Added in API level 4

Summary: Constants | Ctors | Inherited Methods

TextToSpeech.Engine

---

Kotlin |Java

public class TextToSpeech.Engine
extends Object

java.lang.Object
↳	android.speech.tts.TextToSpeech.Engine

---

Constants and parameter names for controlling text-to-speech. These include:

• Intents to ask engine to install data or check its data and extras for a TTS engine's check data activity.
• Keys for the parameters passed with speak commands, e.g. Engine#KEY_PARAM_UTTERANCE_ID, Engine#KEY_PARAM_STREAM.
• A list of feature strings that engines might support, e.g Engine#KEY_FEATURE_NETWORK_SYNTHESIS. These values may be passed in to TextToSpeech#speak and TextToSpeech#synthesizeToFile to modify engine behaviour. The engine can be queried for the set of features it supports through TextToSpeech#getFeatures(java.util.Locale).

Apps targeting Android 11 that use text-to-speech should declare INTENT_ACTION_TTS_SERVICE in the queries elements of their manifest:

 <queries>
   ...
  <intent>
      <action android:name="android.intent.action.TTS_SERVICE" />
  </intent>
 </queries>
 

Summary

Constants
String	ACTION_CHECK_TTS_DATA Activity Action: Starts the activity from the platform TextToSpeech engine to verify the proper installation and availability of the resource files on the system.
String	ACTION_GET_SAMPLE_TEXT Activity intent for getting some sample text to use for demonstrating TTS.
String	ACTION_INSTALL_TTS_DATA Activity Action: Triggers the platform TextToSpeech engine to start the activity that installs the resource files on the device that are required for TTS to be operational.
String	ACTION_TTS_DATA_INSTALLED Broadcast Action: broadcast to signal the change in the list of available languages or/and their features.
int	CHECK_VOICE_DATA_BAD_DATA This constant was deprecated in API level 18. Use CHECK_VOICE_DATA_FAIL instead.
int	CHECK_VOICE_DATA_FAIL Indicates failure when checking the installation status of the resources used by the TextToSpeech engine with the ACTION_CHECK_TTS_DATA intent.
int	CHECK_VOICE_DATA_MISSING_DATA This constant was deprecated in API level 18. Use CHECK_VOICE_DATA_FAIL instead.
int	CHECK_VOICE_DATA_MISSING_VOLUME This constant was deprecated in API level 18. Use CHECK_VOICE_DATA_FAIL instead.
int	CHECK_VOICE_DATA_PASS Indicates success when checking the installation status of the resources used by the TextToSpeech engine with the ACTION_CHECK_TTS_DATA intent.
int	DEFAULT_STREAM Default audio stream used when playing synthesized speech.
String	EXTRA_AVAILABLE_VOICES Extra information received with the ACTION_CHECK_TTS_DATA intent result where the TextToSpeech engine returns an ArrayList of all the available voices.
String	EXTRA_CHECK_VOICE_DATA_FOR This constant was deprecated in API level 18. Redundant functionality, checking for existence of specific sets of voice data can be done on client side.
String	EXTRA_SAMPLE_TEXT Extra information received with the ACTION_GET_SAMPLE_TEXT intent result where the TextToSpeech engine returns an String with sample text for requested voice
String	EXTRA_TTS_DATA_INSTALLED This constant was deprecated in API level 18. No longer in use. If client is interested in information about what changed, it should use the ACTION_CHECK_TTS_DATA intent to discover available voices.
String	EXTRA_UNAVAILABLE_VOICES Extra information received with the ACTION_CHECK_TTS_DATA intent result where the TextToSpeech engine returns an ArrayList of all the unavailable voices.
String	EXTRA_VOICE_DATA_FILES This constant was deprecated in API level 18. TTS engine implementation detail, this information has no use for text-to-speech API client.
String	EXTRA_VOICE_DATA_FILES_INFO This constant was deprecated in API level 18. TTS engine implementation detail, this information has no use for text-to-speech API client.
String	EXTRA_VOICE_DATA_ROOT_DIRECTORY This constant was deprecated in API level 18. TTS engine implementation detail, this information has no use for text-to-speech API client.
String	INTENT_ACTION_TTS_SERVICE Intent for starting a TTS service.
String	KEY_FEATURE_EMBEDDED_SYNTHESIS This constant was deprecated in API level 21. Starting from API level 21, to select embedded synthesis, call (TextToSpeech#getVoices(), find a suitable embedded voice (Voice#isNetworkConnectionRequired()) and pass it to TextToSpeech#setVoice(Voice)).
String	KEY_FEATURE_NETWORK_RETRIES_COUNT Feature key that indicates that network request retries count can be set for the request.
String	KEY_FEATURE_NETWORK_SYNTHESIS This constant was deprecated in API level 21. Starting from API level 21, to select network synthesis, call TextToSpeech#getVoices(), find a suitable network voice (Voice#isNetworkConnectionRequired()) and pass it to TextToSpeech#setVoice(Voice).
String	KEY_FEATURE_NETWORK_TIMEOUT_MS Feature key that indicate that a network timeout can be set for the request.
String	KEY_FEATURE_NOT_INSTALLED Feature key that indicates that the voice may need to download additional data to be fully functional.
String	KEY_PARAM_PAN Parameter key to specify how the speech is panned from left to right when speaking text.
String	KEY_PARAM_SESSION_ID Parameter key to specify an audio session identifier (obtained from AudioManager#generateAudioSessionId()) that will be used by the request audio output.
String	KEY_PARAM_STREAM Parameter key to specify the audio stream type to be used when speaking text or playing back a file.
String	KEY_PARAM_UTTERANCE_ID Parameter key to identify an utterance in the TextToSpeech.OnUtteranceCompletedListener after text has been spoken, a file has been played back or a silence duration has elapsed.
String	KEY_PARAM_VOLUME Parameter key to specify the speech volume relative to the current stream type volume used when speaking text.
String	SERVICE_META_DATA Name under which a text to speech engine publishes information about itself.

