Add SubtitleExtractor which wraps a SubtitleDecoder.
SubtitleExtractor is a component that extracts subtitle data taken from ExtractorInput into samples. Samples are pushed into an ExtractorOutput (usually SampleQueue). As a temporary solution SubtitleExtractor uses SubtitleDecoder to extract Cues from input data. PiperOrigin-RevId: 390319875
This commit is contained in:
apodob
Oliver Woodman
parent
21251e69a6
commit
c5b01b2f7b
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/*
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* Copyright 2021 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.android.exoplayer2.extractor.subtitle;
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import static com.google.android.exoplayer2.util.Assertions.checkState;
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import static com.google.android.exoplayer2.util.Assertions.checkStateNotNull;
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import androidx.annotation.IntDef;
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import androidx.annotation.Nullable;
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import com.google.android.exoplayer2.C;
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import com.google.android.exoplayer2.Format;
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import com.google.android.exoplayer2.ParserException;
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import com.google.android.exoplayer2.extractor.Extractor;
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import com.google.android.exoplayer2.extractor.ExtractorInput;
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import com.google.android.exoplayer2.extractor.ExtractorOutput;
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import com.google.android.exoplayer2.extractor.PositionHolder;
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import com.google.android.exoplayer2.extractor.TrackOutput;
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import com.google.android.exoplayer2.text.Cue;
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import com.google.android.exoplayer2.text.CueEncoder;
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import com.google.android.exoplayer2.text.SubtitleDecoder;
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import com.google.android.exoplayer2.text.SubtitleDecoderException;
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import com.google.android.exoplayer2.text.SubtitleInputBuffer;
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import com.google.android.exoplayer2.text.SubtitleOutputBuffer;
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import com.google.android.exoplayer2.util.ParsableByteArray;
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import com.google.common.primitives.Ints;
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import java.io.IOException;
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import java.io.InterruptedIOException;
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import java.lang.annotation.Retention;
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import java.lang.annotation.RetentionPolicy;
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import java.util.List;
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import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
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/** Generic extractor for extracting subtitles from various subtitle formats. */
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public class SubtitleExtractor implements Extractor {
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@IntDef(
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value = {
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STATE_CREATED,
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STATE_INITIALIZED,
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STATE_READING,
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STATE_DECODING,
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STATE_WRITING,
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STATE_FINISHED
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})
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@Retention(RetentionPolicy.SOURCE)
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private @interface State {}
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/** The extractor has been created. */
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private static final int STATE_CREATED = 0;
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/** The extractor has been initialized. */
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private static final int STATE_INITIALIZED = 1;
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/** The extractor is reading data from the input. */
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private static final int STATE_READING = 2;
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/** The extractor is queueing data for decoding. */
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private static final int STATE_DECODING = 3;
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/** The extractor is writing data to the output. */
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private static final int STATE_WRITING = 4;
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/** The extractor has finished writing. */
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private static final int STATE_FINISHED = 5;
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private static final int DEFAULT_BUFFER_SIZE = 1024;
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private final SubtitleDecoder subtitleDecoder;
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private final CueEncoder cueEncoder;
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private final ParsableByteArray subtitleData;
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private final Format format;
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private @MonotonicNonNull ExtractorOutput extractorOutput;
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private @MonotonicNonNull TrackOutput trackOutput;
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private int bytesRead;
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@State private int state;
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public SubtitleExtractor(SubtitleDecoder subtitleDecoder, Format format) {
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this.subtitleDecoder = subtitleDecoder;
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cueEncoder = new CueEncoder();
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subtitleData = new ParsableByteArray();
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this.format = format;
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state = STATE_CREATED;
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}
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@Override
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public boolean sniff(ExtractorInput input) throws IOException {
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// TODO: Implement sniff() according to the Extractor interface documentation. For now sniff()
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// can safely return true because we plan to use this class in an ExtractorFactory that returns
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// exactly one Extractor implementation.
