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AudioStreamPublisher.java

BidirectionalStreaming.java demonstrates how to use the AWS Transcribe service to transcribe an audio input.

/* Copyright 2010-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved. This file is licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance with the License. A copy of the License is located at http://aws.amazon.com/apache2.0/ This file 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 com.amazonaws.transcribe; import java.io.IOException; import java.io.InputStream; import java.io.UncheckedIOException; import java.nio.ByteBuffer; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.atomic.AtomicLong; import org.reactivestreams.Publisher; import org.reactivestreams.Subscriber; import org.reactivestreams.Subscription; import software.amazon.awssdk.core.SdkBytes; import software.amazon.awssdk.services.transcribestreaming.model.AudioEvent; import software.amazon.awssdk.services.transcribestreaming.model.AudioStream; public class AudioStreamPublisher implements Publisher<AudioStream> { private final InputStream inputStream; public AudioStreamPublisher(InputStream inputStream) { this.inputStream = inputStream; } @Override public void subscribe(Subscriber<? super AudioStream> s) { s.onSubscribe(new SubscriptionImpl(s, inputStream)); } private class SubscriptionImpl implements Subscription { private static final int CHUNK_SIZE_IN_BYTES = 1024 * 1; private ExecutorService executor = Executors.newFixedThreadPool(1); private AtomicLong demand = new AtomicLong(0); private final Subscriber<? super AudioStream> subscriber; private final InputStream inputStream; private SubscriptionImpl(Subscriber<? super AudioStream> s, InputStream inputStream) { this.subscriber = s; this.inputStream = inputStream; } @Override public void request(long n) { if (n <= 0) { subscriber.onError(new IllegalArgumentException("Demand must be positive")); } demand.getAndAdd(n); executor.submit(() -> { try { do { ByteBuffer audioBuffer = getNextEvent(); if (audioBuffer.remaining() > 0) { AudioEvent audioEvent = audioEventFromBuffer(audioBuffer); subscriber.onNext(audioEvent); } else { subscriber.onComplete(); break; } } while (demand.decrementAndGet() > 0); } catch (Exception e) { subscriber.onError(e); } }); } @Override public void cancel() { } private ByteBuffer getNextEvent() { ByteBuffer audioBuffer; byte[] audioBytes = new byte[CHUNK_SIZE_IN_BYTES]; int len = 0; try { len = inputStream.read(audioBytes); if (len <= 0) { audioBuffer = ByteBuffer.allocate(0); } else { audioBuffer = ByteBuffer.wrap(audioBytes, 0, len); } } catch (IOException e) { throw new UncheckedIOException(e); } return audioBuffer; } private AudioEvent audioEventFromBuffer(ByteBuffer bb) { return AudioEvent.builder() .audioChunk(SdkBytes.fromByteBuffer(bb)) .build(); } } }

Sample Details

Service: transcribe

Last tested: 2019-04-18

Author: AWS

Type: full-example

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