Audiomotion-analyzer NPM

About

version 3.0.0 is in BETA STAGE
:mega: BREAKING CHANGES:
The analyzer object is no longer exposed - use the new connectInput() method for connecting all audio sources and connectOutput() to connect the analyzer output to other nodes;
audioSource property has been renamed to connectedSources and now returns an array of all connected audio sources;
binToFreq() and freqToBin() methods have been removed;
connectAudio() method has been replaced by connectInput(), which now accepts either an HTML media element or any instance of AudioNode;
dataArray property is no longer exposed;
showScale property has been renamed to showScaleX;
version is now a static property and should always be accessed as AudioMotionAnalyzer.version.
NEW FEATURES:
Stereo analyzer option;
Built-in volume control;
New methods:
connectInput()
disconnectInput()
connectOutput()
disconnectOutput()
New properties:
isOctaveBands (read only)
isLedDisplay (read only)
isLumiBars (read only)
stereo
splitGradient
volume

audioMotion-analyzer is a high-resolution real-time audio spectrum analyzer in a vanilla JavaScript module (ES6+) with no dependencies, built upon Web Audio and Canvas APIs. It's highly customizable and optimized for small size and high performance.

I originally wrote this for my audioMotion music player. Check it out too!

Features

High-resolution (retina / HiDPI ready) real-time audio spectrum analyzer with fullscreen support
Logarithmic frequency scale with customizable range
Visualize discrete frequencies with full FFT resolution, or octave bands based on the equal tempered scale
Optional effects: vintage LEDs, luminance bars, customizable reflection, radial visualization
Customizable Web Audio API parameters: FFT size, sensitivity and time-smoothing constant
Comes with 3 predefined color gradients - easily add your own!
No dependencies, less than 20kB minified

Online demos

?> https://audiomotion.dev/demo/

Usage

Using npm and webpack

Install with npm:

$ npm install audiomotion-analyzer

Use ES6 import syntax:

import AudioMotionAnalyzer from 'audiomotion-analyzer';

As a native JavaScript module (ESM)

Simply copy the audioMotion-analyzer.js file from the src folder to your project folder and add the line below to your HTML file:

<body>
  .
  .
	<script src="main.js" type="module"></script>
</body>

And in your main.js file, use:

import AudioMotionAnalyzer from './audiomotion-analyzer.js';

Please note that JavaScript security requirements don't allow loading modules via file:// URLs. You'll need a web server, such as http-server, to test files locally.

Constructor

new AudioMotionAnalyzer( [container], [{options}] )

Creates a new instance of audioMotion-analyzer.

The analyzer canvas will be created and appended to the HTML element referenced by container.

If container is undefined, the canvas will be appended to the document's body.

Usage example:

const audioMotion = new AudioMotionAnalyzer(
	document.getElementById('container'),
	{
		source: document.getElementById('audio')
	}
);

This will insert the analyzer canvas inside the #container element and start the visualization of audio coming from the #audio element.

Options

Available options and default values:

options = { audioCtx: undefined, barSpace: 0.1, bgAlpha: 0.7, fftSize: 8192, fillAlpha: 1, gradient: 'classic', height: undefined, lineWidth: 0, loRes: false, lumiBars: false, maxDecibels: -25, maxFreq: 22000, minDecibels: -85, minFreq: 20, mode: 0, onCanvasDraw: undefined, onCanvasResize: undefined, overlay: false, radial: false, reflexAlpha: 0.15, reflexBright: 1, reflexFit: true, reflexRatio: 0, showBgColor: true, showFPS: false, showLeds: false, showPeaks: true, showScale: true, showScaleY: false, smoothing: 0.5, source: undefined, spinSpeed: 0, splitGradient: true, start: true, stereo: false, volume: 1, width: undefined }

`source` HTMLMediaElement or AudioNode object

If source is specified, connects an HTMLMediaElement object (an <audio> or <video> HTML tag) or, since version 3.0.0, any instance of AudioNode to the analyzer.

At least one audio source is required for the analyzer to work. You can also connect audio sources after instantiation, using the connectInput() method.

`start` boolean

If start: false is specified, the analyzer will be created stopped. You can then start it with the toggleAnalyzer() method.

Defaults to true, so the analyzer will start running right after initialization.

Interface objects (read only)

`audioCtx` AudioContext object

AudioContext used by audioMotion-analyzer. If not provided by the user in the constructor options, it will be created automatically.

Use this object to create additional audio sources to be connected to the analyzer, like oscillator nodes, gain nodes and media streams.

