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!
- 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
?> https://audiomotion.dev/demo/
Install with npm:
$ npm install audiomotion-analyzerUse ES6 import syntax:
import AudioMotionAnalyzer from 'audiomotion-analyzer';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.
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.
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,
start: true,
width: undefined
}
If source is specified, the media element (<audio> or <video>) referenced by the object will be connected to the analyzer.
You can later disconnect it by referring to the audioSource object.
At least one audio source is required for the analyzer to work. You can also connect audio sources with the connectAudio() method.
Object reference: https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaElement
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.
Connect any additional audio sources to this object, so their output is displayed in the graphic analyzer.
Object reference: https://developer.mozilla.org/en-US/docs/Web/API/AnalyserNode
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.setValueAtTime( 440, audioCtx.currentTime ); // play 440Hz tone
oscillator.connect( gainNode );
gainNode.gain.setValueAtTime( .5, audioCtx.currentTime );
gainNode.connect( audioMotion.analyzer );
oscillator.start();Object reference: https://developer.mozilla.org/en-US/docs/Web/API/AudioContext
Object representing the HTML media element connected using the source property in the constructor options,
or, if that was not provided, the first media element connected via the connectAudio() method.
Object reference: https://developer.mozilla.org/en-US/docs/Web/API/MediaElementAudioSourceNode
Canvas element created by audioMotion.
Object reference: https://developer.mozilla.org/en-US/docs/Web/API/HTMLCanvasElement
2D rendering context for drawing in audioMotion's canvas.
Object reference: https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D
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.
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.
Data array updated by the analyzer's getByteFrequencyData() method on every animation frame (ideally 60 times per second).
Array size is defined by analyzer.frequencyBinCount (which should be half the current FFT size), with element values ranging from 0 to 255.
Each array element represents a discrete value in the frequency domain, such that: frequency = index * audioCtx.sampleRate / fftSize.
See also binToFreq() and freqToBin() methods.
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.
See also peakEnergy.
Number of samples used for the FFT performed by the analyzer node. 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.
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.
Current frame rate.
Canvas dimensions used during fullscreen mode. These take the current pixel ratio into account and will change accordingly when low-resolution mode is set.
Currently selected color gradient used for analyzer graphics.
It must be the name of a built-in or registered gradient. Built-in gradients are 'classic', 'prism' and 'rainbow'.
Defaults to 'classic'.
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.
true when the analyzer is being displayed in fullscreen, or false otherwise.
See toggleFullscreen().
true if the analyzer canvas animation is running, or false if it's stopped.
See toggleAnalyzer().
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.
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.
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.
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.
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.
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
fillAlphaandlineWidthproperties).
| 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.
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.
See also spinSpeed.
Defaults to false.
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.
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.
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.
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.
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.
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.
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).
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.
true to display the current frame rate. Defaults to false.
true to activate LED display effect. Only effective for visualization modes 1 to 8 (octave bands). Defaults to false.
true to show amplitude peaks for each frequency. Defaults to true.
true to display the frequency (Hz) scale on the X axis. Defaults to true.
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.
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.
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.
Available since v2.0.0
Returns the version of the audioMotion-analyzer package.
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 = `${ baseSize + instance.energy * 25 * instance.pixelRatio }px Orbitron, sans-serif`;
ctx.fillStyle = '#fff8';
ctx.textAlign = 'center';
ctx.fillText( 'audioMotion', instance.canvas.width - baseSize * 8, baseSize * 2 );
}For more examples, see the fluid demo source code.
If defined, this function will be called whenever the canvas is resized.
Two arguments are passed: a string with the reason why the function was called (see below) and the audioMotion object.
| Reason | Description |
|---|---|
'create' |
canvas created by the audioMotion-analyzer constructor |
'fschange' |
analyzer entered or left fullscreen mode |
'lores' |
low resolution option toggled on or off |
'resize' |
browser window or canvas container element were resized |
'user' |
canvas dimensions changed by user script, via height and width properties, setCanvasSize() or setOptions() methods |
?> As of version 2.5.0, the 'resize' reason is no longer sent on fullscreen changes and
a callback is triggered only when canvas dimensions effectively change from the previous state.
Usage example:
const audioMotion = new AudioMotionAnalyzer(
document.getElementById('container'),
{
source: document.getElementById('audio'),
onCanvasResize: ( reason, instance ) => {
console.log( `[${reason}] canvas size is: ${instance.canvas.width} x ${instance.canvas.height}` );
}
}
);Available since v2.3.0
Returns the frequency (in hertz) represented by a given FFT bin (a dataArray index).
bin must be a number equal or greater than 0 and less than analyzer.frequencyBinCount (the same as dataArray.length).
Connects an HTMLMediaElement (<audio> or <video> HTML element) to the analyzer.
Returns a MediaElementAudioSourceNode which can be used for later disconnection.
For connecting other audio sources, like oscillators and streams, use the audioCtx and analyzer objects.
Available since v2.3.0
Returns the dataArray index which more closely corresponds to a given frequency.
frequency must be a number equal or greater than zero, representing a frequency in hertz.
rounding is an optional string indicating the method to be used for rounding the index value to an integer.
Valid options are 'floor', 'round' (default) and 'ceil'.
See Math static methods.
Please note that the returned value will cap at the highest valid index (analyzer.frequencyBinCount - 1) for any frequency higher
than half the current sampling rate (audioCtx.sampleRate).
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.
Sets the analyzer nominal dimensions in pixels. See height and width properties for details.
Sets the desired frequency range. Values are expressed in Hz (Hertz).
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.
Adjust the analyzer's sensitivity. See maxDecibels and minDecibels properties.
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.
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.
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_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. |
reflexBright feature relies on the filter property of the Canvas API,
which is currently not supported in some browsers (notably, Opera and Safari).
On Firefox, fillAlpha may not work properly for radial visualization, due to this bug.
- Thanks to Yuji Koike for his awesome Soniq Viewer for iOS, which inspired me to create audioMotion
- HTML Canvas Reference @W3Schools
- Web Audio API documentation @MDN
- What does the FFT data in the Web Audio API correspond to?
- Equations for equal-tempered scale frequencies
- Making Audio Reactive Visuals
- The font used in audioMotion's logo is Orbitron by Matt McInerney
- This documentation website is powered by GitHub Pages, docsify and docsify-themeable.
See Changelog.md
If you create something cool with this project, or simply think it's useful, I would like to know! Please drop me an e-mail at [email protected]
If you have a feature request or code suggestion, please see CONTRIBUTING.md
And if you're feeling generous you can buy me a coffee on Ko-fi 😁☕
audioMotion-analyzer copyright (c) 2018-2020 Henrique Avila Vianna
Licensed under the GNU Affero General Public License, version 3 or later.
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