FaustWasm

The FaustWasm library presents a convenient, high-level API that wraps around Faust compiler. This library's interface is primarily designed for TypeScript usage, although it also provides API descriptions and documentation for pure JavaScript. The WebAssembly version of the Faust Compiler, compatible with both Node.js and web browsers, has been compiled using Emscripten 3.1.31.

The library offers functionality for compiling Faust DSP code into WebAssembly, enabling its utilization as WebAudio nodes within a standard WebAudio node graph. Moreover, it supports offline rendering scenarios. Furthermore, supplementary tools can be employed for generating SVGs from Faust DSP programs.

Synthesizer and effect mono nodes, as well as polyphonic poly nodes can be created. MIDI support is activated as soon as MIDI metadata are used in the DSP code for mono nodes, and always in polyphonic mode.

Sensors (accelerometer and gyroscope) are supported, as well as the Progressive Web Application model.

Usage

Please use a stable version of Node.js 16+ to work with this project.

Use the command line interface

Clone and get into this project:

git clone https://github.com/grame-cncm/faustwasm.git
cd faustwasm

Install development dependencies:

npm install

Possibly:

npm update

Build the files:

npm run build

Versioning

You'll have to raise the package version number in package.json before npm run build to properly work.

Generate WebAssembly version of a Faust DSP

For example:

rm -rf test/out # make sure you are under the faustwasm directory.
node scripts/faust2wasm.js test/mono.dsp test/out

will create a set of files: index.js, dsp-module.wasm, dsp-meta.json, index.html in the out folder. -no-template option will omit index.js and index.html files.

Polyphonic instrument with:

rm -rf test/out # make sure you are under the faustwasm directory.
node scripts/faust2wasm.js test/poly.dsp test/out -poly

will create a set of files: index.js, dsp-module.wasm, dsp-meta.json, index.html (and possibly effect-module.wasm, effect-meta.json) in the out folder.

Creating a Progressive Web Application (PWA) of a Faust DSP

You can create a standalone Progressive Web Application using the command line:

node scripts/faust2wasm.js test/rev.dsp test/rev -pwa

will create a set of files: icon.png, service-worker.js, manifest.json, index.js, dsp-module.wasm, dsp-meta.json, index.html, and the faustwasm, faust-ui folders in the rev folder.

The folder contains the necessary ressources to deploy the Faust application as a PWA on a server, to be installed and used offline. Note that audio files used by the soundfile primitives in the DSP code will have to be mannually added in the folder.

A standalone polyphonic and MIDI standalone Progressive Web Application can be created with:

node scripts/faust2wasm.js test/organ1.dsp test/organ1 -poly -pwa

will create a set of files: icon.png, service-worker.js, manifest.json, index.js, dsp-module.wasm, dsp-meta.json, effect-module.wasm, effect-meta.json, index.html, and the faustwasm, faust-ui folders in the organ1 folder.

Creating a standalone version of a Faust DSP, with audio and MIDI devices selector

You can create a standalone using the command line:

node scripts/faust2wasm.js test/rev.dsp test/rev -standalone

will create a set of files: icon.png, service-worker.js, manifest.json, index.js, dsp-module.wasm, dsp-meta.json, index.html, and the faustwasm, faust-ui folders in the rev folder.

The folder contains the necessary ressources to deploy the Faust application as a PWA on a server, to be installed and used offline. Note that audio files used by the soundfile primitives in the DSP code will have to be mannually added in the folder.

A standalone polyphonic and MIDI standalone Progressive Web Application can be created with:

node scripts/faust2wasm.js test/organ1.dsp test/organ1 -poly -standalone

will create a set of files: icon.png, service-worker.js, manifest.json, index.js, dsp-module.wasm, dsp-meta.json, effect-module.wasm, effect-meta.json, index.html, and the faustwasm, faust-ui folders in the organ1 folder.

Generate SVG Diagrams of a Faust DSP

For example:

rm -rf test/out # make sure you are under the faustwasm directory.
node scripts/faust2svg.js test/mono.dsp test/out

The main diagram should be in test/out/process.svg.

Compile a Faust DSP in a Cmajor file

For example:

rm -rf test/out # make sure you are under the faustwasm directory.
node scripts/faust2cmajor.js test/organ.dsp test/out

The Cmajor file should be in test/out/organ.cmajor.

