Audio-effects

A javascript library to create audio effects using the web-audio-api. This library contains the following effects:

• Volume
• Distortion
• Delay
• Flanger
• Reverb
• Tremolo

I will try to add more effects in the future.

Install

npm install --save audio-effects

API

Audio context

To start, we need an audio-context, the audio-effect library has a useful helper function to check if the current browser supports the web-audio-api.

import {HasAudioContext} from 'audio-effects';

let audioContext = null;

if (HasAudioContext) {
    audioContext = new AudioContext();
}

Input

An input node manages the audio input. You can either supply an audio stream.

import {Input} from 'audio-effects';

const stream = createAnAudioStream(); // Some audio stream
const input = new Input(audioContext);
      input.input = stream;

Or use the getUserMedia method to access the devices microphone.

import {Input} from 'audio-effects';

const input = new Input(audioContext);
      input.getUserMedia();

Output

This is the audio node which should be at the end of the chain, this connects our audio to the device's speakers.

import {Output} from 'audio-effects';

const output = new Output(audioContext);

Volume

Control the volume of your audio or mute it.

import {Volume} from 'audio-effects';

const volume = new Volume(audioContext);
      volume.level = 0.5; // Change the volume to 50%
      volume.mute = true; // Mute the volume

Distortion

Add a distortion effect

import {Distortion} from 'audio-effects';

const distortion = new Distortion(audioContext);
      distortion.intensity = 200; // Set the intensity to 200
      distortion.gain = 100; // Set the gain to 100
      distortion.lowPassFilter = true; // Enable the lowpass filter

Delay

Add a delay effect

import {Delay} from 'audio-effects';

const delay = new Delay(audioContext);
      delay.wet = 1; // Set the wetness to 100%
      delay.speed = 1; // Set the speed to 1 second
      delay.duration = 0.4; // Set the delay duration to 40%

Flanger

Add a Flanger effect

import {Flanger} from 'audio-effects';

const flanger = new Flanger(audioContext);
      flanger.delay = 0.005; // Set the delay to 0.005 seconds
      flanger.depth = 0.002; // Set the depth to 0.002
      flanger.feedback = 0.5; // Set the feedback to 50%
      flanger.speed = 0.25; // Set the speed to 0.25 Hz

Reverb

Add a Reverb effect

import {Reverb} from 'audio-effects';

const reverb = new Reverb(audioContext)
      reverb.wet = 0.5; // Set the wetness to 50%
      reverb.level = 1; // Set the level to 100%

By default the reverb effect will use the hall-reverb impulse response file from the awesome web-audio-playground by Chris Wilson.

if you want to use your own impulse response file you can configure it in 2 ways:

const irf = fetch('path/to/impulse-response-file', {
          method: 'get'
      }).then(response => {
          return response.arrayBuffer();
      });

      // Option 1: pass it as a parameter when creating the reverb effect
      irf.then(buffer => {
         const reverb = new Reverb(audioContext, buffer);
      });

      // Option 2: set the buffer after creating the reverb effect
      const reverb = new Reverb(audioContext);

      irf.then(buffer => {
         reverb.buffer = buffer;
      });

Tremolo

Add a Tremolo effect

import {Tremolo} from 'audio-effects';

const tremolo = new Tremolo(audioContext);
      tremolo.delay = 1; // Set the speed to 1Hz

Chaining

Like regular audio nodes, these nodes need to be chained together to connect the input to effects and the output. The api is the same as with normal audio nodes.

input.connect(output);

Unlike their native counterparts, audio-effects' audio nodes can also be chained together.

input.connect(volume).connect(distortion).connect(output);

Helper functions

The audio-effects library has some built-in helper functions.

import {HasAudioContext, HasGetUserMedia} from 'audio-effects';

if (HasAudioContext) {
    // The current browser supports the web-audio-api.
}

if (HasGetUserMedia {
    // The current browser supports getUserMedia.
}

Create your own effects

It is possible to create your own effects.

import {SingleAudioNode} from 'audio-effects';

class CustomEffect extends SingleAudioNode {
    constructor(audioContext) {
        super(audioContext);

        // All audio nodes needed for the effect should be kept in the nodes object.
        this.nodes = {
            node1: audioContext.createGain(),
            node2: audioContext.createGain(),
            node3: audioContext.createGain(),
        };

        // Connect all nodes
        // [node 1]-->>--[node 2]-->>--[node 3]
        this.nodes.node1.connect(this.nodes.node2);
        this.nodes.node2.connect(this.nodes.node3);

        // Set the  input-node, this is the first node in the effect's chain.
        this._node = this.nodes.node1;

        // Set the output-node, this is the last node in the effect's chain.
        this._outputNode = this.nodes.node3;
    }

    // Create getters and setters for the parameters you want to be customizable.
    get gain() {
        return this.nodes.node1.gain.value;
    }

    set gain(gain) {
        this.nodes.node1.gain.value = parseFloat(gain);
    }

    ...
}

Todo

• Write tests!
• Add tuner
• Add chorus
• Add auto-wah
• ...

License

The MIT License (MIT)

Copyright © 2016 Sam Bellen

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.