window.runtime property | window.runtime.flash.media.Microphone |
Inheritance | Microphone EventDispatcher Object |
Runtime Versions: | AIR 1.0, |
To get a reference to a Microphone instance, use the Microphone.getMicrophone()
method
or the Microphone.getEnhancedMicrophone()
method. An enhanced microphone instance can
perform acoustic echo cancellation. Use acoustic echo cancellation to create real-time audio/video applications
that don't require headsets.
Create a real-time chat application
To create a real-time chat application, capture audio and send it to Flash Media Server.
Use the NetConnection and NetStream classes to send the audio stream to Flash Media Server.
Flash Media Server can broadcast the audio to other clients.
To create a chat application that doesn't require headsets, use acoustic echo
cancellation. Acoustic echo cancellation prevents the feedback loop that occurs when audio enters a microphone,
travels out the speakers, and enters the microphone again. To use acoustic echo cancellation, call
the Microphone.getEnhancedMicrophone()
method to get a reference to a Microphone instance.
Set Microphone.enhancedOptions
to an instance of the MicrophoneEnhancedOptions
class to
configure settings.
Play microphone audio locally
Call the Microphone setLoopback()
method to route the microphone audio directly to
the local computer or device audio output. Uncontrolled audio feedback is an inherent danger and is likely
to occur whenever the audio output can be picked up by the microphone input. The
setUseEchoSuppression()
method can reduce, but not eliminate, the risk of feedback
amplification.
Capture microphone audio for local recording or processing
To capture microphone audio, listen for the sampleData
events dispatched by a
Microphone instance. The SampleDataEvent object dispatched for this event contains the audio data.
For information about capturing video, see the Camera class.
Runtime microphone support
The Microphone class is not supported in Flash Player running in a mobile browser.
You can test for support at run time using the Microphone.isSupported
property.
Note that for AIR for TV devices, Microphone.isSupported
is true
but
Microphone.getMicrophone()
always returns null
.
Privacy controls
Flash Player displays a Privacy dialog box that lets the user choose whether to allow or deny access to the microphone. Your application window size must be at least 215 x 138 pixels, the minimum size required to display the dialog box, or access is denied automatically.
Content running in the AIR application sandbox does not need permission to access the microphone and no dialog is displayed. AIR content running outside the application sandbox does require permission and the Privacy dialog is displayed.
See also
Property | Defined By | ||
---|---|---|---|
activityLevel : Number [read-only]
The amount of sound the microphone is detecting. | Microphone | ||
codec : String | Microphone | ||
constructor : Object
A reference to the class object or constructor function for a given object instance. | Object | ||
enableVAD : Boolean
Enable Speex voice activity detection. | Microphone | ||
encodeQuality : int
The encoded speech quality when using the Speex codec. | Microphone | ||
enhancedOptions : MicrophoneEnhancedOptions
Controls enhanced microphone options. | Microphone | ||
framesPerPacket : int
Number of Speex speech frames transmitted in a packet (message). | Microphone | ||
gain : Number
The amount by which the microphone boosts the signal. | Microphone | ||
index : int [read-only]
The index of the microphone, as reflected in the array returned by
Microphone.names. | Microphone | ||
isSupported : Boolean [static] [read-only]
The isSupported property is set to true if the
Microphone class is supported on the current platform, otherwise it is
set to false. | Microphone | ||
muted : Boolean [read-only]
Specifies whether the user has denied access to the microphone (true)
or allowed access (false). | Microphone | ||
name : String [read-only]
The name of the current sound capture device, as returned by the sound capture hardware. | Microphone | ||
names : Array [static] [read-only]
An array of strings containing the names of all available sound capture devices. | Microphone | ||
noiseSuppressionLevel : int
Maximum attenuation of the noise in dB (negative number) used for Speex encoder. | Microphone | ||
prototype : Object [static]
A reference to the prototype object of a class or function object. | Object | ||
rate : int
The rate at which the microphone is capturing sound, in kHz. | Microphone | ||
silenceLevel : Number [read-only]
The amount of sound required to activate the microphone and dispatch
the activity event. | Microphone | ||
silenceTimeout : int [read-only]
The number of milliseconds between the time the microphone stops
detecting sound and the time the activity event is dispatched. | Microphone | ||
soundTransform : flash.media:SoundTransform
