howler.js - 开源音频库工具

Description

howler.js is an audio library for the modern web. It defaults to Web Audio API and falls back to HTML5 Audio . This makes working with audio in JavaScript easy and reliable across all platforms.

Additional information, live demos and a user showcase are available at howlerjs.com .

Features

• Single API for all audio needs
• Defaults to Web Audio API and falls back to HTML5 Audio
• Handles edge cases and bugs across environments
• Supports all codecs for full cross-browser support
• Automatic caching for improved performance
• Control sounds individually, in groups or globally
• Playback of multiple sounds at once
• Easy sound sprite definition and playback
• Full control for fading, rate, seek, volume, etc.
• Easily add 3D spatial sound or stereo panning
• Modular - use what you want and easy to extend
• No outside dependencies, just pure JavaScript
• As light as 7kb gzipped

Browser Compatibility

Tested in the following browsers/versions:

• Google Chrome 7.0+
• Internet Explorer 9.0+
• Firefox 4.0+
• Safari 5.1.4+
• Mobile Safari 6.0+ (after user input)
• Opera 12.0+
• Microsoft Edge

Live Demos

• Audio Player
• Radio
• Spatial Audio
• Audio Sprites

Documentation

Contents

• Quick Start
• Examples
• Core
  • Options
  • Methods
  • Global Options
  • Global Methods
• Plugin: Spatial
  • Options
  • Methods
  • Global Methods
• Mobile Playback
• Dolby Audio Playback
• Format Recommendations
• License

Quick Start

Several options to get up and running:

• Clone the repo: git clone https://github.com/goldfire/howler.js.git
• Install with npm : npm install howler
• Install with Bower : bower install howler
• Hosted CDN: cdnjs jsDelivr

In the browser:

<script src="/path/to/howler.js"></script> <script>     var sound = new Howl({       src: ['sound.webm', 'sound.mp3']     }); </script>

Examples

Most basic, play an MP3:

var sound = new Howl({   src: ['sound.mp3'] });  sound.play();

More playback options:

var sound = new Howl({   src: ['sound.webm', 'sound.mp3', 'sound.wav'],   autoplay: true,   loop: true,   volume: 0.5,   onend: function() {     console.log('Finished!');   } });

Define and play a sound sprite:

var sound = new Howl({   src: ['sounds.webm', 'sounds.mp3'],   sprite: {     blast: [0, 1000],     laser: [2000, 3000],     winner: [4000, 7500]   } });  // Shoot the laser! sound.play('laser');

Listen for events:

var sound = new Howl({   src: ['sound.webm', 'sound.mp3'] });  // Clear listener after first call. sound.once('load', function(){   sound.play(); });  // Fires when the sound finishes playing. sound.on('end', function(){   console.log('Finished!'); });

Control multiple sounds:

var sound = new Howl({   src: ['sound.webm', 'sound.mp3'] });  // Play returns a uniqe Sound ID that can be passed // into any method on Howl to control that specific sound. var id1 = sound.play(); var id2 = sound.play();  // Fade out the first sound and speed up the second. sound.fade(1, 0, 1000, id1); sound.rate(1.5, id2);

More in-depth examples (with accompanying live demos) can be found in theexamples directory.

Core

Options

src Array [] required

The sources to the track(s) to be loaded for the sound (URLs or base64 data URIs). These should be in order of preference, howler.js will automatically load the first one that is compatible with the current browser. If your files have no extensions, you will need to explicitly specify the extension using the ext property.

volume Number 1.0

The volume of the specific track, from 0.0 to 1.0 .

html5 Boolean false

Set to true to force HTML5 Audio. This should be used for large audio files so that you don't have to wait for the full file to be downloaded and decoded before playing.

loop Boolean false

Set to true to automatically loop the sound forever.

preload Boolean true

Automatically begin downloading the audio file when the Howl is defined.

autoplay Boolean false

Set to true to automatically start playback when sound is loaded.

mute Boolean false

Set to true to load the audio muted.

sprite Object {}

Define a sound sprite for the sound. The offset and duration are defined in milliseconds. A third (optional) parameter is available to set a sprite as looping. An easy way to generate compatible sound sprites is withaudiosprite.

