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Virtualizer

public class Virtualizer
extends AudioEffect

java.lang.Object
   ↳ android.media.audiofx.AudioEffect
     ↳ android.media.audiofx.Virtualizer


An audio virtualizer is a general name for an effect to spatialize audio channels. The exact behavior of this effect is dependent on the number of audio input channels and the types and number of audio output channels of the device. For example, in the case of a stereo input and stereo headphone output, a stereo widening effect is used when this effect is turned on.

An application creates a Virtualizer object to instantiate and control a virtualizer engine in the audio framework.

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

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

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

See getAudioSessionId() for details on audio sessions.

See AudioEffect class for more details on controlling audio effects.

Summary

Nested classes

interface Virtualizer.OnParameterChangeListener

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

class Virtualizer.Settings

The Settings class regroups all virtualizer parameters. 

Constants

int PARAM_STRENGTH

Virtualizer effect strength.

int PARAM_STRENGTH_SUPPORTED

Is strength parameter supported by virtualizer engine.

int VIRTUALIZATION_MODE_AUTO

A virtualization mode used to indicate the virtualizer effect must stop forcing the processing to a particular mode in forceVirtualizationMode(int).

int VIRTUALIZATION_MODE_BINAURAL

A virtualization mode typically used over headphones.

int VIRTUALIZATION_MODE_OFF

A virtualization mode indicating virtualization processing is not active.

int VIRTUALIZATION_MODE_TRANSAURAL

A virtualization mode typically used over speakers.

Inherited constants

From class android.media.audiofx.AudioEffect

Inherited fields

From class android.media.audiofx.AudioEffect

Public constructors

Virtualizer(int priority, int audioSession)

Class constructor.

Public methods

boolean canVirtualize(int inputChannelMask, int virtualizationMode)

Checks if the combination of a channel mask and virtualization mode is supported by this virtualizer.

boolean forceVirtualizationMode(int virtualizationMode)

Forces the virtualizer effect to use the given processing mode.

Virtualizer.Settings getProperties()

Gets the virtualizer properties.

short getRoundedStrength()

Gets the current strength of the effect.

boolean getSpeakerAngles(int inputChannelMask, int virtualizationMode, int[] angles)

Queries the virtual speaker angles (azimuth and elevation) for a combination of a channel mask and virtualization mode.

boolean getStrengthSupported()

Indicates whether setting strength is supported.

int getVirtualizationMode()

Return the virtualization mode being used, if any.

void setParameterListener(Virtualizer.OnParameterChangeListener listener)

Registers an OnParameterChangeListener interface.

void setProperties(Virtualizer.Settings settings)

Sets the virtualizer properties.

void setStrength(short strength)

Sets the strength of the virtualizer effect.

Inherited methods

From class android.media.audiofx.AudioEffect
From class java.lang.Object

Constants

PARAM_STRENGTH

Added in API level 9
int PARAM_STRENGTH

Virtualizer effect strength. Parameter ID for Virtualizer.OnParameterChangeListener

Constant Value: 1 (0x00000001)

PARAM_STRENGTH_SUPPORTED

Added in API level 9
int PARAM_STRENGTH_SUPPORTED

Is strength parameter supported by virtualizer engine. Parameter ID for getParameter().

Constant Value: 0 (0x00000000)

VIRTUALIZATION_MODE_AUTO

Added in API level 21
int VIRTUALIZATION_MODE_AUTO

A virtualization mode used to indicate the virtualizer effect must stop forcing the processing to a particular mode in forceVirtualizationMode(int).

Constant Value: 1 (0x00000001)

VIRTUALIZATION_MODE_BINAURAL

Added in API level 21
int VIRTUALIZATION_MODE_BINAURAL

A virtualization mode typically used over headphones. Binaural virtualization describes an audio processing configuration for virtualization where the left and right channels are respectively reaching the left and right ear of the user, without also feeding the opposite ear (as is the case when listening over speakers).

Such a mode is therefore meant to be used when audio is playing over stereo wired headphones or headsets, but also stereo headphones through a wireless A2DP Bluetooth link.

