Added in API level 16

AcousticEchoCanceler


open class AcousticEchoCanceler : AudioEffect

Acoustic Echo Canceler (AEC).

Acoustic Echo Canceler (AEC) is an audio pre-processor which removes the contribution of the signal received from the remote party from the captured audio signal.

AEC is used by voice communication applications (voice chat, video conferencing, SIP calls) where the presence of echo with significant delay in the signal received from the remote party is highly disturbing. AEC is often used in conjunction with noise suppression (NS).

An application creates an AcousticEchoCanceler object to instantiate and control an AEC engine in the audio capture path.

To attach the AcousticEchoCanceler to a particular android.media.AudioRecord, specify the audio session ID of this AudioRecord when creating the AcousticEchoCanceler. The audio session is retrieved by calling android.media.AudioRecord#getAudioSessionId() on the AudioRecord instance.

On some devices, an AEC can be inserted by default in the capture path by the platform according to the android.media.MediaRecorder.AudioSource used. The application should call AcousticEchoCanceler.getEnable() after creating the AEC to check the default AEC activation state on a particular AudioRecord session.

See android.media.audiofx.AudioEffect class for more details on controlling audio effects.

Summary

Inherited 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.

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.

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 android.app.Activity#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.

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.

Int ALREADY_EXISTS

Internal operation status. Not returned by any method.

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.

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.

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.

String EFFECT_POST_PROCESSING

Effect connection mode is post processing. The audio post processing effects are attached to an audio output stream or device

String EFFECT_PRE_PROCESSING

Effect connection mode is pre processing. The audio pre processing effects are attached to an audio input stream or device

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.

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.

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.

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.

Int SUCCESS

Successful operation.

Public methods
open static AcousticEchoCanceler!
create(audioSession: Int)

Creates an AcousticEchoCanceler and attaches it to the AudioRecord on the audio session specified.

open static Boolean

Checks if the device implements acoustic echo cancellation.

Inherited functions
Unit finalize()

AudioEffect.Descriptor! getDescriptor()

Get the effect descriptor.

Boolean getEnabled()

Returns effect enabled state

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)

Boolean hasControl()

Checks if this AudioEffect object is controlling the effect engine.

Array<AudioEffect.Descriptor!>! queryEffects()

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

Unit 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.

Unit setControlStatusListener(listener: AudioEffect.OnControlStatusChangeListener!)

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

Unit setEnableStatusListener(listener: AudioEffect.OnEnableStatusChangeListener!)

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

Int setEnabled(enabled: Boolean)

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.

Inherited properties
UUID! EFFECT_TYPE_AEC

UUID for Acoustic Echo Canceler (AEC)

UUID! EFFECT_TYPE_AGC

UUID for Automatic Gain Control (AGC)

UUID! EFFECT_TYPE_BASS_BOOST

UUID for bass boost effect

UUID! EFFECT_TYPE_DYNAMICS_PROCESSING

UUID for Dynamics Processing

UUID! EFFECT_TYPE_ENV_REVERB

UUID for environmental reverberation effect

UUID! EFFECT_TYPE_EQUALIZER

UUID for equalizer effect

UUID EFFECT_TYPE_HAPTIC_GENERATOR

UUID for Haptic Generator.

UUID! EFFECT_TYPE_LOUDNESS_ENHANCER

UUID for Loudness Enhancer

UUID! EFFECT_TYPE_NS

UUID for Noise Suppressor (NS)

UUID! EFFECT_TYPE_PRESET_REVERB

UUID for preset reverberation effect

UUID! EFFECT_TYPE_VIRTUALIZER

UUID for virtualizer effect

Public methods

create

Added in API level 16
open static fun create(audioSession: Int): AcousticEchoCanceler!

Creates an AcousticEchoCanceler and attaches it to the AudioRecord on the audio session specified.

Parameters
audioSession Int: system wide unique audio session identifier. The AcousticEchoCanceler will be applied to the AudioRecord with the same audio session.
Return
AcousticEchoCanceler! AcousticEchoCanceler created or null if the device does not implement AEC.

isAvailable

Added in API level 16
open static fun isAvailable(): Boolean

Checks if the device implements acoustic echo cancellation.

Return
Boolean true if the device implements acoustic echo cancellation, false otherwise.