{   key: [offset, duration, (loop)] }

rate Number 1.0

The rate of playback. 0.5 to 4.0, with 1.0 being normal speed.

pool Number 5

The size of the inactive sounds pool. Once sounds are stopped or finish playing, they are marked as ended and ready for cleanup. We keep a pool of these to recycle for improved performance. Generally this doesn't need to be changed. It is important to keep in mind that when a sound is paused, it won't be removed from the pool and will still be considered active so that it can be resumed later.

format Array []

howler.js automatically detects your file format from the extension, but you may also specify a format in situations where extraction won't work (such as with a SoundCloud stream).

onload Function

Fires when the sound is loaded.

onloaderror Function

Fires when the sound is unable to load. The first parameter is the ID of the sound (if it exists) and the second is the error message/code.

onplay Function

Fires when the sound begins playing. The first parameter is the ID of the sound.

onend Function

Fires when the sound finishes playing (if it is looping, it'll fire at the end of each loop). The first parameter is the ID of the sound.

onpause Function

Fires when the sound has been paused. The first parameter is the ID of the sound.

onstop Function

Fires when the sound has been stopped. The first parameter is the ID of the sound.

onmute Function

Fires when the sound has been muted/unmuted. The first parameter is the ID of the sound.

onvolume Function

Fires when the sound's volume has changed. The first parameter is the ID of the sound.

onrate Function

Fires when the sound's playback rate has changed. The first parameter is the ID of the sound.

onseek Function

Fires when the sound has been seeked. The first parameter is the ID of the sound.

onfade Function

Fires when the current sound finishes fading in/out. The first parameter is the ID of the sound.

Methods

play([sprite/id])

Begins playback of a sound. Returns the sound id to be used with other methods. Only method that can't be chained.

• sprite/id : String/Number optional Takes one parameter that can either be a sprite or sound ID. If a sprite is passed, a new sound will play based on the sprite's definition. If a sound ID is passed, the previously played sound will be played (for example, after pausing it). However, if an ID of a sound that has been drained from the pool is passed, nothing will play.

pause([id])

Pauses playback of sound or group, saving the seek of playback.

• id : Number optional The sound ID. If none is passed, all sounds in group are paused.

stop([id])

Stops playback of sound, resetting seek to 0 .

• id : Number optional The sound ID. If none is passed, all sounds in group are stopped.

mute([muted], [id])

Mutes the sound, but doesn't pause the playback.

• muted : Boolean optional True to mute and false to unmute.
• id : Number optional The sound ID. If none is passed, all sounds in group are stopped.

volume([volume], [id])

Get/set volume of this sound or the group. This method optionally takes 0, 1 or 2 arguments.

• volume : Number optional Volume from 0.0 to 1.0 .
• id : Number optional The sound ID. If none is passed, all sounds in group have volume altered relative to their own volume.

fade(from, to, duration, [id])

Fade a currently playing sound between two volumes. Fires the fade event when complete.

• from : Number Volume to fade from ( 0.0 to 1.0 ).
• to : Number Volume to fade to ( 0.0 to 1.0 ).
• duration : Number Time in milliseconds to fade.
• id : Number optional The sound ID. If none is passed, all sounds in group will fade.

rate([rate], [id])

Get/set the rate of playback for a sound. This method optionally takes 0, 1 or 2 arguments.

• rate : Number optional The rate of playback. 0.5 to 4.0, with 1.0 being normal speed.
• id : Number optional The sound ID. If none is passed, playback rate of all sounds in group will change.

seek([seek], [id])

Get/set the position of playback for a sound. This method optionally takes 0, 1 or 2 arguments.

• seek : Number optional The position to move current playback to (in seconds).
• id : Number optional The sound ID. If none is passed, the first sound will seek.

loop([loop], [id])

Get/set whether to loop the sound or group. This method can optionally take 0, 1 or 2 arguments.

• loop : Boolean optional To loop or not to loop, that is the question.
• id : Number optional The sound ID. If none is passed, all sounds in group will have their loop property updated.

state()

Check the load status of the Howl , returns a unloaded , loading or loaded .

playing(id)

Check if a sound is currently playing or not, returns a Boolean . If no sound ID is passed, check if any sound in the Howl group is playing.

