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AudioEffect

public class AudioEffect
extends Object

java.lang.Object
   ↳ android.media.audiofx.AudioEffect
Known Direct Subclasses


AudioEffect is the base class for controlling audio effects provided by the android audio framework.

Applications should not use the AudioEffect class directly but one of its derived classes to control specific effects:

To apply the audio effect to a specific AudioTrack or MediaPlayer instance, the application must specify the audio session ID of that instance when creating the AudioEffect. (see getAudioSessionId() for details on audio sessions).

NOTE: attaching insert effects (equalizer, bass boost, virtualizer) to the global audio output mix by use of session 0 is deprecated.

Creating an AudioEffect object will create the corresponding effect engine in the audio framework if no instance of the same effect type exists in the specified audio session. If one exists, this instance will be used.

The application creating the AudioEffect object (or a derived class) will either receive control of the effect engine or not depending on the priority parameter. If priority is higher than the priority used by the current effect engine owner, the control will be transfered to the new object. Otherwise control will remain with the previous object. In this case, the new application will be notified of changes in effect engine state or control ownership by the appropriate listener.

Summary

Nested classes

class AudioEffect.Descriptor

The effect descriptor contains information on a particular effect implemented in the audio framework:

  • type: UUID identifying the effect type. 

interface AudioEffect.OnControlStatusChangeListener

The OnControlStatusChangeListener interface defines a method called by the AudioEffect when a the control of the effect engine is gained or lost by the application  

interface AudioEffect.OnEnableStatusChangeListener

The OnEnableStatusChangeListener interface defines a method called by the AudioEffect when a the enabled state of the effect engine was changed by the controlling application. 

Constants

String ACTION_CLOSE_AUDIO_EFFECT_CONTROL_SESSION

Intent to signal to the effect control application or service that an audio session is closed and that effects should not be applied anymore.

String ACTION_DISPLAY_AUDIO_EFFECT_CONTROL_PANEL

Intent to launch an audio effect control panel UI.

String ACTION_OPEN_AUDIO_EFFECT_CONTROL_SESSION

Intent to signal to the effect control application or service that a new audio session is opened and requires audio effects to be applied.

int ALREADY_EXISTS

Internal operation status.

int CONTENT_TYPE_GAME

Value for EXTRA_CONTENT_TYPE when the type of content played is game audio

int CONTENT_TYPE_MOVIE

Value for EXTRA_CONTENT_TYPE when the type of content played is video or movie

int CONTENT_TYPE_MUSIC

Value for EXTRA_CONTENT_TYPE when the type of content played is music

int CONTENT_TYPE_VOICE

Value for EXTRA_CONTENT_TYPE when the type of content played is voice audio

String EFFECT_AUXILIARY

Effect connection mode is auxiliary.

String EFFECT_INSERT

Effect connection mode is insert.

int ERROR

Unspecified error.

int ERROR_BAD_VALUE

Operation failed due to bad parameter value.

int ERROR_DEAD_OBJECT

Operation failed due to dead remote object.

int ERROR_INVALID_OPERATION

Operation failed because it was requested in wrong state.

int ERROR_NO_INIT

Operation failed due to bad object initialization.

int ERROR_NO_MEMORY

Operation failed due to lack of memory.

String EXTRA_AUDIO_SESSION

Contains the ID of the audio session the effects should be applied to.

String EXTRA_CONTENT_TYPE

Indicates which type of content is played by the application.

String EXTRA_PACKAGE_NAME

Contains the package name of the calling application.

int SUCCESS

Successful operation.

Fields

public static final UUID EFFECT_TYPE_AEC

UUID for Acoustic Echo Canceler (AEC)

public static final UUID EFFECT_TYPE_AGC

UUID for Automatic Gain Control (AGC)

public static final UUID EFFECT_TYPE_BASS_BOOST

UUID for bass boost effect

public static final UUID EFFECT_TYPE_ENV_REVERB

UUID for environmental reverberation effect

public static final UUID EFFECT_TYPE_EQUALIZER

UUID for equalizer effect

public static final UUID EFFECT_TYPE_LOUDNESS_ENHANCER

UUID for Loudness Enhancer

public static final UUID EFFECT_TYPE_NS

UUID for Noise Suppressor (NS)

public static final UUID EFFECT_TYPE_PRESET_REVERB

UUID for preset reverberation effect

public static final UUID EFFECT_TYPE_VIRTUALIZER

UUID for virtualizer effect

Public methods

AudioEffect.Descriptor getDescriptor()