The code fragment below creates an oscillator and a gain node using audioMotion's AudioContext, and then connects them to the analyzer:

const audioMotion = new AudioMotionAnalyzer( document.getElementById('container') ),
      audioCtx    = audioMotion.audioCtx,
      oscillator  = audioCtx.createOscillator(),
      gainNode    = audioCtx.createGain();

oscillator.frequency.value = 440; // set 440Hz frequency
oscillator.connect( gainNode ); // connect oscillator -> gainNode

gainNode.gain.value = .5; // set volume to 50%
audioMotion.connectInput( gainNode ); // connect gainNode -> audioMotion

oscillator.start(); // play tone

`canvas` HTMLCanvasElement object

Canvas element created by audioMotion.

`canvasCtx` CanvasRenderingContext2D object

2D rendering context used for drawing in audioMotion's Canvas.

Properties

`barSpace` number

Available since v2.0.0

Customize the spacing between bars in octave bands modes.

Use a value between 0 and 1 for spacing proportional to the bar width. Values >= 1 will be considered as a literal number of pixels.

For example, barSpace = 0.5 will use half of the bar width for spacing, while barSpace = 2 will set a fixed spacing of 2 pixels, independent of the width of bars. Prefer proportional spacing to obtain consistent results among different resolutions and screen sizes.

barSpace = 0 will effectively show contiguous bars, except when showLeds is true, in which case a minimum spacing is enforced.

Defaults to 0.1.

`bgAlpha` number

Available since v2.2.0

Controls the opacity of the background, when overlay and showBgColor are both set to true.

It must be a number between 0 (completely transparent) and 1 (completely opaque).

Defaults to 0.7.

`connectedSources` array

Available since v3.0.0

An array of AudioNode objects connected via the source constructor option, or by using the connectInput() method.

`energy` number (Read only)

Available since v2.4.0

Returns a number between 0 and 1, representing the instant "energy" of the frequency spectrum. Updated on every animation frame.

The energy value is obtained by a simple average of the amplitudes of currently displayed frequency bands, and roughly represents how loud/busy the spectrum is at a given moment.

You can use this inside your callback function to create additional visual effects. For usage example see the onCanvasDraw documentation.

`fftSize` number

Number of samples used for the FFT performed by the AnalyzerNode. It must be a power of 2 between 32 and 32768, so valid values are: 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, and 32768.

Higher values provide more detail in the frequency domain, but less detail in the time domain (slower response), so you may need to adjust smoothing accordingly.

Defaults to 8192.

`fillAlpha` number

Available since v2.0.0

Opacity of the area fill in Line / Area graph visualization (mode 10).

It must be a number between 0 (completely transparent) and 1 (completely opaque).

Please note that this affects only the area fill. The line (when lineWidth > 0) is always drawn at full opacity.

Defaults to 1.

!> See related known issue

`fps` number (Read only)

Current frame rate.

`fsHeight` number (Read only)

`fsWidth` number (Read only)

Canvas dimensions used during fullscreen mode. These take the current pixel ratio into account and will change accordingly when low-resolution mode is set.

`gradient` string

Currently selected color gradient used for analyzer graphs.

It must be the name of a built-in or registered gradient. Built-in gradients are 'classic', 'prism' and 'rainbow'.

Defaults to 'classic'.

`height` number

`width` number

Nominal dimensions of the analyzer.

If one or both of these are undefined, the analyzer will try to adjust to the container's width and/or height. If the container's width and/or height are 0 (inline elements), a reference size of 640 x 270 pixels will be used to replace the missing dimension(s). This should be considered the minimum dimensions for proper visualization of all available modes with the LED effect on.

You can set both values at once using the setCanvasSize() method.

?> You can read the actual canvas dimensions at any time directly from the canvas object.

`isFullscreen` boolean (Read only)

true when the analyzer is being displayed in fullscreen, or false otherwise.

See toggleFullscreen().

`isLedDisplay` boolean (Read only)

Available since v3.0.0

true when the LED effect is effectively being displayed, i.e., showLeds is set to true and mode is set to one of the octave bands modes.

`isLumiBars` boolean (Read only)

Available since v3.0.0

true when the luminance bars effect is effectively being displayed, i.e., lumiBars is set to true and mode is set to one of the octave bands modes.

`isOctaveBands` boolean (Read only)

Available since v3.0.0

true when mode is set to one of the octave bands modes.

`isOn` boolean (Read only)

true if the analyzer canvas animation is running, or false if it's stopped.

See toggleAnalyzer().

`lineWidth` number

Available since v2.0.0

Line width for the Line / Area graph visualization (mode 10).

