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/*
* Copyright (C) 2015 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 com.android.tv.tuner.exoplayer;
import android.os.Handler;
import com.google.android.exoplayer.MediaFormat;
import com.google.android.exoplayer.MediaFormatHolder;
import com.google.android.exoplayer.SampleHolder;
import com.google.android.exoplayer.SampleSource;
import com.google.android.exoplayer.TrackRenderer;
import java.io.IOException;
import java.util.List;
/**
* Extractor for reading track metadata and samples stored in tracks.
*
* <p>Call {@link #prepare} until it returns {@code true}, then access track metadata via
* {@link #getTrackFormats} and {@link #getTrackMediaFormat}.
*
* <p>Pass indices of tracks to read from to {@link #selectTrack}. A track can later be deselected
* by calling {@link #deselectTrack}. It is safe to select/deselect tracks after reading sample
* data or seeking. Initially, all tracks are deselected.
*
* <p>Call {@link #release()} when the extractor is no longer needed to free resources.
*/
public interface SampleExtractor {
/**
* If the extractor is currently having difficulty preparing or loading samples, then this
* method throws the underlying error. Otherwise does nothing.
*
* @throws IOException The underlying error.
*/
void maybeThrowError() throws IOException;
/**
* Prepares the extractor for reading track metadata and samples.
*
* @return whether the source is ready; if {@code false}, this method must be called again.
* @throws IOException thrown if the source can't be read
*/
boolean prepare() throws IOException;
/** Returns track information about all tracks that can be selected. */
List<MediaFormat> getTrackFormats();
/** Selects the track at {@code index} for reading sample data. */
void selectTrack(int index);
/** Deselects the track at {@code index}, so no more samples will be read from that track. */
void deselectTrack(int index);
/**
* Returns an estimate of the position up to which data is buffered.
*
* <p>This method should not be called until after the extractor has been successfully prepared.
*
* @return an estimate of the absolute position in microseconds up to which data is buffered,
* or {@link TrackRenderer#END_OF_TRACK_US} if data is buffered to the end of the stream, or
* {@link TrackRenderer#UNKNOWN_TIME_US} if no estimate is available.
*/
long getBufferedPositionUs();
/**
* Seeks to the specified time in microseconds.
*
* <p>This method should not be called until after the extractor has been successfully prepared.
*
* @param positionUs the seek position in microseconds
*/
void seekTo(long positionUs);
/** Stores the {@link MediaFormat} of {@code track}. */
void getTrackMediaFormat(int track, MediaFormatHolder outMediaFormatHolder);
/**
* Reads the next sample in the track at index {@code track} into {@code sampleHolder}, returning
* {@link SampleSource#SAMPLE_READ} if it is available.
*
* <p>Advances to the next sample if a sample was read.
*
* @param track the index of the track from which to read a sample
* @param sampleHolder the holder for read sample data, if {@link SampleSource#SAMPLE_READ} is
* returned
* @return {@link SampleSource#SAMPLE_READ} if a sample was read into {@code sampleHolder}, or
* {@link SampleSource#END_OF_STREAM} if the last samples in all tracks have been read, or
* {@link SampleSource#NOTHING_READ} if the sample cannot be read immediately as it is not
* loaded.
*/
int readSample(int track, SampleHolder sampleHolder);
/** Releases resources associated with this extractor. */
void release();
/** Indicates to the source that it should still be buffering data. */
boolean continueBuffering(long positionUs);
/**
* Sets OnCompletionListener for notifying the completion of SampleExtractor.
*
* @param listener the OnCompletionListener
* @param handler the {@link Handler} for {@link Handler#post(Runnable)} of OnCompletionListener
*/
void setOnCompletionListener(OnCompletionListener listener, Handler handler);
/**
* The listener for SampleExtractor being completed.
*/
interface OnCompletionListener {
/**
* Called when sample extraction is completed.
*
* @param result {@code true} when the extractor is finished without an error,
* {@code false} otherwise (storage error, weak signal, being reached at EoS
* prematurely, etc.)
* @param lastExtractedPositionUs the last extracted position when extractor is completed
*/
void onCompletion(boolean result, long lastExtractedPositionUs);
}
}
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