public
interface
SynthesisCallback
| android.speech.tts.SynthesisCallback |
A callback to return speech data synthesized by a text to speech engine.
The engine can provide streaming audio by calling
start(int, int, int), then audioAvailable(byte[], int, int) until all audio has been provided, then finally
done().
error() can be called at any stage in the synthesis process to
indicate that an error has occurred, but if the call is made after a call
to done(), it might be discarded.
done() must be called at the end of synthesis, regardless of errors.
All methods can be only called on the synthesis thread.
Public methods | |
|---|---|
abstract
int
|
audioAvailable(byte[] buffer, int offset, int length)
The service should call this method when synthesized audio is ready for consumption. |
abstract
int
|
done()
The service should call this method when all the synthesized audio for a request has
been passed to |
abstract
void
|
error(int errorCode)
The service should call this method if the speech synthesis fails. |
abstract
void
|
error()
The service should call this method if the speech synthesis fails. |
abstract
int
|
getMaxBufferSize()
|
abstract
boolean
|
hasFinished()
Check if |
abstract
boolean
|
hasStarted()
Check if |
abstract
int
|
start(int sampleRateInHz, int audioFormat, int channelCount)
The service should call this when it starts to synthesize audio for this request. |
Developers
int audioAvailable (byte[] buffer,
int offset,
int length)
The service should call this method when synthesized audio is ready for consumption.
This method should only be called on the synthesis thread,
while in onSynthesizeText(SynthesisRequest, SynthesisCallback).
| Parameters | |
|---|---|
buffer |
byte:
The generated audio data. This method will not hold on to buffer,
so the caller is free to modify it after this method returns. |
offset |
int:
The offset into buffer where the audio data starts. |
length |
int:
The number of bytes of audio data in buffer. This must be
less than or equal to the return value of getMaxBufferSize(). |
| Returns | |
|---|---|
int |
SUCCESS, ERROR or
STOPPED.
|
int done ()
The service should call this method when all the synthesized audio for a request has
been passed to audioAvailable(byte[], int, int).
This method should only be called on the synthesis thread,
while in onSynthesizeText(SynthesisRequest, SynthesisCallback).
This method has to be called if start(int, int, int) and/or error() was called.
| Returns | |
|---|---|
int |
SUCCESS, ERROR or
STOPPED.
|
void error (int errorCode)
The service should call this method if the speech synthesis fails.
This method should only be called on the synthesis thread,
while in onSynthesizeText(SynthesisRequest, SynthesisCallback).
| Parameters | |
|---|---|
errorCode |
int:
Error code to pass to the client. One of the ERROR_ values from
TextToSpeech
|
void error ()
The service should call this method if the speech synthesis fails.
This method should only be called on the synthesis thread,
while in onSynthesizeText(SynthesisRequest, SynthesisCallback).
int getMaxBufferSize ()
| Returns | |
|---|---|
int |
the maximum number of bytes that the TTS engine can pass in a single call of
audioAvailable(byte[], int, int). Calls to audioAvailable(byte[], int, int) with data lengths
larger than this value will not succeed.
|
boolean hasFinished ()
Check if done() was called or not.
This method should only be called on the synthesis thread,
while in onSynthesizeText(SynthesisRequest, SynthesisCallback).
Useful for checking if a fallback from network request is possible.
| Returns | |
|---|---|
boolean |
|
boolean hasStarted ()
Check if start(int, int, int) was called or not.
This method should only be called on the synthesis thread,
while in onSynthesizeText(SynthesisRequest, SynthesisCallback).
Useful for checking if a fallback from network request is possible.
| Returns | |
|---|---|
boolean |
|
int start (int sampleRateInHz,
int audioFormat,
int channelCount)
The service should call this when it starts to synthesize audio for this
request.
This method should only be called on the synthesis thread,
while in onSynthesizeText(SynthesisRequest, SynthesisCallback).
| Parameters | |
|---|---|
sampleRateInHz |
int:
Sample rate in HZ of the generated audio. |
audioFormat |
int:
Audio format of the generated audio. Must be one of
ENCODING_PCM_8BIT or
ENCODING_PCM_16BIT. Can also be
ENCODING_PCM_FLOAT when targetting Android N and
above. |
channelCount |
int:
The number of channels. Must be 1 or 2. |
| Returns | |
|---|---|
int |
SUCCESS, ERROR or
STOPPED.
|