UtteranceProgressListener

onAudioAvailable

open fun onAudioAvailable(
    utteranceId: String!, 
    audio: ByteArray!
): Unit

This is called when a chunk of audio is ready for consumption.

The audio parameter is a copy of what will be synthesized to the speakers (when synthesis was initiated with a android.speech.tts.TextToSpeech#speak call) or written to the file system (for android.speech.tts.TextToSpeech#synthesizeToFile). The audio bytes are delivered in one or more chunks; if onDone or #onError is called all chunks have been received.

The audio received here may not be played for some time depending on buffer sizes and the amount of items on the synthesis queue.

onBeginSynthesis

open fun onBeginSynthesis(
    utteranceId: String!, 
    sampleRateInHz: Int, 
    audioFormat: Int, 
    channelCount: Int
): Unit

Called when the TTS engine begins to synthesize the audio for a request.

It provides information about the format of the byte array for subsequent onAudioAvailable calls.

This is called when the TTS engine starts synthesizing audio for the request. If an application wishes to know when the audio is about to start playing, {#onStart(String)} should be used instead.

onDone

abstract fun onDone(utteranceId: String!): Unit

Called when an utterance has successfully completed processing. All audio will have been played back by this point for audible output, and all output will have been written to disk for file synthesis requests. This request is guaranteed to be called after onStart(java.lang.String).

onError

abstract fun onError(utteranceId: String!): Unit

Deprecated: Use onError(java.lang.String,int) instead

Called when an error has occurred during processing. This can be called at any point in the synthesis process. Note that there might be calls to onStart(java.lang.String) for specified utteranceId but there will never be a call to both onDone(java.lang.String) and onError(java.lang.String) for the same utterance.

onError

open fun onError(
    utteranceId: String!, 
    errorCode: Int
): Unit

Called when an error has occurred during processing. This can be called at any point in the synthesis process. Note that there might be calls to onStart(java.lang.String) for specified utteranceId but there will never be a call to both onDone(java.lang.String) and onError(java.lang.String,int) for the same utterance. The default implementation calls onError(java.lang.String).

onRangeStart

open fun onRangeStart(
    utteranceId: String!, 
    start: Int, 
    end: Int, 
    frame: Int
): Unit

This is called when the TTS service is about to speak the specified range of the utterance with the given utteranceId.

This method is called when the audio is expected to start playing on the speaker. Note that this is different from onAudioAvailable which is called as soon as the audio is generated.

This information can be used, for example, to highlight ranges of the text while it is spoken.

Only called if the engine supplies timing information by calling android.speech.tts.SynthesisCallback#rangeStart(int,int,int).

onStart

abstract fun onStart(utteranceId: String!): Unit

Called when an utterance "starts" as perceived by the caller. This will be soon before audio is played back in the case of a android.speech.tts.TextToSpeech#speak or before the first bytes of a file are written to the file system in the case of android.speech.tts.TextToSpeech#synthesizeToFile.

onStop

open fun onStop(
    utteranceId: String!, 
    interrupted: Boolean
): Unit

Called when an utterance has been stopped while in progress or flushed from the synthesis queue. This can happen if a client calls TextToSpeech#stop() or uses TextToSpeech#QUEUE_FLUSH as an argument with the android.speech.tts.TextToSpeech#speak or android.speech.tts.TextToSpeech#synthesizeToFile methods.