Generate or process audio files

Options:

• -bs <num> to setup the rendering buffer size in frames (default: 64)
• -bd 16|24|32 to setup the output file bit-depth (default: 16)
• -c <samples> to setup the output file length in frames, when -ct is not used (default: SR*5)
• -in <inputWav.wav> specify an input file to process
• -sr <num> to setup the output file sample rate (default: 44100) See this help:

node scripts/faust2sndfile.js -h

For example:

rm -rf test/out # make sure you are under the faustwasm directory.
mkdir test/out
node scripts/faust2sndfile.js test/p-dj.dsp test/out/p-dj.wav -c 192000 -sr 48000 -bd 24

Now the test/out/p-dj.wav should be generated.

node scripts/faust2sndfile.js test/rev.dsp test/out/p-dj-rev.wav -c 192000 -sr 48000 -bd 24 -in test/out/p-dj.wav

Use the JavaScript Module

npm i -D @grame/faustwasm

In JavaScript:

const FaustWasm = require("@grame/faustwasm");
const path = require("path");
const fs = require("fs");

const {
    instantiateFaustModuleFromFile,
    LibFaust,
    WavEncoder,
    FaustMonoDspGenerator,
    FaustCompiler,
    FaustSvgDiagrams
} = FaustWasm;

(async () => {
    const faustModulePath = path.join(__dirname, "../node_modules/@grame/faustwasm/libfaust-wasm/libfaust-wasm.js");

    // initialize the libfaust wasm
    const faustModule = await instantiateFaustModuleFromFile(faustModulePath);

    // Get the Faust compiler
    const libFaust = new LibFaust(faustModule);
    console.log(libFaust.version());
    const compiler = new FaustCompiler(libFaust);
    const generator = new FaustMonoDspGenerator();
    const sampleRate = 48000;
    const name = "Djembe"
    const argv = ["-I", "libraries/"];
    const code = `
import("stdfaust.lib");
process = ba.pulsen(1, 10000) : pm.djembe(60, 0.3, 0.4, 1);
`;
    // Compile the DSP
    await generator.compile(compiler, name, code, argv.join(" "));
    const processor = await generator.createOfflineProcessor(sampleRate, 1024);

    // Generate SVG diagrams.
    const svgDiagrams = new FaustSvgDiagrams(compiler);
    const svgs = svgDiagrams.from(name, code, argv.join(" "));
    console.log(Object.keys(svgs));

    const out = processor.render(null, 192000);
    const wav = WavEncoder.encode(out, { sampleRate, bitDepth: 24 });

    // The wav file is generated
    fs.writeFileSync(`${__dirname}/out.wav`, new Uint8Array(wav));
})();

Use in a web browser

(async () => {
    const {
        instantiateFaustModuleFromFile,
        LibFaust,
        WavEncoder,
        FaustMonoDspGenerator,
        FaustCompiler,
        FaustSvgDiagrams
    } = await import("../node_modules/@grame/faustwasm/dist/esm/index.js");

    // initialize the libfaust wasm
    const faustModule = await instantiateFaustModuleFromFile("../node_modules/@grame/faustwasm/libfaust-wasm/libfaust-wasm.js");

    // Get the Faust compiler
    const libFaust = new LibFaust(faustModule);
    window.libFaust = libFaust;
    console.log(libFaust.version());
    const compiler = new FaustCompiler(libFaust);
    const generator = new FaustMonoDspGenerator();
    const sampleRate = 48000;
    const name = "Djembe"
    const argv = ["-I", "libraries/"];
    const code = `
import("stdfaust.lib");
process = ba.pulsen(1, 10000) : pm.djembe(60, 0.3, 0.4, 1);
`;
    // Compile the DSP
    await generator.compile(compiler, name, code, argv.join(" "));
    const processor = await generator.createOfflineProcessor(sampleRate, 1024);

    // Generate SVG diagrams.
    const svgDiagrams = new FaustSvgDiagrams(compiler);
    const svgs = svgDiagrams.from(name, code, argv.join(" "));
    console.log(Object.keys(svgs));

    const out = processor.render(null, 192000);
    const wav = WavEncoder.encode(out, { sampleRate, bitDepth: 24 });

    // The wav file is generated
    const blob = new Blob([wav], { type: "audio/wav" });
    const player = document.createElement("audio");
    player.controls = true;
    player.src = URL.createObjectURL(blob);
    document.body.appendChild(player);
    const svg = document.createElement("div");
    svg.innerHTML = svgs["process.svg"];
    document.body.appendChild(svg);
})();

Projects examples

Several examples can be tested by launching a local web server at the faustwasm root level, and going in test/faustlive-wasm and libfaust-in-worklet folders.