For the line to be distinguishable, set also fillAlpha < 1.

Defaults to 0.

`loRes` boolean

true for low resolution mode. Defaults to false.

Low resolution mode halves the effective pixel ratio, resulting in four times less pixels to render. This may improve performance significantly, especially in 4K+ monitors.

?> If you want to allow users to interactively toggle low resolution mode, you may need to set a fixed size for the canvas via CSS, like so:

#container canvas {
    width: 100%;
}

This will prevent the canvas size from changing, when switching the low resolution mode on and off.

`lumiBars` boolean

Available since v1.1.0

This is only effective for visualization modes 1 to 8 (octave bands).

When set to true all analyzer bars will be displayed at full height with varying luminance (opacity, actually) instead.

Defaults to false.

`maxDecibels` number

`minDecibels` number

Highest and lowest decibel values represented in the Y-axis of the analyzer. The loudest volume possible is 0.

maxDecibels defaults to -25 and minDecibels defaults to -85.

You can set both values at once using the setSensitivity() method.

For more info, see AnalyserNode.minDecibels.

`maxFreq` number

`minFreq` number

Highest and lowest frequencies represented in the X-axis of the analyzer. Values in Hertz. maxFreq defaults to 22000 and minFreq defaults to 20.

The minimum allowed value is 1. Trying to set a lower value will throw an ERR_FREQUENCY_TOO_LOW error.

The maximum practical value is half the sampling rate (audioCtx.sampleRate), although this is not enforced by audioMotion-analyzer.

It is preferable to use the setFreqRange() method and set both values at once, to prevent minFreq being higher than the current maxFreq or vice-versa at a given moment.

`mode` number

Current visualization mode.

Discrete frequencies mode provides the highest resolution, allowing you to visualize individual frequencies provided by the FFT;
Octave bands modes display wider vertical bars, each one representing the nth part of an octave, based on a 24-tone equal tempered scale;
Line / Area graph mode uses the discrete frequencies data to draw a filled shape and/or a continuous line (see fillAlpha and lineWidth properties).

mode	description	notes
0	Discrete frequencies
1	1/24th octave bands
2	1/12th octave bands
3	1/8th octave bands
4	1/6th octave bands
5	1/4th octave bands
6	1/3rd octave bands
7	Half octave bands
8	Full octave bands
9	(not valid)	reserved
10	Line / Area graph	added in v1.1.0

Defaults to 0.

`overlay` boolean

Available since v2.2.0

Allows the analyzer to be displayed over other content, by making the canvas background transparent, when set to true.

When showBgColor is also true, bgAlpha controls the background opacity.

Defaults to false.

`peakEnergy` number (Read only)

Available since v2.4.0

Returns a number between 0 and 1, representing the peak energy value of the last 30 frames (approximately 0.5s). Updated on every animation frame.

`pixelRatio` number (Read only)

Current devicePixelRatio. This is usually 1 for standard displays and 2 for retina / Hi-DPI screens.

You can refer to this value to adjust any additional drawings done in the canvas (via callback function).

When loRes is true pixelRatio is halved, i.e. 0.5 for standard displays and 1 for retina / Hi-DPI.

`radial` boolean

Available since v2.4.0

When true, the spectrum analyzer is rendered as a circle, with radial frequency bars spreading from the center of the canvas.

When radial mode is active, lumiBars and showLeds have no effect, and also showPeaks has no effect in Line / Area graph mode.

`reflexAlpha` number

Available since v2.1.0

Reflection opacity (when reflexRatio > 0).

It must be a number between 0 (completely transparent) and 1 (completely opaque).

Defaults to 0.15.

`reflexBright` number

Available since v2.3.0

Reflection brightness (when reflexRatio > 0).

It must be a number. Values below 1 darken the reflection and above 1 make it brighter. A value of 0 will render the reflected image completely black, while a value of 1 will preserve the original brightness.

Defaults to 1.

!> See related known issue

`reflexFit` boolean

Available since v2.1.0

When true, the reflection will be adjusted (stretched or shrinked) to fit the canvas. If set to false the reflected image may be cut at the bottom (when reflexRatio < 0.5) or not fill the entire canvas (when reflexRatio > 0.5).

Defaults to true.

`reflexRatio` number

Available since v2.1.0

Percentage of canvas height used for reflection. It must be a number greater than or equal to 0, and less than 1. Trying to set a value out of this range will throw an ERR_REFLEX_OUT_OF_RANGE error.

For a perfect mirrored effect, set reflexRatio to 0.5 and both reflexAlpha and reflexBright to 1.