Get the effect descriptor.

boolean getEnabled()

Returns effect enabled state

int getId()

Returns effect unique identifier.

boolean hasControl()

Checks if this AudioEffect object is controlling the effect engine.

static Descriptor[] queryEffects()

Query all effects available on the platform.

void release()

Releases the native AudioEffect resources.

void setControlStatusListener(AudioEffect.OnControlStatusChangeListener listener)

Sets the listener AudioEffect notifies when the effect engine control is taken or returned.

void setEnableStatusListener(AudioEffect.OnEnableStatusChangeListener listener)

Sets the listener AudioEffect notifies when the effect engine is enabled or disabled.

int setEnabled(boolean enabled)

Enable or disable the effect.

Protected methods

void finalize()

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.

Inherited methods

From class java.lang.Object

Constants

ACTION_CLOSE_AUDIO_EFFECT_CONTROL_SESSION

Added in API level 9
String ACTION_CLOSE_AUDIO_EFFECT_CONTROL_SESSION

Intent to signal to the effect control application or service that an audio session is closed and that effects should not be applied anymore.

The effect control application receiving this intent will delete all effects on this session and store current settings in package specific storage.

The calling package name is indicated by the EXTRA_PACKAGE_NAME extra and the audio session ID by the EXTRA_AUDIO_SESSION extra. Both extras are mandatory.

It is good practice for applications to broadcast this intent when music playback stops and/or when exiting to free system resources consumed by audio effect engines.

Constant Value: "android.media.action.CLOSE_AUDIO_EFFECT_CONTROL_SESSION"

ACTION_DISPLAY_AUDIO_EFFECT_CONTROL_PANEL

Added in API level 9
String ACTION_DISPLAY_AUDIO_EFFECT_CONTROL_PANEL

Intent to launch an audio effect control panel UI.

The goal of this intent is to enable separate implementations of music/media player applications and audio effect control application or services. This will allow platform vendors to offer more advanced control options for standard effects or control for platform specific effects.

The intent carries a number of extras used by the player application to communicate necessary pieces of information to the control panel application.

The calling application must use the startActivityForResult(Intent, int) method to launch the control panel so that its package name is indicated and used by the control panel application to keep track of changes for this particular application.

The EXTRA_AUDIO_SESSION extra will indicate an audio session to which the audio effects should be applied. If no audio session is specified, either one of the follownig will happen:

- If an audio session was previously opened by the calling application with ACTION_OPEN_AUDIO_EFFECT_CONTROL_SESSION intent, the effect changes will be applied to that session.

- If no audio session is opened, the changes will be stored in the package specific storage area and applied whenever a new audio session is opened by this application.

The EXTRA_CONTENT_TYPE extra will help the control panel application customize both the UI layout and the default audio effect settings if none are already stored for the calling application.

Constant Value: "android.media.action.DISPLAY_AUDIO_EFFECT_CONTROL_PANEL"

ACTION_OPEN_AUDIO_EFFECT_CONTROL_SESSION

Added in API level 9
String ACTION_OPEN_AUDIO_EFFECT_CONTROL_SESSION

Intent to signal to the effect control application or service that a new audio session is opened and requires audio effects to be applied.

This is different from ACTION_DISPLAY_AUDIO_EFFECT_CONTROL_PANEL in that no UI should be displayed in this case. Music player applications can broadcast this intent before starting playback to make sure that any audio effect settings previously selected by the user are applied.

The effect control application receiving this intent will look for previously stored settings for the calling application, create all required audio effects and apply the effect settings to the specified audio session.

The calling package name is indicated by the EXTRA_PACKAGE_NAME extra and the audio session ID by the EXTRA_AUDIO_SESSION extra. Both extras are mandatory.

If no stored settings are found for the calling application, default settings for the content type indicated by EXTRA_CONTENT_TYPE will be applied. The default settings for a given content type are platform specific.

Constant Value: "android.media.action.OPEN_AUDIO_EFFECT_CONTROL_SESSION"

ALREADY_EXISTS

Added in API level 9
int ALREADY_EXISTS

Internal operation status. Not returned by any method.

