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/* * Copyright (C) 2011 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. */ package android.speech.tts; import android.annotation.IntDef; import android.annotation.IntRange; import android.media.AudioFormat; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; /** * A callback to return speech data synthesized by a text to speech engine. * * The engine can provide streaming audio by calling * {@link #start}, then {@link #audioAvailable} until all audio has been provided, then finally * {@link #done}. * * {@link #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 {@link #done}, it might be discarded. * * {@link #done} must be called at the end of synthesis, regardless of errors. * * All methods can be only called on the synthesis thread. */ public interface SynthesisCallback { /** @hide */ @Retention(RetentionPolicy.SOURCE) @IntDef({ AudioFormat.ENCODING_PCM_8BIT, AudioFormat.ENCODING_PCM_16BIT, AudioFormat.ENCODING_PCM_FLOAT }) @interface SupportedAudioFormat { }; /** * @return the maximum number of bytes that the TTS engine can pass in a single call of {@link * #audioAvailable}. Calls to {@link #audioAvailable} with data lengths larger than this * value will not succeed. */ int getMaxBufferSize(); /** * The service should call this when it starts to synthesize audio for this request. * * <p>This method should only be called on the synthesis thread, while in {@link * TextToSpeechService#onSynthesizeText}. * * @param sampleRateInHz Sample rate in HZ of the generated audio. * @param audioFormat Audio format of the generated audio. Must be one of {@link * AudioFormat#ENCODING_PCM_8BIT} or {@link AudioFormat#ENCODING_PCM_16BIT}. Can also be * {@link AudioFormat#ENCODING_PCM_FLOAT} when targetting Android N and above. * @param channelCount The number of channels. Must be {@code 1} or {@code 2}. * @return {@link android.speech.tts.TextToSpeech#SUCCESS}, {@link * android.speech.tts.TextToSpeech#ERROR} or {@link android.speech.tts.TextToSpeech#STOPPED}. */ int start(int sampleRateInHz, @SupportedAudioFormat int audioFormat, @IntRange(from = 1, to = 2) int channelCount); /** * The service should call this method when synthesized audio is ready for consumption. * * <p>This method should only be called on the synthesis thread, while in {@link * TextToSpeechService#onSynthesizeText}. * * @param buffer The generated audio data. This method will not hold on to {@code buffer}, so the * caller is free to modify it after this method returns. * @param offset The offset into {@code buffer} where the audio data starts. * @param length The number of bytes of audio data in {@code buffer}. This must be less than or * equal to the return value of {@link #getMaxBufferSize}. * @return {@link android.speech.tts.TextToSpeech#SUCCESS}, {@link * android.speech.tts.TextToSpeech#ERROR} or {@link android.speech.tts.TextToSpeech#STOPPED}. */ int audioAvailable(byte[] buffer, int offset, int length); /** * The service should call this method when all the synthesized audio for a request has been * passed to {@link #audioAvailable}. * * <p>This method should only be called on the synthesis thread, while in {@link * TextToSpeechService#onSynthesizeText}. * * <p>This method has to be called if {@link #start} and/or {@link #error} was called. * * @return {@link android.speech.tts.TextToSpeech#SUCCESS}, {@link * android.speech.tts.TextToSpeech#ERROR} or {@link android.speech.tts.TextToSpeech#STOPPED}. */ int done(); /** * The service should call this method if the speech synthesis fails. * * <p>This method should only be called on the synthesis thread, while in {@link * TextToSpeechService#onSynthesizeText}. */ void error(); /** * The service should call this method if the speech synthesis fails. * * <p>This method should only be called on the synthesis thread, while in {@link * TextToSpeechService#onSynthesizeText}. * * @param errorCode Error code to pass to the client. One of the ERROR_ values from {@link * android.speech.tts.TextToSpeech} */ void error(@TextToSpeech.Error int errorCode); /** * Check if {@link #start} was called or not. * * <p>This method should only be called on the synthesis thread, while in {@link * TextToSpeechService#onSynthesizeText}. * * <p>Useful for checking if a fallback from network request is possible. */ boolean hasStarted(); /** * Check if {@link #done} was called or not. * * <p>This method should only be called on the synthesis thread, while in {@link * TextToSpeechService#onSynthesizeText}. * * <p>Useful for checking if a fallback from network request is possible. */ boolean hasFinished(); /** * The service may call this method to provide timing information about the spoken text. * * <p>Calling this method means that at the given audio frame, the given range of the input is * about to be spoken. If this method is called the client will receive a callback on the * listener ({@link UtteranceProgressListener#onRangeStart}) at the moment that frame has been * reached by the playback head. * * <p>This information can be used by the client, for example, to highlight ranges of the text * while it is spoken. * * <p>The markerInFrames is a frame index into the audio for this synthesis request, i.e. into * the concatenation of the audio bytes sent to audioAvailable for this synthesis request. The * definition of a frame depends on the format given by {@link #start}. See {@link AudioFormat} * for more information. * * <p>This method should only be called on the synthesis thread, while in {@link * TextToSpeechService#onSynthesizeText}. * * @param markerInFrames The position in frames in the audio where this range is spoken. * @param start The start index of the range in the input text. * @param end The end index (exclusive) of the range in the input text. */ default void rangeStart(int markerInFrames, int start, int end) { } }