The package is used in the following projects:

• faust-web-component, a package providing two web components for embedding interactive Faust snippets in web pages.
• Faust Playground, a Web platform designed to enable children to learn basic audio programming in a simple and graphic way.
• Faust Editor, a simple online editor used to edit, compile and run Faust code from any recent Web Browser with WebAssembly support.
• Faust Web IDE, a more powerfull editor used to edit, compile and run Faust code from any recent Web Browser with WebAssembly support.
• Testing the embedded dynamic Faust compiler page allows to test the compiler, with this HTML source code using this JavaScript code.

Documentation

• Organisation of the API

• Faust Compiler WebAssembly module

• Faust Compiler Javascript Interface

• Faust Wasm Instance

• Faust Audio Nodes Instances and Offline Processor

• High-level API

• How to use with typescript

• Dynamic and Static Instances

• Misc. services

• Important note

Organisation of the API

The API is organised from low to high level as illustrated by the figure below.

Faust Compiler WebAssembly module

The first level is the Faust compiler compiled as a wasm library named libfaust-wasm. It consists in 3 different files:

• libfaust-wasm.wasm : the Faust compiler provided as a WebAssembly module
• libfaust-wasm.js : a Javascript loader of the WebAssembly module
• libfaust-wasm.data : a virtual file system containing the Faust libraries.

The C++ code is compiled with Emscripten and interfaced in LibFaust.ts and types.tsfiles. The loader will take care of providing an instance of the Faust WebAssembly module and of the associated virtual file system (libfaust-wasm.data).

Faust Compiler Javascript Interface

The Faust Compiler Javascript interface is described in FaustCompiler.ts.
It provides classic Faust compilation services, which output is a raw WebAssembly module with an associated JSON description of the module.

Faust Wasm Instance

This level takes a WebAssembly module produced by the Faust compiler or a precompiled module loaded from a file, and builds an instance of this module with the proper Wasm memory layout, ready to run. It is described in FaustDspGenerator.ts, FaustWasmInstantiator.ts, FaustWebAudioDsp.ts and FaustDspInstance.ts files.

Faust Audio Nodes Instances and Offline Processor

This level takes a Faust Wasm instance to build an audio node. AudioWorklet and ScriptProcessor nodes are supported. It is described in FaustAudioWorkletNode.ts and FaustAudioWorkletProcessor.ts files.

Warning: AudioWorklet is a recent technology and may not be supported by all the browsers. Check the compatibility chart.

The audio node API documentation can be accessed here.

Note that ScriptProcessor is marked as deprecated but it's the only audio architecture available in older Safari versions. Both monophonic (generators, effects...) or polyphonic (instruments) nodes can be created. It is described in FaustScriptProcessorNode.ts file.

Created audio nodes have a start and stop methods. When started (which is done by default), they are processing audio buffers. You may have to explicitly stop them to save CPU (and start then again when needed), if for instance several nodes are created at init time before actual use.

An offline processor to render a DSP in a non real-time context and get the computed frames is available. It is described in FaustOfflineProcessor.ts. It will automatically use the start and stop methods internally to activate actual rendering in its plot method.

High-level API

A high-level API is available to compile a DSP program and create the audio node, either monophonic or polyphonic using createNode. Offline processing monophonic or polyphonic nodes can be created using createOfflineProcessor. FFT processing nodes can be created using createFFTNode. It is described in FaustDspGenerator.ts.

How to use with typescript

Simply include the following to get access to types and functions:

///<reference types="@grame/faustwasm"/>

Dynamic and Static Instances

The Faust Wasm and Audio Node levels make it possible to generate instances from Faust dsp code as well as from pre-compiled WebAssembly modules. In the latter case, it is not necessary to include the libfaust-wasm.js library, index.js is sufficient to provide the required services. This allows to generate lighter and faster-loading HTML pages.

Misc. services

• FaustSvgDiagrams.ts: provides facilities to browse Faust generated SVG diagrams
• FaustFFTAudioWorkletProcessor: provides FFT processing

Important note

Html pages embedding the Faust compiler must be served using https, unless using http://localhost.

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