Public constructors
Engine()

Inherited methods

From class java.lang.Object Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Constants

ACTION_CHECK_TTS_DATA

Added in API level 4

public static final String ACTION_CHECK_TTS_DATA

Activity Action: Starts the activity from the platform TextToSpeech engine to verify the proper installation and availability of the resource files on the system. Upon completion, the activity will return one of the following codes: CHECK_VOICE_DATA_PASS, CHECK_VOICE_DATA_FAIL,

Moreover, the data received in the activity result will contain the following fields:

• EXTRA_AVAILABLE_VOICES which contains an ArrayList of all the available voices. The format of each voice is: lang-COUNTRY-variant where COUNTRY and variant are optional (ie, "eng" or "eng-USA" or "eng-USA-FEMALE").
• EXTRA_UNAVAILABLE_VOICES which contains an ArrayList of all the unavailable voices (ones that user can install). The format of each voice is: lang-COUNTRY-variant where COUNTRY and variant are optional (ie, "eng" or "eng-USA" or "eng-USA-FEMALE").

Constant Value: "android.speech.tts.engine.CHECK_TTS_DATA"

ACTION_GET_SAMPLE_TEXT

Added in API level 18

public static final String ACTION_GET_SAMPLE_TEXT

Activity intent for getting some sample text to use for demonstrating TTS. Specific locale have to be requested by passing following extra parameters:

• language
• country
• variant

Upon completion, the activity result may contain the following fields:

• EXTRA_SAMPLE_TEXT which contains an String with sample text.

Constant Value: "android.speech.tts.engine.GET_SAMPLE_TEXT"

ACTION_INSTALL_TTS_DATA

Added in API level 4

public static final String ACTION_INSTALL_TTS_DATA

Activity Action: Triggers the platform TextToSpeech engine to start the activity that installs the resource files on the device that are required for TTS to be operational. Since the installation of the data can be interrupted or declined by the user, the application shouldn't expect successful installation upon return from that intent, and if need be, should check installation status with ACTION_CHECK_TTS_DATA.

Constant Value: "android.speech.tts.engine.INSTALL_TTS_DATA"

ACTION_TTS_DATA_INSTALLED

Added in API level 4

public static final String ACTION_TTS_DATA_INSTALLED

Broadcast Action: broadcast to signal the change in the list of available languages or/and their features.

Constant Value: "android.speech.tts.engine.TTS_DATA_INSTALLED"

CHECK_VOICE_DATA_BAD_DATA

Added in API level 4
Deprecated in API level 18

public static final int CHECK_VOICE_DATA_BAD_DATA

This constant was deprecated in API level 18.
Use CHECK_VOICE_DATA_FAIL instead.