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return true;
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}
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@Override
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public void init(ExtractorOutput output) {
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checkState(state == STATE_CREATED);
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extractorOutput = output;
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trackOutput = extractorOutput.track(/* id= */ 0, C.TRACK_TYPE_TEXT);
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trackOutput.format(format);
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state = STATE_INITIALIZED;
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}
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@Override
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public int read(ExtractorInput input, PositionHolder seekPosition) throws IOException {
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switch (state) {
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case STATE_INITIALIZED:
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prepareMemory(input);
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state = readFromInput(input) ? STATE_DECODING : STATE_READING;
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return Extractor.RESULT_CONTINUE;
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case STATE_READING:
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state = readFromInput(input) ? STATE_DECODING : STATE_READING;
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return Extractor.RESULT_CONTINUE;
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case STATE_DECODING:
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queueDataToDecoder();
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state = STATE_WRITING;
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return RESULT_CONTINUE;
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case STATE_WRITING:
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writeToOutput();
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state = STATE_FINISHED;
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return Extractor.RESULT_END_OF_INPUT;
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case STATE_FINISHED:
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return Extractor.RESULT_END_OF_INPUT;
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case STATE_CREATED:
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default:
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throw new IllegalStateException();
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}
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}
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@Override
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public void seek(long position, long timeUs) {}
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@Override
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public void release() {
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// TODO: Proper implementation of this method is missing. Implement release() according to the
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// Extractor interface documentation.
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}
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private void prepareMemory(ExtractorInput input) {
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subtitleData.reset(
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input.getLength() != C.LENGTH_UNSET
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? Ints.checkedCast(input.getLength())
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: DEFAULT_BUFFER_SIZE);
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}
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/** Returns whether reading has been finished. */
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private boolean readFromInput(ExtractorInput input) throws IOException {
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if (subtitleData.capacity() == bytesRead) {
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subtitleData.ensureCapacity(bytesRead + DEFAULT_BUFFER_SIZE);
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}
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int readResult =
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input.read(subtitleData.getData(), bytesRead, subtitleData.capacity() - bytesRead);
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if (readResult != C.RESULT_END_OF_INPUT) {
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bytesRead += readResult;
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}
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return readResult == C.RESULT_END_OF_INPUT;
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}
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private void queueDataToDecoder() throws IOException {
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try {
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@Nullable SubtitleInputBuffer inputBuffer = subtitleDecoder.dequeueInputBuffer();
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while (inputBuffer == null) {
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inputBuffer = subtitleDecoder.dequeueInputBuffer();
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Thread.sleep(5);
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}
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inputBuffer.ensureSpaceForWrite(bytesRead);
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inputBuffer.data.put(subtitleData.getData(), /* offset= */ 0, bytesRead);
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subtitleDecoder.queueInputBuffer(inputBuffer);
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} catch (InterruptedException e) {
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Thread.currentThread().interrupt();
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throw new InterruptedIOException();
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} catch (SubtitleDecoderException e) {
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throw ParserException.createForMalformedContainer("SubtitleDecoder failed.", e);
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}
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}
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private void writeToOutput() throws IOException {
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checkStateNotNull(this.trackOutput);
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try {
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@Nullable SubtitleOutputBuffer outputBuffer = subtitleDecoder.dequeueOutputBuffer();
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while (outputBuffer == null) {
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outputBuffer = subtitleDecoder.dequeueOutputBuffer();
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Thread.sleep(5);
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}
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for (int i = 0; i < outputBuffer.getEventTimeCount(); i++) {
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List<Cue> cues = outputBuffer.getCues(outputBuffer.getEventTime(i));
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byte[] cuesSample = cueEncoder.encode(cues);
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trackOutput.sampleData(new ParsableByteArray(cuesSample), cuesSample.length);
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trackOutput.sampleMetadata(
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/* timeUs= */ outputBuffer.getEventTime(i),
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/* flags= */ C.BUFFER_FLAG_KEY_FRAME,
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/* size= */ cuesSample.length,
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/* offset= */ 0,
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/* cryptoData= */ null);
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}
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} catch (InterruptedException e) {
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Thread.currentThread().interrupt();
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throw new InterruptedIOException();
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} catch (SubtitleDecoderException e) {