Constant Value: -2 (0xfffffffe)

CONTENT_TYPE_GAME

Added in API level 9
int CONTENT_TYPE_GAME

Value for EXTRA_CONTENT_TYPE when the type of content played is game audio

Constant Value: 2 (0x00000002)

CONTENT_TYPE_MOVIE

Added in API level 9
int CONTENT_TYPE_MOVIE

Value for EXTRA_CONTENT_TYPE when the type of content played is video or movie

Constant Value: 1 (0x00000001)

CONTENT_TYPE_MUSIC

Added in API level 9
int CONTENT_TYPE_MUSIC

Value for EXTRA_CONTENT_TYPE when the type of content played is music

Constant Value: 0 (0x00000000)

CONTENT_TYPE_VOICE

Added in API level 9
int CONTENT_TYPE_VOICE

Value for EXTRA_CONTENT_TYPE when the type of content played is voice audio

Constant Value: 3 (0x00000003)

EFFECT_AUXILIARY

Added in API level 9
String EFFECT_AUXILIARY

Effect connection mode is auxiliary.

Auxiliary effects must be created on session 0 (global output mix). In order for a MediaPlayer or AudioTrack to be fed into this effect, they must be explicitely attached to this effect and a send level must be specified.

Use the effect ID returned by getId() to designate this particular effect when attaching it to the MediaPlayer or AudioTrack.

Constant Value: "Auxiliary"

EFFECT_INSERT

Added in API level 9
String EFFECT_INSERT

Effect connection mode is insert. Specifying an audio session ID when creating the effect will insert this effect after all players in the same audio session.

Constant Value: "Insert"

ERROR

Added in API level 9
int ERROR

Unspecified error.

Constant Value: -1 (0xffffffff)

ERROR_BAD_VALUE

Added in API level 9
int ERROR_BAD_VALUE

Operation failed due to bad parameter value.

Constant Value: -4 (0xfffffffc)

ERROR_DEAD_OBJECT

Added in API level 9
int ERROR_DEAD_OBJECT

Operation failed due to dead remote object.

Constant Value: -7 (0xfffffff9)

ERROR_INVALID_OPERATION

Added in API level 9
int ERROR_INVALID_OPERATION

Operation failed because it was requested in wrong state.

Constant Value: -5 (0xfffffffb)

ERROR_NO_INIT

Added in API level 9
int ERROR_NO_INIT

Operation failed due to bad object initialization.

Constant Value: -3 (0xfffffffd)

ERROR_NO_MEMORY

Added in API level 9
int ERROR_NO_MEMORY

Operation failed due to lack of memory.

Constant Value: -6 (0xfffffffa)

EXTRA_AUDIO_SESSION

Added in API level 9
String EXTRA_AUDIO_SESSION

Contains the ID of the audio session the effects should be applied to.

This extra is for use with ACTION_DISPLAY_AUDIO_EFFECT_CONTROL_PANEL, ACTION_OPEN_AUDIO_EFFECT_CONTROL_SESSION and ACTION_CLOSE_AUDIO_EFFECT_CONTROL_SESSION intents.

The extra value is of type int and is the audio session ID.

See also:

Constant Value: "android.media.extra.AUDIO_SESSION"

EXTRA_CONTENT_TYPE

Added in API level 9
String EXTRA_CONTENT_TYPE

Indicates which type of content is played by the application.

This extra is for use with ACTION_DISPLAY_AUDIO_EFFECT_CONTROL_PANEL and ACTION_OPEN_AUDIO_EFFECT_CONTROL_SESSION intents.

This information is used by the effect control application to customize UI and select appropriate default effect settings. The content type is one of the following:

If omitted, the content type defaults to CONTENT_TYPE_MUSIC.

Constant Value: "android.media.extra.CONTENT_TYPE"

EXTRA_PACKAGE_NAME

Added in API level 9
String EXTRA_PACKAGE_NAME

Contains the package name of the calling application.

This extra is for use with ACTION_OPEN_AUDIO_EFFECT_CONTROL_SESSION and ACTION_CLOSE_AUDIO_EFFECT_CONTROL_SESSION intents.

The extra value is a string containing the full package name.

Constant Value: "android.media.extra.PACKAGE_NAME"

SUCCESS

Added in API level 9
int SUCCESS

Successful operation.