Controls the sound of this microphone object when it is in loopback mode. | Microphone | ||
useEchoSuppression : Boolean [read-only]
Set to true if echo suppression is enabled; false otherwise. | Microphone |
Method | Defined By | ||
---|---|---|---|
addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void
Registers an event listener object with an EventDispatcher object so that the listener
receives notification of an event. | EventDispatcher | ||
dispatchEvent(event:Event):Boolean
Dispatches an event into the event flow. | EventDispatcher | ||
getEnhancedMicrophone(index:int = -1):Microphone [static]
Returns a reference to an enhanced Microphone object that can
perform acoustic echo cancellation. | Microphone | ||
getMicrophone(index:int = -1):Microphone [static]
Returns a reference to a Microphone object for capturing audio. | Microphone | ||
hasEventListener(type:String):Boolean
Checks whether the EventDispatcher object has any listeners registered for a specific type
of event. | EventDispatcher | ||
hasOwnProperty(name:String):Boolean
Indicates whether an object has a specified property defined. | Object | ||
isPrototypeOf(theClass:Object):Boolean
Indicates whether an instance of the Object class is in the prototype chain of the object specified
as the parameter. | Object | ||
propertyIsEnumerable(name:String):Boolean
Indicates whether the specified property exists and is enumerable. | Object | ||
removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void
Removes a listener from the EventDispatcher object. | EventDispatcher | ||
setLoopBack(state:Boolean = true):void
Routes audio captured by a microphone to the local speakers. | Microphone | ||
setPropertyIsEnumerable(name:String, isEnum:Boolean = true):void
Sets the availability of a dynamic property for loop operations. | Object | ||
setSilenceLevel(silenceLevel:Number, timeout:int = -1):void
Sets the minimum input level that should be considered sound and (optionally) the amount
of silent time signifying that silence has actually begun. | Microphone | ||
setUseEchoSuppression(useEchoSuppression:Boolean):void
Specifies whether to use the echo suppression feature of the audio codec. | Microphone | ||
toLocaleString():String
Returns the string representation of this object, formatted according to locale-specific conventions. | Object | ||
toString():String
Returns the string representation of the specified object. | Object | ||
valueOf():Object
Returns the primitive value of the specified object. | Object | ||
willTrigger(type:String):Boolean
Checks whether an event listener is registered with this EventDispatcher object or any of
its ancestors for the specified event type. | EventDispatcher |
Event | Summary | Defined By | ||
---|---|---|---|---|
[broadcast event] Dispatched when the Flash Player or AIR application gains operating system focus and becomes active. | EventDispatcher | |||
Dispatched when a microphone starts or stops recording due to detected silence. | Microphone | |||
[broadcast event] Dispatched when the Flash Player or AIR application operating loses system focus and is becoming inactive. | EventDispatcher | |||
Dispatched when the microphone has sound data in the buffer. | Microphone | |||
Dispatched when a microphone reports its status. | Microphone |
activityLevel | property |
activityLevel:Number
[read-only] Runtime Versions: | AIR 1.0, |
The amount of sound the microphone is detecting. Values range from
0 (no sound is detected) to 100 (very loud sound is detected). The value of this property can
help you determine a good value to pass to the Microphone.setSilenceLevel()
method.
If the microphone muted
property is true
, the value of this property is always -1.
See also
codec | property |
enableVAD | property |
enableVAD:Boolean
Runtime Versions: | 2 |
Enable Speex voice activity detection.
encodeQuality | property |
encodeQuality:int
Runtime Versions: | 1.5 |
The encoded speech quality when using the Speex codec. Possible values are from 0 to 10. The default value is 6. Higher numbers represent higher quality but require more bandwidth, as shown in the following table. The bit rate values that are listed represent net bit rates and do not include packetization overhead.
Quality value | Required bit rate (kilobits per second) |
---|---|
0 | 3.95 |
1 | 5.75 |
2 | 7.75 |
3 | 9.80 |
4 | 12.8 |
5 | 16.8 |
6 | 20.6 |
7 | 23.8 |
8 | 27.8 |
9 | 34.2 |
10 | 42.2 |
See also
enhancedOptions | property |
enhancedOptions:MicrophoneEnhancedOptions
Runtime Versions: | 2.7 |
Controls enhanced microphone options. For more information, see
MicrophoneEnhancedOptions
class. This property is ignored for non-enhanced Microphone instances.
See also
framesPerPacket | property |
framesPerPacket:int
Runtime Versions: | 1.5 |
Number of Speex speech frames transmitted in a packet (message). Each frame is 20 ms long. The default value is two frames per packet.
