Added in API level 9

Equalizer


open class Equalizer : AudioEffect

An Equalizer is used to alter the frequency response of a particular music source or of the main output mix.

An application creates an Equalizer object to instantiate and control an Equalizer engine in the audio framework. The application can either simply use predefined presets or have a more precise control of the gain in each frequency band controlled by the equalizer.

The methods, parameter types and units exposed by the Equalizer implementation are directly mapping those defined by the OpenSL ES 1.0.1 Specification (http://www.khronos.org/opensles/) for the SLEqualizerItf interface. Please refer to this specification for more details.

To attach the Equalizer to a particular AudioTrack or MediaPlayer, specify the audio session ID of this AudioTrack or MediaPlayer when constructing the Equalizer.

NOTE: attaching an Equalizer to the global audio output mix by use of session 0 is deprecated.

See android.media.MediaPlayer#getAudioSessionId() for details on audio sessions.

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

Summary

Nested classes
abstract

The OnParameterChangeListener interface defines a method called by the Equalizer when a parameter value has changed.

open

The Settings class regroups all equalizer parameters.

Constants
static Int

Band frequency range.

static Int

Band level.

static Int

Band center frequency.

static Int

Current preset.

static Int

Band for a given frequency.

static Int

Request number of presets.

static Int

Request preset name.

static Int

Band level range.

static Int

Number of bands.

static Int

Maximum size for preset name

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 constructors
Equalizer(priority: Int, audioSession: Int)

Class constructor.

Public methods
open Short
getBand(frequency: Int)

Gets the band that has the most effect on the given frequency.

open IntArray!

Gets the frequency range of the given frequency band.

open Short

Gets the gain set for the given equalizer band.

open ShortArray!

Gets the level range for use by setBandLevel(short,short).

open Int

Gets the center frequency of the given band.

open Short

Gets current preset.

open Short

Gets the number of frequency bands supported by the Equalizer engine.

open Short

Gets the total number of presets the equalizer supports.

open String!

Gets the preset name based on the index.

open Equalizer.Settings!

Gets the equalizer properties.

open Unit
setBandLevel(band: Short, level: Short)

Sets the given equalizer band to the given gain value.

open Unit

Registers an OnParameterChangeListener interface.

open Unit

Sets the equalizer properties.

open Unit
usePreset(preset: Short)

Sets the equalizer according to the given preset.

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

Constants

PARAM_BAND_FREQ_RANGE

Added in API level 9
static val PARAM_BAND_FREQ_RANGE: Int

Band frequency range. Parameter ID for android.media.audiofx.Equalizer.OnParameterChangeListener

Value: 4

PARAM_BAND_LEVEL

Added in API level 9
static val PARAM_BAND_LEVEL: Int

Band level. Parameter ID for OnParameterChangeListener

Value: 2

PARAM_CENTER_FREQ

Added in API level 9
static val PARAM_CENTER_FREQ: Int

Band center frequency. Parameter ID for OnParameterChangeListener

Value: 3

PARAM_CURRENT_PRESET

Added in API level 9
static val PARAM_CURRENT_PRESET: Int

Current preset. Parameter ID for OnParameterChangeListener

Value: 6

PARAM_GET_BAND

Added in API level 9
static val PARAM_GET_BAND: Int

Band for a given frequency. Parameter ID for OnParameterChangeListener

Value: 5

PARAM_GET_NUM_OF_PRESETS

Added in API level 9
static val PARAM_GET_NUM_OF_PRESETS: Int

Request number of presets. Parameter ID for OnParameterChangeListener

Value: 7

PARAM_GET_PRESET_NAME

Added in API level 9
static val PARAM_GET_PRESET_NAME: Int

Request preset name. Parameter ID for OnParameterChangeListener

Value: 8

PARAM_LEVEL_RANGE

Added in API level 9
static val PARAM_LEVEL_RANGE: Int

Band level range. Parameter ID for OnParameterChangeListener

Value: 1

PARAM_NUM_BANDS

Added in API level 9
static val PARAM_NUM_BANDS: Int

Number of bands. Parameter ID for OnParameterChangeListener

Value: 0

PARAM_STRING_SIZE_MAX

Added in API level 9
static val PARAM_STRING_SIZE_MAX: Int

Maximum size for preset name

Value: 32

Public constructors

Equalizer

Added in API level 9
Equalizer(
    priority: Int,
    audioSession: Int)

Class constructor.

