WebAudioPlugin Class
Play sounds using Web Audio in the browser. The WebAudioPlugin is currently the default plugin, and will be used anywhere that it is supported. To change plugin priority, check out the Sound API registerPlugins method.
Known Browser and OS issues for Web Audio
Firefox 25For this reason it is recommended to pass another FireFox-supported type (i.e. ogg) as the default extension, until this bug is resolved
Webkit (Chrome and Safari)
iOS 6 limitations
- Sound is initially muted and will only unmute through play being called inside a user initiated event (touch/click). Please read the mobile playback notes in the the Sound class for a full overview of the limitations, and how to get around them.
- A bug exists that will distort un-cached audio when a video element is present in the DOM. You can avoid this bug by ensuring the audio and video audio share the same sample rate.
Constructor
WebAudioPlugin
()
Item Index
Methods
- _addPropsToClasses static
- _compatibilitySetUp static
- _createAudioContext static
- _generateCapabilities static
- _handlePreloadComplete
- _handlePreloadError
- _isFileXHRSupported static
- _unlock
- _updateVolume
- create
- getVolume
- isPreloadComplete
- isPreloadStarted
- isSupported static
- playEmptySound static
- preload
- register
- removeAllSounds
- removeSound
- setMute
- setVolume
Properties
- _audioSources
- _capabilities static
- _panningModel
- _panningModel static
- _scratchBuffer static
- _unlocked
- _volume
- context
- context static
- DEFAULT_SAMPLE_REATE static
- dynamicsCompressorNode
- gainNode
Methods
_addPropsToClasses
()
protected
static
Set up needed properties on supported classes WebAudioSoundInstance and WebAudioLoader.
_compatibilitySetUp
()
private
static
Set up compatibility if only deprecated web audio calls are supported. See http://www.w3.org/TR/webaudio/#DeprecationNotes Needed so we can support new browsers that don't support deprecated calls (Firefox) as well as old browsers that don't support new calls.
_createAudioContext
()
AudioContext | webkitAudioContext
private
static
Create an audio context for the sound.
This method handles both vendor prefixes (specifically webkit support), as well as a case on iOS where audio played with a different sample rate may play garbled when first started. The default sample rate is 44,100, however it can be changed using the WebAudioPlugin/DEFAULT_SAMPLE_RATE:property.
Returns:
_generateCapabilities
()
private
static
Determine the capabilities of the plugin. Used internally. Please see the Sound API capabilities method for an overview of plugin capabilities.
_handlePreloadComplete
-
event
Handles internal preload completion.
Parameters:
-
eventObject
_isFileXHRSupported
()
Boolean
private
static
Determine if XHR is supported, which is necessary for web audio.
Returns:
If XHR is supported.
_unlock
()
private
Try to unlock audio on iOS. This is triggered from either WebAudio plugin setup (which will work if inside of
a mousedown or touchend event stack), or the first document touchend/mousedown event. If it fails (touchend
will fail if the user presses for too long, indicating a scroll event instead of a click event.
Note that earlier versions of iOS supported touchstart for this, but iOS9 removed this functionality. Adding
a touchstart event to support older platforms may preclude a mousedown even from getting fired on iOS9, so we
stick with mousedown and touchend.
_updateVolume
()
protected
Set the gain value for master audio. Should not be called externally.
create
-
src -
startTime -
duration
Create a sound instance. If the sound has not been preloaded, it is internally preloaded here.
Parameters:
Returns:
A sound instance for playback and control.
getVolume
()
Number
Get the master volume of the plugin, which affects all SoundInstances.
Returns:
The volume level, between 0 and 1.
isPreloadComplete
-
src
Checks if preloading has finished for a specific source.
Parameters:
-
srcStringThe sound URI to load.
Returns:
isPreloadStarted
-
src
Checks if preloading has started for a specific source. If the source is found, we can assume it is loading, or has already finished loading.
Parameters:
-
srcStringThe sound URI to check.
Returns:
isSupported
()
Boolean
static
Determine if the plugin can be used in the current browser/OS.
Returns:
If the plugin can be initialized.
playEmptySound
()
static
Plays an empty sound in the web audio context. This is used to enable web audio on iOS devices, as they require the first sound to be played inside of a user initiated event (touch/click). This is called when WebAudioPlugin is initialized (by Sound initializeDefaultPlugins for example).
Example
function handleTouch(event) {
createjs.WebAudioPlugin.playEmptySound();
}preload
-
loader
Internally preload a sound.
Parameters:
-
loaderLoaderThe sound URI to load.
register
-
loadItem
Pre-register a sound for preloading and setup. This is called by Sound.
Note all plugins provide a Loader instance, which PreloadJS
can use to assist with preloading.
Parameters:
-
loadItemStringAn Object containing the source of the audio Note that not every plugin will manage this value.
Returns:
A result object, containing a "tag" for preloading purposes.
removeAllSounds
-
src
Remove all sounds added using WebAudioPlugin/register. Note this does not cancel a preload.
Parameters:
-
srcStringThe sound URI to unload.
removeSound
-
src
Remove a sound added using WebAudioPlugin/register. Note this does not cancel a preload.
Parameters:
-
srcStringThe sound URI to unload.
Properties
_audioSources
Object
protected
Object hash indexed by the source URI of each file to indicate if an audio source has begun loading, is currently loading, or has completed loading. Can be used to store non boolean data after loading is complete (for example arrayBuffers for web audio).
_capabilities
Object
private
static
The capabilities of the plugin. This is generated via the _generateCapabilities method and is used internally.
Default: null
_panningModel
Number / String
protected
Value to set panning model to equal power for WebAudioSoundInstance. Can be "equalpower" or 0 depending on browser implementation.
_panningModel
Number / String
private
static
Value to set panning model to equal power for WebAudioSoundInstance. Can be "equalpower" or 0 depending on browser implementation.
_scratchBuffer
AudioBuffer
private
static
The scratch buffer that will be assigned to the buffer property of a source node on close. Works around an iOS Safari bug: https://github.com/CreateJS/SoundJS/issues/102
Advanced users can set this to an existing source node, but must do so before they call registerPlugins or initializeDefaultPlugins.
_unlocked
Boolean
private
Indicated whether audio on iOS has been unlocked, which requires a touchend/mousedown event that plays an empty sound.
context
AudioContext
The web audio context, which WebAudio uses to play audio. All nodes that interact with the WebAudioPlugin need to be created within this context.
context
AudioContext
static
The web audio context, which WebAudio uses to play audio. All nodes that interact with the WebAudioPlugin need to be created within this context.
Advanced users can set this to an existing context, but must do so before they call registerPlugins or initializeDefaultPlugins.
DEFAULT_SAMPLE_REATE
Number
static
The default sample rate used when checking for iOS compatibility. See _createAudioContext.
Default: 44100
dynamicsCompressorNode
AudioNode
A DynamicsCompressorNode, which is used to improve sound quality and prevent audio distortion.
It is connected to context.destination.
Can be accessed by advanced users through createjs.Sound.activePlugin.dynamicsCompressorNode.
gainNode
AudioGainNode
A GainNode for controlling master volume. It is connected to dynamicsCompressorNode.
Can be accessed by advanced users through createjs.Sound.activePlugin.gainNode.