Indicates erroneous data when checking the installation status of the resources used by the TextToSpeech engine with the ACTION_CHECK_TTS_DATA intent.

Constant Value: -1 (0xffffffff)

CHECK_VOICE_DATA_FAIL

Added in API level 4

public static final int CHECK_VOICE_DATA_FAIL

Indicates failure when checking the installation status of the resources used by the TextToSpeech engine with the ACTION_CHECK_TTS_DATA intent.

Constant Value: 0 (0x00000000)

CHECK_VOICE_DATA_MISSING_DATA

Added in API level 4
Deprecated in API level 18

public static final int CHECK_VOICE_DATA_MISSING_DATA

This constant was deprecated in API level 18.
Use CHECK_VOICE_DATA_FAIL instead.

Indicates missing resources when checking the installation status of the resources used by the TextToSpeech engine with the ACTION_CHECK_TTS_DATA intent.

Constant Value: -2 (0xfffffffe)

CHECK_VOICE_DATA_MISSING_VOLUME

Added in API level 4
Deprecated in API level 18

public static final int CHECK_VOICE_DATA_MISSING_VOLUME

This constant was deprecated in API level 18.
Use CHECK_VOICE_DATA_FAIL instead.

Indicates missing storage volume when checking the installation status of the resources used by the TextToSpeech engine with the ACTION_CHECK_TTS_DATA intent.

Constant Value: -3 (0xfffffffd)

CHECK_VOICE_DATA_PASS

Added in API level 4

public static final int CHECK_VOICE_DATA_PASS

Indicates success when checking the installation status of the resources used by the TextToSpeech engine with the ACTION_CHECK_TTS_DATA intent.

Constant Value: 1 (0x00000001)

DEFAULT_STREAM

Added in API level 4

public static final int DEFAULT_STREAM

Default audio stream used when playing synthesized speech.

Constant Value: 3 (0x00000003)

EXTRA_AVAILABLE_VOICES

Added in API level 8

public static final String EXTRA_AVAILABLE_VOICES

Extra information received with the ACTION_CHECK_TTS_DATA intent result where the TextToSpeech engine returns an ArrayList of all the available voices. The format of each voice is: lang-COUNTRY-variant where COUNTRY and variant are optional (ie, "eng" or "eng-USA" or "eng-USA-FEMALE").

Constant Value: "availableVoices"

EXTRA_CHECK_VOICE_DATA_FOR

Added in API level 8
Deprecated in API level 18

public static final String EXTRA_CHECK_VOICE_DATA_FOR

This constant was deprecated in API level 18.
Redundant functionality, checking for existence of specific sets of voice data can be done on client side.

Extra information sent with the ACTION_CHECK_TTS_DATA intent where the caller indicates to the TextToSpeech engine which specific sets of voice data to check for by sending an ArrayList of the voices that are of interest. The format of each voice is: lang-COUNTRY-variant where COUNTRY and variant are optional (ie, "eng" or "eng-USA" or "eng-USA-FEMALE").

Constant Value: "checkVoiceDataFor"

EXTRA_SAMPLE_TEXT

Added in API level 18

public static final String EXTRA_SAMPLE_TEXT

Extra information received with the ACTION_GET_SAMPLE_TEXT intent result where the TextToSpeech engine returns an String with sample text for requested voice

Constant Value: "sampleText"

EXTRA_TTS_DATA_INSTALLED

Added in API level 4
Deprecated in API level 18

public static final String EXTRA_TTS_DATA_INSTALLED

This constant was deprecated in API level 18.
No longer in use. If client is interested in information about what changed, it should use the ACTION_CHECK_TTS_DATA intent to discover available voices.

Extra information received with the ACTION_TTS_DATA_INSTALLED intent result. It indicates whether the data files for the synthesis engine were successfully installed. The installation was initiated with the ACTION_INSTALL_TTS_DATA intent. The possible values for this extra are TextToSpeech#SUCCESS and TextToSpeech#ERROR.