This has no effect when lumiBars is true.

Defaults to 0 (no reflection).

`showBgColor` boolean

Determines whether the canvas background should be painted.

If true, the background color defined by the current gradient will be used. Opacity can be adjusted via bgAlpha property, when overlay is true.

If false, the canvas background will be painted black when overlay is false, or transparent when overlay is true.

?> Please note that when overlay is false and showLeds is true, the background color will always be black and setting showBgColor to true will make the "unlit" LEDs visible instead.

Defaults to true.

`showFPS` boolean

true to display the current frame rate. Defaults to false.

`showLeds` boolean

true to activate LED display effect. Only effective for visualization modes 1 to 8 (octave bands). Defaults to false.

`showPeaks` boolean

true to show amplitude peaks for each frequency. Defaults to true.

`showScaleX` boolean

true to display the frequency (Hz) scale on the X axis. Defaults to true.

NOTE: this property was named showScale in versions prior to v3.0.0

`showScaleY` boolean

Available since v2.4.0

true to display the level (dB) scale on the Y axis. Defaults to false.

This option has no effect when radial or lumiBars are set to true.

`smoothing` number

Sets the analyzer's smoothingTimeConstant.

It must be a number between 0 and 1. Lower values make the analyzer respond faster to changes.

Defaults to 0.5.

`spinSpeed` number

Available since v2.4.0

When radial is true, this property defines the analyzer rotation speed, in revolutions per minute.

Positive values will make the analyzer rotate clockwise, while negative values will make it rotate counterclockwise. A value of 0 results in no rotation.

Defaults to 0.

`splitGradient` boolean

Available since v3.0.0

When true, the gradient will be split so both channels have the same colors. If set to false, each channel will get a different part of the gradient.

This option has no effect if stereo is set to false.

Defaults to true.

`stereo` boolean

Available since v3.0.0

When true, the spectrum analyzer will display separate graphs for the left and right audio channels.

`volume` number

Available since v3.0.0

Read or set the output volume.

A value of 0 (zero) will mute the sound output, while a value of 1 will keep the same input volume. Higher values can be used to amplify the input, but it may cause distortion.

Please note that this property does not affect the amplitude of analyzer graphs, but changes to the system's or audio element volume will.

Defaults to 1.

Static properties

`AudioMotionAnalyzer.version` string (Read only)

Available since v3.0.0

Returns the version of the audioMotion-analyzer package.

Since this is a static property, you should always access it as AudioMotionAnalyzer.version - this allows you to check the package version even before instantiating your object.

Callback functions

`onCanvasDraw` function

If defined, this function will be called after rendering each frame.

The audioMotion object will be passed as an argument to the callback function.

Canvas properties fillStyle and strokeStyle will be set to the current gradient when the function is called.

Usage example:

const audioMotion = new AudioMotionAnalyzer(
    document.getElementById('container'),
    {
        source: document.getElementById('audio'),
        onCanvasDraw: drawCallback
    }
);

function drawCallback( instance ) {
	const ctx      = instance.canvasCtx,
    	  baseSize = ( instance.isFullscreen ? 40 : 20 ) * instance.pixelRatio;

    // use the 'energy' value to increase the font size and make the logo pulse to the beat
    ctx.font = `${ baseSize + instance.energy * 25 * instance.pixelRatio }px Orbitron, sans-serif`;

    ctx.fillStyle = '#fff8';
    ctx.textAlign = 'center';
    ctx.fillText( 'audioMotion', instance.canvas.width - baseSize * 8, baseSize * 2 );
}

For more examples, see the fluid demo source code.

`onCanvasResize` function

If defined, this function will be called whenever the canvas is resized.

Two arguments are passed: a string with the reason why the function was called (see below) and the audioMotion object.

Reason	Description
`'create'`	canvas created by the audioMotion-analyzer constructor
`'fschange'`	analyzer entered or left fullscreen mode
`'lores'`	low resolution option toggled on or off
`'resize'`	browser window or canvas container element were resized
`'user'`	canvas dimensions changed by user script, via `height` and `width` properties, `setCanvasSize()` or `setOptions()` methods

?> As of version 2.5.0, the 'resize' reason is no longer sent on fullscreen changes and a callback is triggered only when canvas dimensions effectively change from the previous state.

Usage example:

const audioMotion = new AudioMotionAnalyzer(
    document.getElementById('container'),
    {
        source: document.getElementById('audio'),
        onCanvasResize: ( reason, instance ) => {
            console.log( `[${reason}] canvas size is: ${instance.canvas.width} x ${instance.canvas.height}` );
        }
    }
);

Methods

`connectInput( source )`

Available since v3.0.0

Connects an HTMLMediaElement or an AudioNode (or any of its descendants) to the analyzer.