The more Speex frames in a message, the lower the bandwidth required but the longer the delay in sending the message. Fewer Speex frames increases bandwidth required but reduces delay.
gain | property |
gain:Number
Runtime Versions: | AIR 1.0, |
The amount by which the microphone boosts the signal. Valid values are 0 to 100. The default value is 50.
See also
index | property |
index:int
[read-only] Runtime Versions: | AIR 1.0, |
The index of the microphone, as reflected in the array returned by
Microphone.names
.
See also
isSupported | property |
isSupported:Boolean
[read-only] Runtime Versions: | 2 |
The isSupported
property is set to true
if the
Microphone class is supported on the current platform, otherwise it is
set to false
.
muted | property |
muted:Boolean
[read-only] Runtime Versions: | AIR 1.0, |
Specifies whether the user has denied access to the microphone (true
)
or allowed access (false
). When this value changes,
a status
event is dispatched.
For more information, see Microphone.getMicrophone()
.
See also
name | property |
name:String
[read-only] Runtime Versions: | AIR 1.0, |
The name of the current sound capture device, as returned by the sound capture hardware.
See also
names | property |
names:Array
[read-only] Runtime Versions: | AIR 1.0, |
An array of strings containing the names of all available sound capture devices.
The names are returned without
having to display the Flash Player Privacy Settings panel to the user. This array
provides the zero-based index of each sound capture device and the
number of sound capture devices on the system, through the Microphone.names.length
property.
For more information, see the Array class entry.
Calling Microphone.names
requires an extensive examination of the hardware, and it
may take several seconds to build the array. In most cases, you can just use the default microphone.
Note: To determine the name of the current microphone,
use the name
property.
See also
noiseSuppressionLevel | property |
noiseSuppressionLevel:int
Runtime Versions: | 2 |
Maximum attenuation of the noise in dB (negative number) used for Speex encoder. If enabled, noise suppression is applied to sound captured from Microphone before Speex compression. Set to 0 to disable noise suppression. Noise suppression is enabled by default with maximum attenuation of -30 dB. Ignored when Nellymoser codec is selected.
rate | property |
rate:int
Runtime Versions: | AIR 1.0, |
The rate at which the microphone is capturing sound, in kHz. Acceptable values are 5, 8, 11, 22, and 44. The default value is 8 kHz if your sound capture device supports this value. Otherwise, the default value is the next available capture level above 8 kHz that your sound capture device supports, usually 11 kHz.
Note: The actual rate differs slightly from the rate
value, as noted
in the following table:
rate value | Actual frequency |
---|---|
44 | 44,100 Hz |
22 | 22,050 Hz |
11 | 11,025 Hz |
8 | 8,000 Hz |
5 | 5,512 Hz |
See also
silenceLevel | property |
silenceLevel:Number
[read-only] Runtime Versions: | AIR 1.0, |
The amount of sound required to activate the microphone and dispatch
the activity
event. The default value is 10.
See also
silenceTimeout | property |
silenceTimeout:int
[read-only] Runtime Versions: | AIR 1.0, |
The number of milliseconds between the time the microphone stops
detecting sound and the time the activity
event is dispatched. The default
value is 2000 (2 seconds).
To set this value, use the Microphone.setSilenceLevel()
method.
See also
soundTransform | property |
soundTransform:flash.media:SoundTransform
Runtime Versions: | AIR 1.0, |
Controls the sound of this microphone object when it is in loopback mode.
useEchoSuppression | property |
useEchoSuppression:Boolean
[read-only] Runtime Versions: | AIR 1.0, |
Set to true
if echo suppression is enabled; false
otherwise. The default value is
false
unless the user has selected Reduce Echo in the Flash Player Microphone Settings panel.
See also
getEnhancedMicrophone | () | method |
public function getEnhancedMicrophone(index:int = -1):Microphone
Runtime Versions: | 2.7 |
Returns a reference to an enhanced Microphone object that can perform acoustic echo cancellation. Use acoustic echo cancellation to create audio/video chat applications that don't require headsets.
The index
parameter for the Microphone.getEnhancedMicrophone()
method and the Microphone.getMicrophone()
method work the same way.
Important: At any given time you can have only a single instance of enhanced microphone device.
All other Microphone instances stop providing audio data and receive a StatusEvent
with the
code
property Microphone.Unavailable
. When enhanced audio fails to initialize,
calls to this method return null
, setting a value for Microphone.enhancedOptions
has no effect,
and all existing Microphone instances function as before.
