count: Your CPU is the limit!

• Excellent MIDI Standards Support:

  • MIDI Controller Support: Default supported controllers here
  • MIDI Tuning Standard Support: more info here
  • Full RPN and limited NRPN support
  • Supports some Roland GS and Yamaha XG system exclusives

• High-performance mode: Play Rush E! note: may kill your browser ;)

Built-in Powerful and Fast Sequencer

• Supports MIDI formats 0, 1, and 2: note: format 2 support is experimental as it's very, very rare
• Multi-Port MIDI support: More than 16 channels!
• Smart preloading: Only preloads the samples used in the MIDI file for smooth playback (down to key and velocity!)
• Lyrics support: Add karaoke to your program!
• Raw lyrics available: Decode in any encoding! (Kanji? No problem!)
• Runs in Audio Thread as well: Never blocks the main thread
• Loop points support: Ensures seamless loops

Read and Write SoundFont and MIDI Files with Ease

Read and write MIDI files

• Smart name detection: Handles incorrectly formatted and non-standard track names
• Raw name available: Decode in any encoding! (Kanji? No problem!)
• Port detection during load time: Manage ports and channels easily!
• Used channels on track: Quickly determine which channels are used
• Key range detection: Detect the key range of the MIDI
• Easy MIDI editing: Use helper functions to modify the song to your needs!
• Loop detection: Automatically detects loops in MIDIs (e.g., from Touhou Project)
• First note detection: Skip unnecessary silence at the start by jumping to the first note!
• Easy saving: Save with just one function!

Read and write RMID files with embedded SF2 soundfonts

• Level 4 compliance: Reads and writes everything!
• Compression and trimming support: Reduce a MIDI file with a 1GB soundfont to as small as 5MB!
• Automatic bank shifting and validation: Every soundfont just works!
• Metadata support: Add title, artist, album name and cover and more! And of course read them too! (In any encoding!)
• Compatible with Falcosoft Midi Player 6!
• Easy saving: As simple as saving a MIDI file!

Read and write SoundFont2 files

• Easy info access: Just an object of strings!
• Smart trimming: Trim the SoundFont to only include samples used in the MIDI (down to key and velocity!)
• sf3 conversion: Compress SoundFont2 files to SoundFont3 with variable quality!
• Easy saving: Also just one function!

Read and write SoundFont3 files

• Same features as SoundFont2 but with now with Ogg Vorbis compression!
• Variable compression quality: You choose between file size and quality!
• Compression preserving: Avoid decompressing and recompressing uncompressed samples for minimal quality loss!

Limitations

• Synth's performance may be suboptimal, especially on mobile devices.

Installation

Npm package

npm install --save spessasynth_lib

Or

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

Tip

Looking for a Node.js version? Try spessasynth_core!

Web App / Local Edition

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

Usage Guide

Features

• Visualization of the played sequence: with cool effects like visual pitch bend and note-on effects!
• Playable keyboard with various sizes: mobile friendly!
• Integrated controller for the synthesizer with numerous options: Edit instruments, controllers, and more!
• Lyrics support: Karaoke!
• Music player mode: with support for album covers in .rmi files!
• Mobile-friendly UI (synthesizer performance not optimized for mobile... don't tell anyone!)
• Multiple language support: English, Polish, Japanese
• Web MIDI API support: Use your physical MIDI devices!
• WebMidiLink support
• Numerous exporting options:
• • Render the MIDI file (modified or unmodified) to .wav
• • Render each channel as a separate .wav file
• • Export the modified MIDI file to .mid
• • Export the trimmed SoundFont to .sf2
• • Or compress it as .sf3!
• • Bundle both as .rmi with metadata such as album cover!
• Comes bundled with a compressed SGM SoundFont to get you started
• No additional dependencies!

Still not convinced? Check out these screenshots:

Installation (Local Edition)

Local edition comes with easier soundfont management than the demo version.

Important

Firefox is recommended for large SoundFonts due to memory constraints. A decent computer is also recommended for handling large SoundFonts.

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

Local Edition requires Node.js

Windows

1. Download the code as a ZIP file 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 start.bat.
4. Enjoy!

Linux

1. Clone the repository:

   git clone https://github.com/spessasus/SpessaSynth
   cd SpessaSynth
   npm start

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

If you would like to help translate SpessaSynth, please read this guide (and thank you!)

If you like this project, consider giving it a star. It really helps out!

TODO

• Improve the performance of the worklet system
• Potentially port the worklet system to Emscripten
• Enhance the built-in chorus and reverb effects (suggestions welcome!)

Special Thanks

• FluidSynth - for the source code that helped implement functionality and fixes
• Polyphone - for the soundfont testing and editing tool
• Meltysynth - for the initial low-pass filter implementation
• RecordingBlogs - for detailed explanations on MIDI messages
• stbvorbis.js - for the Vorbis decoder
• OggVorbisEncoder - for the MIT Vorbis encoder
• Insignify Music - for the great arrangement of Field of Hopes and Dreams
• Falcosoft - for help with the RMIDI format
• And You! - for checking out this project. I hope you like it :)

Major Releases

• 0.0.1 - Initial release
• 1.0.0 - Removed the 2-sample limit
• 2.0.0 - Implemented the worklet system and added support for modulators
• 3.0.0 - Moved to audioWorkletGlobalScope for offline audio rendering

License

Copyright © 2024 Spessasus. Licensed under the MIT License.

Important

Please note that the bundled stbvorbis_sync.js is licensed under the Apache-2.0 license. The license and the file can be found in the externals folder in the spessasynth_lib directory.