See canVirtualize(int, int) to verify this mode is supported by this Virtualizer.

Constant Value: 2 (0x00000002)

VIRTUALIZATION_MODE_OFF

Added in API level 21
int VIRTUALIZATION_MODE_OFF

A virtualization mode indicating virtualization processing is not active. See getVirtualizationMode() as one of the possible return value.

Constant Value: 0 (0x00000000)

VIRTUALIZATION_MODE_TRANSAURAL

Added in API level 21
int VIRTUALIZATION_MODE_TRANSAURAL

A virtualization mode typically used over speakers. Transaural virtualization describes an audio processing configuration that differs from binaural (as described in VIRTUALIZATION_MODE_BINAURAL in that cross-talk is present, i.e. audio played from the left channel also reaches the right ear of the user, and vice-versa.

When supported, such a mode is therefore meant to be used when audio is playing over the built-in stereo speakers of a device, if they are featured.

See canVirtualize(int, int) to verify this mode is supported by this Virtualizer.

Constant Value: 3 (0x00000003)

Public constructors

Virtualizer

Added in API level 9
Virtualizer (int priority, 
                int audioSession)

Class constructor.

Parameters
priority int: the priority level requested by the application for controlling the Virtualizer 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 Virtualizer will be attached to the MediaPlayer or AudioTrack in the same audio session.
Throws
java.lang.IllegalStateException
java.lang.IllegalArgumentException
java.lang.UnsupportedOperationException
RuntimeException
IllegalStateException
IllegalArgumentException
UnsupportedOperationException

Public methods

canVirtualize

Added in API level 21
boolean canVirtualize (int inputChannelMask, 
                int virtualizationMode)

Checks if the combination of a channel mask and virtualization mode is supported by this virtualizer. Some virtualizer implementations may only support binaural processing (i.e. only support headphone output, see VIRTUALIZATION_MODE_BINAURAL), some may support transaural processing (i.e. for speaker output, see VIRTUALIZATION_MODE_TRANSAURAL) for the built-in speakers. Use this method to query the virtualizer implementation capabilities.

Parameters
inputChannelMask int: the channel mask of the content to virtualize.
virtualizationMode int: the mode for which virtualization processing is to be performed, one of VIRTUALIZATION_MODE_BINAURAL, VIRTUALIZATION_MODE_TRANSAURAL.
Returns
boolean true if the combination of channel mask and virtualization mode is supported, false otherwise.
An indication that a certain channel mask is not supported doesn't necessarily mean you cannot play content with that channel mask, it more likely implies the content will be downmixed before being virtualized. For instance a virtualizer that only supports a mask such as CHANNEL_OUT_STEREO will still be able to process content with a mask of CHANNEL_OUT_5POINT1, but will downmix the content to stereo first, and then will virtualize, as opposed to virtualizing each channel individually.
Throws
IllegalStateException
IllegalArgumentException
UnsupportedOperationException
IllegalStateException
IllegalArgumentException

forceVirtualizationMode

Added in API level 21
boolean forceVirtualizationMode (int virtualizationMode)

Forces the virtualizer effect to use the given processing mode. The effect must be enabled for the forced mode to be applied.

Parameters
virtualizationMode int: one of VIRTUALIZATION_MODE_BINAURAL, VIRTUALIZATION_MODE_TRANSAURAL to force a particular processing mode, or .VIRTUALIZATION_MODE_AUTO to stop forcing a mode.
Returns
boolean true if the processing mode is supported, and it is successfully set, or forcing was successfully disabled, false otherwise.
Throws
IllegalStateException
IllegalArgumentException
UnsupportedOperationException
IllegalStateException
IllegalArgumentException

getProperties

Added in API level 9
Virtualizer.Settings getProperties ()

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

Returns
Virtualizer.Settings a Virtualizer.Settings object containing all current parameters values
Throws
IllegalStateException
IllegalArgumentException
UnsupportedOperationException
IllegalStateException
IllegalArgumentException

getRoundedStrength

Added in API level 9
short getRoundedStrength ()

Gets the current strength of the effect.

