/*
* Copyright 2023 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
*
* https://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 androidx.media3.extractor.text;
import androidx.media3.common.C;
import androidx.media3.common.Format;
import androidx.media3.common.MimeTypes;
import androidx.media3.common.util.UnstableApi;
import androidx.media3.extractor.Extractor;
import androidx.media3.extractor.ExtractorInput;
import androidx.media3.extractor.ExtractorOutput;
import androidx.media3.extractor.PositionHolder;
import androidx.media3.extractor.TrackOutput;
import java.io.IOException;
import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
/**
* A wrapping {@link Extractor} that transcodes {@linkplain C#TRACK_TYPE_TEXT text samples} from
* supported subtitle formats to {@link MimeTypes#APPLICATION_MEDIA3_CUES}.
*
* <p>Samples emitted by the delegate {@link Extractor} to {@linkplain C#TRACK_TYPE_TEXT text
* tracks} with a supported subtitle format are transcoded and the resulting {@link
* MimeTypes#APPLICATION_MEDIA3_CUES} samples are emitted to the underlying {@link TrackOutput}.
*
* <p>Samples emitted by the delegate {@link Extractor} to non-text tracks (or text tracks with an
* unsupported format) are passed through to the underlying {@link TrackOutput} without
* modification.
*
* <p>Support for subtitle formats is determined by {@link
* SubtitleParser.Factory#supportsFormat(Format)} on the {@link SubtitleParser.Factory} passed to
* the constructor of this class.
*/
@UnstableApi
public class SubtitleTranscodingExtractor implements Extractor {
private final Extractor delegate;
private final SubtitleParser.Factory subtitleParserFactory;
private @MonotonicNonNull SubtitleTranscodingExtractorOutput transcodingExtractorOutput;
public SubtitleTranscodingExtractor(
Extractor delegate, SubtitleParser.Factory subtitleParserFactory) {
this.delegate = delegate;
this.subtitleParserFactory = subtitleParserFactory;
}
@Override
public boolean sniff(ExtractorInput input) throws IOException {
return delegate.sniff(input);
}
@Override
public void init(ExtractorOutput output) {
transcodingExtractorOutput =
new SubtitleTranscodingExtractorOutput(output, subtitleParserFactory);
delegate.init(transcodingExtractorOutput);
}
@Override
public @ReadResult int read(ExtractorInput input, PositionHolder seekPosition)
throws IOException {
return delegate.read(input, seekPosition);
}
@Override
public void seek(long position, long timeUs) {
if (transcodingExtractorOutput != null) {
transcodingExtractorOutput.resetSubtitleParsers();
}
delegate.seek(position, timeUs);
}
@Override
public void release() {
delegate.release();
}
@Override
public Extractor getUnderlyingImplementation() {
return delegate;
}
}