To configure an enhanced Microphone object, set the Microphone.enhancedOptions
property. The following
code uses an enhanced Microphone object and full-duplex acoustic echo cancellation in a local test:
var mic:Microphone = Microphone.getEnhancedMicrophone(); var options:MicrophoneEnhancedOptions = new MicrophoneEnhancedOptions(); options.mode = MicrophoneEnhancedMode.FULL_DUPLEX; mic.enhancedOptions = options; mic.setLoopBack(true);
The setUseEchoSuppression()
method is ignored when using acoustic echo cancellation.
Parameters
index:int (default = -1 ) — The index value of the microphone.
|
Microphone — A reference to a Microphone object for capturing audio. If enhanced audio fails to initialize, returns null .
|
See also
getMicrophone | () | method |
public function getMicrophone(index:int = -1):Microphone
Runtime Versions: | AIR 1.0, |
Returns a reference to a Microphone object for capturing audio.
To begin capturing the audio, you must attach the Microphone
object to a NetStream object (see NetStream.attachAudio()
).
Multiple calls to Microphone.getMicrophone()
reference the same microphone.
Thus, if your code contains the lines
and
mic2 = air.Microphone.getMicrophone()
, both mic1
and mic2
reference the same (default) microphone.
In general, you should not pass a value for index
. Simply call
Microphone.getMicrophone()
to return a reference to the default microphone.
Using the Microphone Settings section in the Flash Player settings panel, the user can specify the default
microphone the application should use. (The user access the Flash Player settings panel by right-clicking
Flash Player content running in a web browser.) If you pass a value for index
, you can
reference a microphone other than the one the user chooses. You can use index
in
rare cases—for example, if your application is capturing audio from two microphones
at the same time. Content running in Adobe AIR also uses the Flash Player setting for the default
microphone.
Use the Microphone.index
property to get the index value of the current
Microphone object. You can then pass this value to other methods of the
Microphone class.
When the user responds to this dialog box, a status
event is dispatched
that indicates the user's response. You can also check the Microphone.muted
property to determine if the user has allowed or denied access to the microphone.
If Microphone.getMicrophone()
returns null
, either the microphone is in use
by another application, or there are no microphones installed on the system. To determine
whether any microphones are installed, use Microphones.names.length
. To display
the Flash Player Microphone Settings panel, which lets the user choose the microphone to be
referenced by Microphone.getMicrophone
, use Security.showSettings()
.
Parameters
index:int (default = -1 ) — The index value of the microphone.
|
Microphone — A reference to a Microphone object for capturing audio.
|
Events
status: — Dispatched when a microphone reports its status.
If the value of the code property is "Microphone.Muted" ,
the user has refused to allow the SWF file access to the user's microphone.
If the value of the code property is "Microphone.Unmuted" ,
the user has allowed the SWF file access to the user's microphone. |
See also
setLoopBack | () | method |
public function setLoopBack(state:Boolean = true):void
Runtime Versions: | AIR 1.0, |
Routes audio captured by a microphone to the local speakers.
Parameters
state:Boolean (default = true )
|
setSilenceLevel | () | method |
public function setSilenceLevel(silenceLevel:Number, timeout:int = -1):void
Runtime Versions: | AIR 1.0, |
Sets the minimum input level that should be considered sound and (optionally) the amount of silent time signifying that silence has actually begun.
- To prevent the microphone from detecting sound at all, pass a value of 100 for
silenceLevel
; theactivity
event is never dispatched. - To determine the amount of sound the microphone is currently detecting, use
Microphone.activityLevel
.
Speex includes voice activity detection (VAD) and automatically reduces bandwidth when no voice is detected. When using the Speex codec, Adobe recommends that you set the silence level to 0.
Activity detection is the ability to detect when audio levels suggest that a person is talking. When someone is not talking, bandwidth can be saved because there is no need to send the associated audio stream. This information can also be used for visual feedback so that users know they (or others) are silent.
Silence values correspond directly to activity values. Complete silence is an activity value of 0. Constant loud noise (as loud as can be registered based on the current gain setting) is an activity value of 100. After gain is appropriately adjusted, your activity value is less than your silence value when you're not talking; when you are talking, the activity value exceeds your silence value.
This method is similar to Camera.setMotionLevel()
; both methods are used to
specify when the activity
event is dispatched. However, these methods have
a significantly different impact on publishing streams:
Camera.setMotionLevel()
is designed to detect motion and does not affect bandwidth usage. Even if a video stream does not detect motion, video is still sent.Microphone.setSilenceLevel()
is designed to optimize bandwidth. When an audio stream is considered silent, no audio data is sent. Instead, a single message is sent, indicating that silence has started.