• id : Number The sound ID to check.

duration([id])

Get the duration of the audio source. Will return 0 until after the load event fires.

• id : Number optional The sound ID to check. Passing an ID will return the duration of the sprite being played on this instance; otherwise, the full source duration is returned.

on(event, function, [id])

Listen for events. Multiple events can be added by calling this multiple times.

• event : String Name of event to fire/set ( load , loaderror , play , end , pause , stop , mute , volume , rate , seek , fade ).
• function : Function Define function to fire on event.
• id : Number optional Only listen to events for this sound id.

once(event, function, [id])

Same as on , but it removes itself after the callback is fired.

• event : String Name of event to fire/set ( load , loaderror , play , end , pause , stop , mute , volume , rate , seek , fade ).
• function : Function Define function to fire on event.
• id : Number optional Only listen to events for this sound id.

off(event, [function], [id])

Remove event listener that you've set. Call without parameters to remove all events.

• event : String Name of event ( load , loaderror , play , end , pause , stop , mute , volume , rate , seek , fade ).
• function : Function optional The listener to remove. Omit this to remove all events of type.
• id : Number optional Only remove events for this sound id.

load()

This is called by default, but if you set preload to false, you must call load before you can play any sounds.

unload()

Unload and destroy a Howl object. This will immediately stop all sounds attached to this sound and remove it from the cache.

Global Options

usingWebAudio Boolean

true if the Web Audio API is available.

noAudio Boolean

true if any audio is available.

mobileAutoEnable Boolean true

Automatically attempts to enable audio on mobile (iOS, Android, etc) devices.

autoSuspend Boolean true

Automatically suspends the Web Audio AudioContext after 30 seconds of inactivity to decrease processing and energy usage. Automatically resumes upon new playback. Set this property to false to disable this behavior.

ctx Boolean Web Audio Only

Exposes the AudioContext with Web Audio API.

masterGain Boolean Web Audio Only

Exposes the master GainNode with Web Audio API. This can be useful for writing plugins or advanced usage.

Global Methods

The following methods are used to modify all sounds globally, and are called from the Howler object.

mute(muted)

Mute or unmute all sounds.

• muted : Boolean True to mute and false to unmute.

volume([volume])

Get/set the global volume for all sounds, relative to their own volume.

• volume : Number optional Volume from 0.0 to 1.0 .

codecs(ext)

Check supported audio codecs. Returns true if the codec is supported in the current browser.

• ext : String File extension. One of: "mp3", "mpeg", opus", "ogg", "oga", "wav", "aac", "caf", m4a", "mp4", "weba", "webm", "dolby".

unload()

Unload and destroy all currently loaded Howl objects. This will immediately stop all sounds and remove them from cache.

Plugin: Spatial

Options

orientation Array [1, 0, 0]

Sets the direction the audio source is pointing in the 3D cartesian coordinate space. Depending on how direction the sound is, based on the cone attributes, a sound pointing away from the listener can be quiet or silent.

stereo Number null

Sets the stereo panning value of the audio source for this sound or group. This makes it easy to setup left/right panning with a value of -1.0 being far left and a value of 1.0 being far right.

pos Array null

Sets the 3D spatial position of the audio source for this sound or group. Setting any value higher than 1.0 will begin to decrease the volume of the sound as it moves further away.

pannerAttr Object

Sets the panner node's attributes for a sound or group of sounds. See the pannerAttr method for all available options.

onstereo Function

Fires when the current sound has the stereo panning changed. The first parameter is the ID of the sound.

onpos Function

Fires when the current sound has the listener position changed. The first parameter is the ID of the sound.

onorientation Function

Fires when the current sound has the direction of the listener changed. The first parameter is the ID of the sound.

Methods

stereo(pan, [id])

Get/set the stereo panning of the audio source for this sound or all in the group.

• pan : Number A value of -1.0 is all the way left and 1.0 is all the way right.
• id : Number optional The sound ID. If none is passed, all in group will be updated.

pos(x, y, z, [id])

Get/set the 3D spatial position of the audio source for this sound or group. Setting any value higher than 1.0 will begin to decrease the volume of the sound as it moves further away.

