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.
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 |
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 | |
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Virtualizer(int priority, int audioSession)
Class constructor. |
Public methods | |
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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
|
int PARAM_STRENGTH
Virtualizer effect strength. Parameter ID for
Virtualizer.OnParameterChangeListener
Constant Value: 1 (0x00000001)
int PARAM_STRENGTH_SUPPORTED
Is strength parameter supported by virtualizer engine. Parameter ID for getParameter().
Constant Value: 0 (0x00000000)
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)
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)
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)
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)
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 |
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 |
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 |
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 |
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 |
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:
|
Returns | |
---|---|
boolean |
true if the combination of channel mask and virtualization mode is supported, false otherwise. |
Throws | |
---|---|
|
IllegalStateException |
|
IllegalArgumentException |
UnsupportedOperationException |
|
IllegalStateException |
|
IllegalArgumentException |
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 |
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 |
void setParameterListener (Virtualizer.OnParameterChangeListener listener)
Registers an OnParameterChangeListener interface.
Parameters | |
---|---|
listener |
Virtualizer.OnParameterChangeListener :
OnParameterChangeListener interface registered
|
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 |
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 |