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throw ParserException.createForMalformedContainer("SubtitleDecoder failed.", e);
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}
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}
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}
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/*
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* Copyright 2021 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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@NonNullApi
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package com.google.android.exoplayer2.extractor.subtitle;
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import com.google.android.exoplayer2.util.NonNullApi;
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/*
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* Copyright 2021 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.android.exoplayer2.extractor.subtitle;
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import static com.google.common.truth.Truth.assertThat;
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import static org.junit.Assert.assertThrows;
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import androidx.test.ext.junit.runners.AndroidJUnit4;
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import com.google.android.exoplayer2.Format;
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import com.google.android.exoplayer2.extractor.Extractor;
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import com.google.android.exoplayer2.testutil.FakeExtractorInput;
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import com.google.android.exoplayer2.testutil.FakeExtractorOutput;
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import com.google.android.exoplayer2.testutil.FakeTrackOutput;
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import com.google.android.exoplayer2.text.Cue;
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import com.google.android.exoplayer2.text.CueDecoder;
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import com.google.android.exoplayer2.text.webvtt.WebvttDecoder;
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import com.google.android.exoplayer2.util.Util;
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import java.util.List;
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import org.junit.Test;
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import org.junit.runner.RunWith;
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/** Tests for {@link SubtitleExtractor}. */
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@RunWith(AndroidJUnit4.class)
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public class SubtitleExtractorTest {
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@Test
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public void extractor_outputsCues() throws Exception {
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String testData =
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"WEBVTT\n"
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+ "\n"
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+ "00:00.000 --> 00:01.234\n"
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+ "This is the first subtitle.\n"
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+ "\n"
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+ "00:02.345 --> 00:03.456\n"
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+ "This is the second subtitle.\n"
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+ "\n"
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+ "00:02.600 --> 00:04.567\n"
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+ "This is the third subtitle.";
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CueDecoder decoder = new CueDecoder();
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FakeExtractorOutput output = new FakeExtractorOutput();
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FakeExtractorInput input =
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new FakeExtractorInput.Builder()
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.setData(Util.getUtf8Bytes(testData))
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.setSimulatePartialReads(true)
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.build();
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SubtitleExtractor extractor =
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new SubtitleExtractor(new WebvttDecoder(), new Format.Builder().build());
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extractor.init(output);
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while (extractor.read(input, null) != Extractor.RESULT_END_OF_INPUT) {}
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FakeTrackOutput trackOutput = output.trackOutputs.get(0);
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assertThat(trackOutput.getSampleCount()).isEqualTo(6);
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// Check sample timestamps.
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assertThat(trackOutput.getSampleTimeUs(0)).isEqualTo(0L);
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assertThat(trackOutput.getSampleTimeUs(1)).isEqualTo(1_234_000L);
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assertThat(trackOutput.getSampleTimeUs(2)).isEqualTo(2_345_000L);
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assertThat(trackOutput.getSampleTimeUs(3)).isEqualTo(2_600_000L);
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assertThat(trackOutput.getSampleTimeUs(4)).isEqualTo(3_456_000L);
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assertThat(trackOutput.getSampleTimeUs(5)).isEqualTo(4_567_000L);
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// Check sample content.
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List<Cue> cues0 = decoder.decode(trackOutput.getSampleData(0));
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assertThat(cues0).hasSize(1);
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assertThat(cues0.get(0).text.toString()).isEqualTo("This is the first subtitle.");
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List<Cue> cues1 = decoder.decode(trackOutput.getSampleData(1));
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assertThat(cues1).isEmpty();
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List<Cue> cues2 = decoder.decode(trackOutput.getSampleData(2));
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assertThat(cues2).hasSize(1);
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assertThat(cues2.get(0).text.toString()).isEqualTo("This is the second subtitle.");
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List<Cue> cues3 = decoder.decode(trackOutput.getSampleData(3));
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assertThat(cues3).hasSize(2);
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assertThat(cues3.get(0).text.toString()).isEqualTo("This is the second subtitle.");
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assertThat(cues3.get(1).text.toString()).isEqualTo("This is the third subtitle.");
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List<Cue> cues4 = decoder.decode(trackOutput.getSampleData(4));
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assertThat(cues4).hasSize(1);
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assertThat(cues4.get(0).text.toString()).isEqualTo("This is the third subtitle.");
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List<Cue> cues5 = decoder.decode(trackOutput.getSampleData(5));
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assertThat(cues5).isEmpty();
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}
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@Test
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public void read_notInitialized_fails() {
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FakeExtractorInput input = new FakeExtractorInput.Builder().setData(new byte[0]).build();
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SubtitleExtractor extractor =
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new SubtitleExtractor(new WebvttDecoder(), new Format.Builder().build());
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assertThrows(IllegalStateException.class, () -> extractor.read(input, null));
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}
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}
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