Constant Value: "dataInstalled"

EXTRA_UNAVAILABLE_VOICES

Added in API level 8

public static final String EXTRA_UNAVAILABLE_VOICES

Extra information received with the ACTION_CHECK_TTS_DATA intent result where the TextToSpeech engine returns an ArrayList of all the unavailable voices. The format of each voice is: lang-COUNTRY-variant where COUNTRY and variant are optional (ie, "eng" or "eng-USA" or "eng-USA-FEMALE").

Constant Value: "unavailableVoices"

EXTRA_VOICE_DATA_FILES

Added in API level 4
Deprecated in API level 18

public static final String EXTRA_VOICE_DATA_FILES

This constant was deprecated in API level 18.
TTS engine implementation detail, this information has no use for text-to-speech API client.

Extra information received with the ACTION_CHECK_TTS_DATA intent result where the TextToSpeech engine specifies the file names of its resources under the resource path.

Constant Value: "dataFiles"

EXTRA_VOICE_DATA_FILES_INFO

Added in API level 4
Deprecated in API level 18

public static final String EXTRA_VOICE_DATA_FILES_INFO

This constant was deprecated in API level 18.
TTS engine implementation detail, this information has no use for text-to-speech API client.

Extra information received with the ACTION_CHECK_TTS_DATA intent result where the TextToSpeech engine specifies the locale associated with each resource file.

Constant Value: "dataFilesInfo"

EXTRA_VOICE_DATA_ROOT_DIRECTORY

Added in API level 4
Deprecated in API level 18

public static final String EXTRA_VOICE_DATA_ROOT_DIRECTORY

This constant was deprecated in API level 18.
TTS engine implementation detail, this information has no use for text-to-speech API client.

Extra information received with the ACTION_CHECK_TTS_DATA intent result where the TextToSpeech engine specifies the path to its resources. It may be used by language packages to find out where to put their data.

Constant Value: "dataRoot"

INTENT_ACTION_TTS_SERVICE

Added in API level 14

public static final String INTENT_ACTION_TTS_SERVICE

Intent for starting a TTS service. Services that handle this intent must extend TextToSpeechService. Normal applications should not use this intent directly, instead they should talk to the TTS service using the the methods in this class.

Constant Value: "android.intent.action.TTS_SERVICE"

KEY_FEATURE_EMBEDDED_SYNTHESIS

Added in API level 15
Deprecated in API level 21

public static final String KEY_FEATURE_EMBEDDED_SYNTHESIS

This constant was deprecated in API level 21.
Starting from API level 21, to select embedded synthesis, call (TextToSpeech#getVoices(), find a suitable embedded voice (Voice#isNetworkConnectionRequired()) and pass it to TextToSpeech#setVoice(Voice)).

Feature key for embedded synthesis. See TextToSpeech#getFeatures(Locale) for a description of how feature keys work. If set and supported by the engine as per TextToSpeech#getFeatures(Locale), the engine must synthesize text on-device (without making network requests).

See also:

• TextToSpeech.speak(CharSequence, int, Bundle, String)
• TextToSpeech.synthesizeToFile(String, java.util.HashMap, String)
• TextToSpeech.getFeatures(java.util.Locale)

Constant Value: "embeddedTts"

KEY_FEATURE_NETWORK_RETRIES_COUNT

Added in API level 21

public static final String KEY_FEATURE_NETWORK_RETRIES_COUNT

Feature key that indicates that network request retries count can be set for the request. If set and supported as per TextToSpeech#getFeatures(Locale) or Voice#getFeatures(), it can be used as a request parameter to set the number of network request retries that are attempted in case of failure. When used as a key of a request parameter, its value should be a string with an integer value.

See also:

• TextToSpeech.getFeatures(java.util.Locale)
• Voice.getFeatures()

Constant Value: "networkRetriesCount"

KEY_FEATURE_NETWORK_SYNTHESIS

Added in API level 15
Deprecated in API level 21

public static final String KEY_FEATURE_NETWORK_SYNTHESIS

This constant was deprecated in API level 21.
Starting from API level 21, to select network synthesis, call TextToSpeech#getVoices(), find a suitable network voice (Voice#isNetworkConnectionRequired()) and pass it to TextToSpeech#setVoice(Voice).

Feature key for network synthesis. See TextToSpeech#getFeatures(Locale) for a description of how feature keys work. If set (and supported by the engine as per TextToSpeech#getFeatures(Locale), the engine must use network based synthesis.

