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jfxr

This library is the core of the jfxr sound effects generator. jfxr generates sounds from a small JSON object containing parameters like pitch, duration and effects.

The library was developed only for running in the browser, but it can be made to work in a Node.js environment as well. If you need that, please file an issue.

Installation

The module is built using UMD, so it should work with AMD, CommonJS, or as a browser global. Use one of these approaches:

  • To use it in the browser without any module system, you can use the minified bundle dist/jfxr.min.js, and include it via a <script> tag:

      <script src="jfxr.js"></script>

    This will expose the API on the global jfxr object.

  • If you want to use it as a proper module:

      npm install --save jfxr

    Then import it and use it using one of:

      var jfxr = require('jfxr');  // Node.js syntax (CommonJS)
  import jfxr from 'jfxr';     // ES2015 module syntax

Example

This shows how you might run the synthesizer, and then play the resulting sound effect using the AudioContext API.

var AudioContext = new AudioContext();

var synth = new jfxr.Synth(mySound);

synth.run(function(clip) {
  var buffer = context.createBuffer(1, clip.array.length, clip.sampleRate);
  buffer.getChannelData(0).set(clip.toFloat32Array());
  context.resume().then(function() {
    var source = context.createBufferSource();
    source.buffer = buffer;
    source.start(0);
  });
});

API

Synth

The Synth class is what produces the sound. Its interface is very simple:

  • new Synth(str) creates a new synth object which can render the sound described by the string str. This must be a valid JSON string as saved from the jfxr app (the contents of a .jfxr file).

  • synth.run(callback) starts synthesis asynchronously. When complete, the callback is invoked with a single parameter, clip, which is a Clip object.

  • synth.cancel() cancels any in-progress synthesis.

Clip

The Clip class represents a rendered sound effect. It's just a wrapper around an array of samples.

  • clip.getNumSamples() returns the number of audio samples in the clip.

  • clip.getSampleRate() returns the sample rate in Hertz, typically 44100.

  • clip.toFloat32Array() returns a Float32Array containing the generated samples (mono). Usually the values will be between -1 and 1.

  • clip.toWavBytes() returns a Uint8Array containing the raw bytes of a WAV file, encoded in 16-bits PCM.