Parameters
silenceLevel:Number — The amount of sound required to activate the microphone
and dispatch the activity event. Acceptable values range from 0 to 100.
| |
timeout:int (default = -1 ) — The number of milliseconds that must elapse without
activity before Flash Player or Adobe AIR considers sound to have stopped and dispatches the
dispatch event. The default value is 2000 (2 seconds).
(Note: The default value shown
in the signature, -1, is an internal value that indicates to Flash Player or Adobe AIR to use 2000.)
|
See also
setUseEchoSuppression | () | method |
public function setUseEchoSuppression(useEchoSuppression:Boolean):void
Runtime Versions: | AIR 1.0, |
Specifies whether to use the echo suppression feature of the audio codec. The default value is
false
unless the user has selected Reduce Echo in the Flash Player Microphone
Settings panel.
Echo suppression is an effort to reduce the effects of audio feedback, which is caused when
sound going out the speaker is picked up by the microphone on the same system. (This is different
from acoustic echo cancellation, which completely removes the feedback. The setUseEchoSuppression()
method
is ignored when you call the getEnhancedMicrophone()
method to use acoustic echo cancellation.)
Generally, echo suppression is advisable when the sound being captured is played through
speakers — instead of a headset —. If your SWF file allows users to specify the
sound output device, you may want to call Microphone.setUseEchoSuppression(true)
if they indicate they are using speakers and will be using the microphone as well.
Users can also adjust these settings in the Flash Player Microphone Settings panel.
Parameters
useEchoSuppression:Boolean — A Boolean value indicating whether to use echo suppression
(true ) or not (false ).
|
See also
activity | Event |
flash.events.ActivityEvent
property ActivityEvent.type =
flash.events.ActivityEvent.ACTIVITY
Runtime Versions: | AIR 1.0, |
Dispatched when a microphone starts or stops recording due to detected silence.
To specify the amount of sound required to trigger this event
with an activating
property of true
,
or the amount of time that must elapse without sound to
trigger this event with an activating
property of
false
, use Microphone.setSilenceLevel()
.
For a Microphone object to dispatch activity events, the application must be monitoring
the input, either by calling setLoopback( true )
, by listening for
sampleData events, or by attaching the microphone to a NetStream object.
ActivityEvent.ACTIVITY
constant defines the value of the type
property of an activity
event object.
This event has the following properties:
Property | Value |
---|---|
activating | true if the device is activating or false if it is deactivating. |
bubbles | false |
cancelable | false ; there is no default behavior to cancel. |
currentTarget | The object that is actively processing the Event object with an event listener. |
target | The object beginning or ending a session, such as a Camera or Microphone object. |
See also
sampleData | Event |
flash.events.SampleDataEvent
property SampleDataEvent.type =
flash.events.SampleDataEvent.SAMPLE_DATA
Runtime Versions: | 2 |
Dispatched when the microphone has sound data in the buffer.
The Microphone.rate
property determines the number of samples generated
per second. The number of samples per event is a factor of the number of samples
per second and the latency between event calls.
type
property of a SampleDataEvent
event object.
This event has the following properties:
Property | Value |
---|---|
bubbles | false |
cancelable | false ; there is no default behavior to cancel. |
position | The point from which audio data is provided. |
See also
status | Event |
flash.events.StatusEvent
property StatusEvent.type =
flash.events.StatusEvent.STATUS
Runtime Versions: | AIR 1.0, |
Dispatched when a microphone reports its status.
If the value of the code
property is "Microphone.Muted"
,
the user has refused to allow the SWF file access to the microphone.
If the value of the code
property is "Microphone.Unmuted"
,
the user has allowed the SWF file access to the microphone.
Status events are not dispatched in Adobe AIR applications; access to the microphone cannot be changed dynamically. On most platforms, AIR applications can always access the microphone. On Android, an application must specify the Android RECORD_AUDIO permission in the application descriptor. Otherwise, Android denies access to the microphone altogether.
Defines the value of thetype
property of a status
event object.
This event has the following properties:
Property | Value |
---|---|
bubbles | false |
cancelable | false ; there is no default behavior to cancel. |
code | A description of the object's status. |
currentTarget | The object that is actively processing the Event object with an event listener. |
level | The category of the message, such as "status" , "warning" or "error" . |
target | The object reporting its status. |
See also
Thu Sep 29 2011, 02:34 AM -07:00