See also:

• TextToSpeech.speak(CharSequence, int, Bundle, String)
• TextToSpeech.synthesizeToFile(String, java.util.HashMap, String)
• TextToSpeech.getFeatures(java.util.Locale)

Constant Value: "networkTts"

KEY_FEATURE_NETWORK_TIMEOUT_MS

Added in API level 21

public static final String KEY_FEATURE_NETWORK_TIMEOUT_MS

Feature key that indicate that a network timeout can be set for the request. If set and supported as per TextToSpeech#getFeatures(Locale) or Voice#getFeatures(), it can be used as request parameter to set the maximum allowed time for a single request attempt, in milliseconds, before synthesis fails. When used as a key of a request parameter, its value should be a string with an integer value.

See also:

• TextToSpeech.getFeatures(java.util.Locale)
• Voice.getFeatures()

Constant Value: "networkTimeoutMs"

KEY_FEATURE_NOT_INSTALLED

Added in API level 21

public static final String KEY_FEATURE_NOT_INSTALLED

Feature key that indicates that the voice may need to download additional data to be fully functional. The download will be triggered by calling TextToSpeech#setVoice(Voice) or TextToSpeech#setLanguage(Locale). Until download is complete, each synthesis request will either report TextToSpeech#ERROR_NOT_INSTALLED_YET error, or use a different voice to synthesize the request. This feature should NOT be used as a key of a request parameter.

See also:

• TextToSpeech.getFeatures(java.util.Locale)
• Voice.getFeatures()

Constant Value: "notInstalled"

KEY_PARAM_PAN

Added in API level 11

public static final String KEY_PARAM_PAN

Parameter key to specify how the speech is panned from left to right when speaking text. Pan is specified as a float ranging from -1 to +1 where -1 maps to a hard-left pan, 0 to center (the default behavior), and +1 to hard-right.

See also:

• TextToSpeech.speak(CharSequence, int, Bundle, String)
• TextToSpeech.playEarcon(String, int, HashMap)

Constant Value: "pan"

KEY_PARAM_SESSION_ID

Added in API level 21

public static final String KEY_PARAM_SESSION_ID

Parameter key to specify an audio session identifier (obtained from AudioManager#generateAudioSessionId()) that will be used by the request audio output. It can be used to associate one of the AudioEffect objects with the synthesis (or earcon) output.

See also:

• TextToSpeech.speak(CharSequence, int, Bundle, String)
• TextToSpeech.playEarcon(String, int, HashMap)

Constant Value: "sessionId"

KEY_PARAM_STREAM

Added in API level 4

public static final String KEY_PARAM_STREAM

Parameter key to specify the audio stream type to be used when speaking text or playing back a file. The value should be one of the STREAM_ constants defined in AudioManager.

See also:

• TextToSpeech.speak(CharSequence, int, Bundle, String)
• TextToSpeech.playEarcon(String, int, HashMap)

Constant Value: "streamType"

KEY_PARAM_UTTERANCE_ID

Added in API level 4

public static final String KEY_PARAM_UTTERANCE_ID

Parameter key to identify an utterance in the TextToSpeech.OnUtteranceCompletedListener after text has been spoken, a file has been played back or a silence duration has elapsed.

See also:

• TextToSpeech.speak(CharSequence, int, Bundle, String)
• TextToSpeech.playEarcon(String, int, HashMap)
• TextToSpeech.synthesizeToFile(String, HashMap, String)

Constant Value: "utteranceId"

KEY_PARAM_VOLUME

Added in API level 11

public static final String KEY_PARAM_VOLUME

Parameter key to specify the speech volume relative to the current stream type volume used when speaking text. Volume is specified as a float ranging from 0 to 1 where 0 is silence, and 1 is the maximum volume (the default behavior).

See also:

• TextToSpeech.speak(CharSequence, int, Bundle, String)
• TextToSpeech.playEarcon(String, int, HashMap)

Constant Value: "volume"

SERVICE_META_DATA

Added in API level 14

public static final String SERVICE_META_DATA

Name under which a text to speech engine publishes information about itself. This meta-data should reference an XML resource containing a <tts-engine> tag.

Constant Value: "android.speech.tts"

Public constructors

Engine

public Engine ()