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FluidSynth with Emscripten-specific patch
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FluidSynth with Emscripten-specific patch

This repository is based on FluidSynth repository, and contains some changes to build with Emscripten.

The original README is here:


  1. (Optional) Update emscripten/exports.txt, containing export functions for JS program
    • The script emscripten/make-exports.js will update this automatically, gathering functions from include directory.
  2. Make sure that Emscripten is usable on the current environment
  3. Make build directory
  4. Enter build directory and execute emcmake cmake ..
    • If no options are specified, and cmake is running with emcmake (or emconfigure), the build configurations are initialized for Emscripten-build mode.
  5. Make src/gentables directory in the current build directory
  6. Enter src/gentables directory (build/src/gentables from the root) and execute cmake ../../../src/gentables
    • This calls original CMake to build native make_tables program. Do not use emcmake here.
  7. In build/src/gentables directory, execute make. After successful, execute ./make_tables ../../ (do not forget trailing / character).
    • This is the build step originally written in src/CMakeLists.txt.
  8. Return to build directory (cd ../..) and execute emmake make

After successful build, libfluidsynth-<version>.js will be created at build/src directory.

  • If enable-debug specified on the cmake execution (e.g. emcmake cmake -Denable-debug=on ..), a map file libfluidsynth-<version> is also generated.
    • Currently it seems that it cannot be used.
  • If enable-separate-wasm specified on the cmake execution (e.g. emcmake cmake -Denable-separate-wasm=on ..), libfluidsynth-<version>.wasm and libfluidsynth-<version>.wast are also generated.
    • For AudioWorklet, you cannot use *.wasm file directly.
  • In Emscripten-build mode, standalone application named fluidsynth is not emitted.


Place libfluidsynth-<version>.js file to your space and load libfluidsynth-<version>.js. After load, almost all FluidSynth API functions are accessible via Module object (note that all function names have the prefix _).

To use libfluidsynth-<version>.js in AudioWorklet, load it into AudioWorklet before your worklet JS file. In your worklet JS file, you can access Module object via AudioWorkletGlobalScope.wasmModule.


  • Currently only several APIs are tested. Some APIs such as for drivers may not work.


This program and all source codes, including the original FluidSynth program, its source codes, modifications of FluidSynth source codes for building library with Emscripten, and sources codes used only for building libfluidsynth-<version>.js, are licensed under GNU Lesser General Public License (v2.1) (LGPL v2.1).

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