• x : Number The x-position of the audio from -1000.0 to 1000.0 .
• y : Number The y-position of the audio from -1000.0 to 1000.0 .
• z : Number The z-position of the audio from -1000.0 to 1000.0 .
• id : Number optional The sound ID. If none is passed, all in group will be updated.

orientation(x, y, z, [id])

Get/set the direction the audio source is pointing in the 3D cartesian coordinate space. Depending on the direction of the sound, based on the cone attributes, a sound pointing away from the listener can be quiet or silent.

• x : Number The x-orientation of the source.
• y : Number The y-orientation of the source.
• z : Number The z-orientation of the source.
• id : Number optional The sound ID. If none is passed, all in group will be updated.

pannerAttr(o, [id])

Get/set the panner node's attributes for a sound or group of sounds. This method can optionall take 0, 1 or 2 arguments.

• o : Object All values to update.
  • coneInnerAngle 360 There will be no volume reduction inside this angle.
  • coneOuterAngle 360 The volume will be reduced to a constant value of coneOuterGain outside this angle.
  • coneOuterGain 0 The amount of volume reduction outside of coneOuterAngle .
  • distanceModel inverse Determines algorithm to use to reduce volume as audio moves away from listener. Can be linear , inverse or `exponential.
  • maxDistance 10000 Volume won't reduce between source/listener beyond this distance.
  • panningModel HRTF Determines which spatialization algorithm is used to position audio. Can be HRTF or equalpower .
  • refDistance 1 A reference distance for reducing volume as the source moves away from the listener.
  • rolloffFactor 1 How quickly the volume reduces as source moves from listener.
• id : Number optional The sound ID. If none is passed, all in group will be updated.

Global Methods

stereo(pan)

Helper method to update the stereo panning position of all current Howls . Future Howls will not use this value unless explicitely set.

• pan : Number A value of -1.0 is all the way left and 1.0 is all the way right.

pos(x, y, z)

Get/set the position of the listener in 3D cartesian space. Sounds using 3D position will be relative to the listener's position.

• x : Number The x-position of the listener.
• y : Number The y-position of the listener.
• z : Number The z-position of the listener.

orientation(x, y, z, xUp, yUp, zUp)

Get/set the direction the listener is pointing in the 3D cartesian space. A front and up vector must be provided. The front is the direction the face of the listener is pointing, and up is the direction the top of the listener is pointing. Thus, these values are expected to be at right angles from each other.

• x : Number The x-orientation of listener.
• y : Number The y-orientation of listener.
• z : Number The z-orientation of listener.
• xUp : Number The x-orientation of the top of the listener.
• yUp : Number The y-orientation of the top of the listener.
• zUp : Number The z-orientation of the top of the listener.

Mobile Playback

By default, audio on iOS, Android, etc is locked until a sound is played within a user interaction, and then it plays normally the rest of the page session ( Apple documentation ). The default behavior of howler.js is to attempt to silently unlock audio playback by playing an empty buffer on the first touchend event. This behavior can be disabled by calling:

Howler.mobileAutoEnable = false;

Dolby Audio Playback

Full support for playback of the Dolby Audio format (currently support in Edge and Safari) is included. However, you must specify that the file you are loading is dolby since it is in a mp4 container.

var dolbySound = new Howl({   src: ['sound.mp4', 'sound.webm', 'sound.mp3'],   format: ['dolby', 'webm', 'mp3'] });

Format Recommendations

Howler.js supports a wide array of audio codecs that have varying browser support ("mp3", "opus", "ogg", "wav", "aac", "m4a", "mp4", "webm", ...), but if you want full browser coverage you still need to use at least two of them. If your goal is to have the best balance of small filesize and high quality, based on extensive production testing, your best bet is to default to webm and fallback to mp3 . webm has nearly full browser coverage with a great combination of compression and quality. You'll need the mp3 fallback for Internet Explorer.

It is important to remember that howler.js selects the first compatible sound from your array of sources. So if you want webm to be used before mp3 , you need to put the sources in that order.

If you want your webm files to be seekable in Firefox, be sure to encode them with the cues element. One way to do this is by using the dash flag in ffmpeg :

ffmpeg -i sound1.wav -dash 1 sound1.webm

License

Copyright (c) 2013-2016 James Simpson and GoldFire Studios, Inc.

Released under theMIT License.