Constant Value: 0 (0x00000000)

Fields

EFFECT_TYPE_AEC

Added in API level 18
UUID EFFECT_TYPE_AEC

UUID for Acoustic Echo Canceler (AEC)

EFFECT_TYPE_AGC

Added in API level 18
UUID EFFECT_TYPE_AGC

UUID for Automatic Gain Control (AGC)

EFFECT_TYPE_BASS_BOOST

Added in API level 18
UUID EFFECT_TYPE_BASS_BOOST

UUID for bass boost effect

EFFECT_TYPE_ENV_REVERB

Added in API level 18
UUID EFFECT_TYPE_ENV_REVERB

UUID for environmental reverberation effect

EFFECT_TYPE_EQUALIZER

Added in API level 18
UUID EFFECT_TYPE_EQUALIZER

UUID for equalizer effect

EFFECT_TYPE_LOUDNESS_ENHANCER

Added in API level 19
UUID EFFECT_TYPE_LOUDNESS_ENHANCER

UUID for Loudness Enhancer

EFFECT_TYPE_NS

Added in API level 18
UUID EFFECT_TYPE_NS

UUID for Noise Suppressor (NS)

EFFECT_TYPE_PRESET_REVERB

Added in API level 18
UUID EFFECT_TYPE_PRESET_REVERB

UUID for preset reverberation effect

EFFECT_TYPE_VIRTUALIZER

Added in API level 18
UUID EFFECT_TYPE_VIRTUALIZER

UUID for virtualizer effect

Public methods

getDescriptor

Added in API level 9
AudioEffect.Descriptor getDescriptor ()

Get the effect descriptor.

Returns
AudioEffect.Descriptor
Throws
IllegalStateException

See also:

getEnabled

Added in API level 9
boolean getEnabled ()

Returns effect enabled state

Returns
boolean true if the effect is enabled, false otherwise.
Throws
IllegalStateException

getId

Added in API level 9
int getId ()

Returns effect unique identifier. This system wide unique identifier can be used to attach this effect to a MediaPlayer or an AudioTrack when the effect is an auxiliary effect (Reverb)

Returns
int the effect identifier.
Throws
IllegalStateException

hasControl

Added in API level 9
boolean hasControl ()

Checks if this AudioEffect object is controlling the effect engine.

Returns
boolean true if this instance has control of effect engine, false otherwise.
Throws
IllegalStateException

queryEffects

Added in API level 9
Descriptor[] queryEffects ()

Query all effects available on the platform. Returns an array of AudioEffect.Descriptor objects

Returns
Descriptor[]
Throws
IllegalStateException

release

Added in API level 9
void release ()

Releases the native AudioEffect resources. It is a good practice to release the effect engine when not in use as control can be returned to other applications or the native resources released.

setControlStatusListener

Added in API level 9
void setControlStatusListener (AudioEffect.OnControlStatusChangeListener listener)

Sets the listener AudioEffect notifies when the effect engine control is taken or returned.

setEnableStatusListener

Added in API level 9
void setEnableStatusListener (AudioEffect.OnEnableStatusChangeListener listener)

Sets the listener AudioEffect notifies when the effect engine is enabled or disabled.

setEnabled

Added in API level 9
int setEnabled (boolean enabled)

Enable or disable the effect. Creating an audio effect does not automatically apply this effect on the audio source. It creates the resources necessary to process this effect but the audio signal is still bypassed through the effect engine. Calling this method will make that the effect is actually applied or not to the audio content being played in the corresponding audio session.

Parameters
enabled boolean: the requested enable state
Returns
int SUCCESS in case of success, ERROR_INVALID_OPERATION or ERROR_DEAD_OBJECT in case of failure.
Throws
IllegalStateException

Protected methods

finalize

Added in API level 9
void finalize ()

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. A subclass overrides the finalize method to dispose of system resources or to perform other cleanup.

The general contract of finalize is that it is invoked if and when the JavaTM virtual machine has determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, except as a result of an action taken by the finalization of some other object or class which is ready to be finalized. The finalize method may take any action, including making this object available again to other threads; the usual purpose of finalize, however, is to perform cleanup actions before the object is irrevocably discarded. For example, the finalize method for an object that represents an input/output connection might perform explicit I/O transactions to break the connection before the object is permanently discarded.

The finalize method of class Object performs no special action; it simply returns normally. Subclasses of Object may override this definition.

The Java programming language does not guarantee which thread will invoke the finalize method for any given object. It is guaranteed, however, that the thread that invokes finalize will not be holding any user-visible synchronization locks when finalize is invoked. If an uncaught exception is thrown by the finalize method, the exception is ignored and finalization of that object terminates.

After the finalize method has been invoked for an object, no further action is taken until the Java virtual machine has again determined that there is no longer any means by which this object can be accessed by any thread that has not yet died, including possible actions by other objects or classes which are ready to be finalized, at which point the object may be discarded.

The finalize method is never invoked more than once by a Java virtual machine for any given object.

Any exception thrown by the finalize method causes the finalization of this object to be halted, but is otherwise ignored.

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