Equalizer

Kotlin |Java

open class Equalizer : AudioEffect

kotlin.Any
↳	android.media.audiofx.AudioEffect
	↳	android.media.audiofx.Equalizer

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	`OnParameterChangeListener` The OnParameterChangeListener interface defines a method called by the Equalizer when a parameter value has changed.
open	`Settings` The Settings class regroups all equalizer parameters.

Constants
static Int	`PARAM_BAND_FREQ_RANGE` Band frequency range.
static Int	`PARAM_BAND_LEVEL` Band level.
static Int	`PARAM_CENTER_FREQ` Band center frequency.
static Int	`PARAM_CURRENT_PRESET` Current preset.
static Int	`PARAM_GET_BAND` Band for a given frequency.
static Int	`PARAM_GET_NUM_OF_PRESETS` Request number of presets.
static Int	`PARAM_GET_PRESET_NAME` Request preset name.
static Int	`PARAM_LEVEL_RANGE` Band level range.
static Int	`PARAM_NUM_BANDS` Number of bands.
static Int	`PARAM_STRING_SIZE_MAX` Maximum size for preset name

Inherited constants

From class AudioEffect

`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: `CONTENT_TYPE_MUSIC` `CONTENT_TYPE_MOVIE` `CONTENT_TYPE_GAME` `CONTENT_TYPE_VOICE` 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!	`getBandFreqRange(band: Short)` Gets the frequency range of the given frequency band.
open Short	`getBandLevel(band: Short)` Gets the gain set for the given equalizer band.
open ShortArray!	`getBandLevelRange()` Gets the level range for use by `setBandLevel(short,short)`.
open Int	`getCenterFreq(band: Short)` Gets the center frequency of the given band.
open Short	`getCurrentPreset()` Gets current preset.
open Short	`getNumberOfBands()` Gets the number of frequency bands supported by the Equalizer engine.
open Short	`getNumberOfPresets()` Gets the total number of presets the equalizer supports.
open String!	`getPresetName(preset: Short)` Gets the preset name based on the index.
open Equalizer.Settings!	`getProperties()` Gets the equalizer properties.
open Unit	`setBandLevel(band: Short, level: Short)` Sets the given equalizer band to the given gain value.
open Unit	`setParameterListener(listener: Equalizer.OnParameterChangeListener!)` Registers an OnParameterChangeListener interface.
open Unit	`setProperties(settings: Equalizer.Settings!)` Sets the equalizer properties.
open Unit	`usePreset(preset: Short)` Sets the equalizer according to the given preset.

Inherited functions

From class AudioEffect

`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

From class AudioEffect

`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

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`

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.

Equalizer

Summary

Constants

PARAM_BAND_FREQ_RANGE

PARAM_BAND_LEVEL

PARAM_CENTER_FREQ

PARAM_CURRENT_PRESET

PARAM_GET_BAND

PARAM_GET_NUM_OF_PRESETS

PARAM_GET_PRESET_NAME

PARAM_LEVEL_RANGE

PARAM_NUM_BANDS

PARAM_STRING_SIZE_MAX

Public constructors

Equalizer

Public methods

getBand

getBandFreqRange

getBandLevel

getBandLevelRange

getCenterFreq

getCurrentPreset

getNumberOfBands

getNumberOfPresets

getPresetName

getProperties

setBandLevel

setParameterListener

setProperties

usePreset