Returns
short the strength of the effect. The valid range for strength is [0, 1000], where 0 per mille designates the mildest effect and 1000 per mille the strongest
Throws
IllegalStateException
IllegalArgumentException
UnsupportedOperationException
IllegalStateException
IllegalArgumentException

getSpeakerAngles

Added in API level 21
boolean getSpeakerAngles (int inputChannelMask, 
                int virtualizationMode, 
                int[] angles)

Queries the virtual speaker angles (azimuth and elevation) for a combination of a channel mask and virtualization mode. If the virtualization configuration (mask and mode) is supported (see canVirtualize(int, int), the array angles will contain upon return the definition of each virtual speaker and its azimuth and elevation angles relative to the listener.
Note that in some virtualizer implementations, the angles may be strength-dependent.

Parameters
inputChannelMask int: the channel mask of the content to virtualize.
virtualizationMode int: the mode for which virtualization processing is to be performed, one of VIRTUALIZATION_MODE_BINAURAL, VIRTUALIZATION_MODE_TRANSAURAL.
angles int: a non-null array whose length is 3 times the number of channels in the channel mask. If the method indicates the configuration is supported, the array will contain upon return triplets of values: for each channel i among the channels of the mask:
  • the element at index 3*i in the array contains the speaker identification (e.g. CHANNEL_OUT_FRONT_LEFT),
  • the element at index 3*i+1 contains its corresponding azimuth angle expressed in degrees, where 0 is the direction the listener faces, 180 is behind the listener, and -90 is to her/his left,
  • the element at index 3*i+2 contains its corresponding elevation angle where +90 is directly above the listener, 0 is the horizontal plane, and -90 is directly below the listener.
Returns
boolean true if the combination of channel mask and virtualization mode is supported, false otherwise.
Throws
IllegalStateException
IllegalArgumentException
UnsupportedOperationException
IllegalStateException
IllegalArgumentException

getStrengthSupported

Added in API level 9
boolean getStrengthSupported ()

Indicates whether setting strength is supported. If this method returns false, only one strength is supported and the setStrength() method always rounds to that value.

Returns
boolean true is strength parameter is supported, false otherwise

getVirtualizationMode

Added in API level 21
int getVirtualizationMode ()

Return the virtualization mode being used, if any.

Returns
int the virtualization mode being used. If virtualization is not active, the virtualization mode will be VIRTUALIZATION_MODE_OFF. Otherwise the value will be VIRTUALIZATION_MODE_BINAURAL or VIRTUALIZATION_MODE_TRANSAURAL. Virtualization may not be active either because the effect is not enabled or because the current output device is not compatible with this virtualization implementation.
Throws
IllegalStateException
UnsupportedOperationException
IllegalStateException

setParameterListener

Added in API level 9
void setParameterListener (Virtualizer.OnParameterChangeListener listener)

Registers an OnParameterChangeListener interface.

Parameters
listener Virtualizer.OnParameterChangeListener: OnParameterChangeListener interface registered

setProperties

Added in API level 9
void setProperties (Virtualizer.Settings settings)

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

Parameters
settings Virtualizer.Settings: a Virtualizer.Settings object containing the properties to apply
Throws
IllegalStateException
IllegalArgumentException
UnsupportedOperationException
IllegalStateException
IllegalArgumentException

setStrength

Added in API level 9
void setStrength (short strength)

Sets the strength of the virtualizer effect. If the implementation does not support per mille accuracy for setting the strength, it is allowed to round the given strength to the nearest supported value. You can use the getRoundedStrength() method to query the (possibly rounded) value that was actually set.

Parameters
strength short: strength of the effect. The valid range for strength strength is [0, 1000], where 0 per mille designates the mildest effect and 1000 per mille designates the strongest.
Throws
IllegalStateException
IllegalArgumentException
UnsupportedOperationException
IllegalStateException
IllegalArgumentException
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