If source is an HTMLMediaElement, the method returns a MediaElementAudioSourceNode created for that element; if source is an AudioNode instance, it returns the source object itself; if it's neither an ERR_INVALID_AUDIO_SOURCE error is thrown.

`connectOutput( [node] )`

Available since v3.0.0

This method allows connecting audioMotion-analyzer to other audio nodes, e.g. other audio processing modules that use the Web Audio API.

node must be a connected AudioNode; if not specified, the analyzer output is connected to the AudioContext destination (usually the speakers) - this is already done by the construtor, and you should only need to do it again if you disconnect the output.

`disconnectInput( [node] )`

Available since v3.0.0

Disconnects audio source nodes previously connected to the analyzer.

node may be an AudioNode instance or an array of such objects; if not specified, all connected nodes are disconnected.

Please note that if you have connected an <audio> or <video> element, you should disconnect the respective MediaElementAudioSourceNode created for it.

`disconnectOutput( [node] )`

Available since v3.0.0

Disconnects the analyzer output from previously connected audio nodes.

node must be an AudioNode instance; if not specified, the output is disconnected from all nodes (note that this includes the speakers).

`registerGradient( name, options )`

Registers a custom color gradient.

name must be a non-empty string that will be used when setting the gradient property. options must be an object as shown below:

const options = {
    bgColor: '#011a35', // background color (optional) - defaults to '#111'
    dir: 'h',           // add this property to create a horizontal gradient (optional)
    colorStops: [       // list your gradient colors in this array (at least 2 entries are required)
        'red',                      // colors may be defined in any valid CSS format
        { pos: .6, color: '#ff0' }, // use an object to adjust the position (0 to 1) of a color
        'hsl( 120, 100%, 50% )'     // colors may be defined in any valid CSS format
    ]
}

audioMotion.registerGradient( 'my-grad', options );

Additional information about gradient color-stops.

`setCanvasSize( width, height )`

Sets the analyzer nominal dimensions in pixels. See height and width properties for details.

`setFreqRange( minFreq, maxFreq )`

Sets the desired frequency range. Values are expressed in Hz (Hertz).

`setOptions( [options] )`

Shorthand method for setting several options at once.

options should be an object as defined in the class constructor, except for the audioCtx and source properties.

If called with no argument (or options is undefined), resets all configuration options to their default values.

`setSensitivity( minDecibels, maxDecibels )`

Adjust the analyzer's sensitivity. See maxDecibels and minDecibels properties.

`toggleAnalyzer( [boolean] )`

Starts (true) or stops (false) the analyzer animation. If no argument provided, inverts the current status.

Returns the resulting status.

The analyzer is started by default after initialization, unless you specify start: false in the constructor options.

`toggleFullscreen()`

Toggles fullscreen mode on / off.

Please note that fullscreen requests must be triggered by user action, like a key press or mouse click, so you must call this method from within a user-generated event handler.

Also, if you're displaying the analyzer over other content in overlay mode, you'll probably want to handle fullscreen on the container element instead, using your own code. See the overlay demo for an example.

Custom Errors

Available since v2.0.0

audioMotion-analyzer uses a custom error object to throw errors for some critical operations.

The code property is a string label that can be checked to identify the specific error in a reliable way.

code	Error description
ERR_AUDIO_CONTEXT_FAIL	Could not create audio context. The user agent may lack support for the Web Audio API.
ERR_INVALID_AUDIO_CONTEXT	Audio context provided by user is not valid.
ERR_INVALID_AUDIO_SOURCE	Audio source provided in `source` option or `connectInput()` method is not an instance of HTMLMediaElement or AudioNode.
ERR_INVALID_MODE	User tried to set the visualization `mode` to an invalid value.
ERR_FREQUENCY_TOO_LOW	User tried to set the `minFreq` or `maxFreq` properties to a value lower than 1.
ERR_GRADIENT_INVALID_NAME	The `name` parameter for `registerGradient()` must be a non-empty string.
ERR_GRADIENT_NOT_AN_OBJECT	The `options` parameter for `registerGradient()` must be an object.
ERR_GRADIENT_MISSING_COLOR	The `options` parameter for `registerGradient()` must define at least two color-stops.
ERR_REFLEX_OUT_OF_RANGE	Tried to assign a value < 0 or >= 1 to `reflexRatio` property.
ERR_UNKNOWN_GRADIENT	User tried to select a gradient not previously registered.