Parameters
priority Int: the priority level requested by the application for controlling the Equalizer engine. As the same engine can be shared by several applications, this parameter indicates how much the requesting application needs control of effect parameters. The normal priority is 0, above normal is a positive number, below normal a negative number.
audioSession Int: system wide unique audio session identifier. The Equalizer will be attached to the MediaPlayer or AudioTrack in the same audio session.
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException
java.lang.RuntimeException

Public methods

getBand

Added in API level 9
open fun getBand(frequency: Int): Short

Gets the band that has the most effect on the given frequency.

Parameters
frequency Int: frequency in milliHertz which is to be equalized via the returned band.
Return
Short the frequency band that has most effect on the given frequency.
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException

getBandFreqRange

Added in API level 9
open fun getBandFreqRange(band: Short): IntArray!

Gets the frequency range of the given frequency band.

Parameters
band Short: frequency band whose frequency range is requested. The numbering of the bands starts from 0 and ends at (number of bands - 1).
Return
IntArray! the frequency range in millHertz in an array of integers. The first element is the lower limit of the range, the second element the upper limit.
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException

getBandLevel

Added in API level 9
open fun getBandLevel(band: Short): Short

Gets the gain set for the given equalizer band.

Parameters
band Short: frequency band whose gain is requested. The numbering of the bands starts from 0 and ends at (number of bands - 1).
Return
Short the gain in millibels of the given band.
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException

getBandLevelRange

Added in API level 9
open fun getBandLevelRange(): ShortArray!

Gets the level range for use by setBandLevel(short,short). The level is expressed in milliBel.

Return
ShortArray! the band level range in an array of short integers. The first element is the lower limit of the range, the second element the upper limit.
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException

getCenterFreq

Added in API level 9
open fun getCenterFreq(band: Short): Int

Gets the center frequency of the given band.

Parameters
band Short: frequency band whose center frequency is requested. The numbering of the bands starts from 0 and ends at (number of bands - 1).
Return
Int the center frequency in milliHertz
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException

getCurrentPreset

Added in API level 9
open fun getCurrentPreset(): Short

Gets current preset.

Return
Short the preset that is set at the moment.
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException

getNumberOfBands

Added in API level 9
open fun getNumberOfBands(): Short

Gets the number of frequency bands supported by the Equalizer engine.

Return
Short the number of bands
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException

getNumberOfPresets

Added in API level 9
open fun getNumberOfPresets(): Short

Gets the total number of presets the equalizer supports. The presets will have indices [0, number of presets-1].

Return
Short the number of presets the equalizer supports.
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException

getPresetName

Added in API level 9
open fun getPresetName(preset: Short): String!

Gets the preset name based on the index.

Parameters
preset Short: index of the preset. The valid range is [0, number of presets-1].
Return
String! a string containing the name of the given preset.
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException

getProperties

Added in API level 9
open fun getProperties(): Equalizer.Settings!

Gets the equalizer properties. This method is useful when a snapshot of current equalizer settings must be saved by the application.

Return
Equalizer.Settings! an Equalizer.Settings object containing all current parameters values
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException

setBandLevel

Added in API level 9
open fun setBandLevel(
    band: Short,
    level: Short
): Unit

Sets the given equalizer band to the given gain value.

Parameters
band Short: frequency band that will have the new gain. The numbering of the bands starts from 0 and ends at (number of bands - 1).
level Short: new gain in millibels that will be set to the given band. getBandLevelRange() will define the maximum and minimum values.
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException

setParameterListener

Added in API level 9
open fun setParameterListener(listener: Equalizer.OnParameterChangeListener!): Unit

Registers an OnParameterChangeListener interface.

Parameters
listener Equalizer.OnParameterChangeListener!: OnParameterChangeListener interface registered

setProperties

Added in API level 9
open fun setProperties(settings: Equalizer.Settings!): Unit

Sets the equalizer properties. This method is useful when equalizer settings have to be applied from a previous backup.

Parameters
settings Equalizer.Settings!: an Equalizer.Settings object containing the properties to apply
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException

usePreset

Added in API level 9
open fun usePreset(preset: Short): Unit

Sets the equalizer according to the given preset.

Parameters
preset Short: new preset that will be taken into use. The valid range is [0, number of presets-1].
Exceptions
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException