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/*
* Copyright (C) 2016 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 org.mozilla.thirdparty.com.google.android.exoplayer2.trackselection;
import android.os.SystemClock;
import androidx.annotation.Nullable;
import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
import org.mozilla.thirdparty.com.google.android.exoplayer2.source.TrackGroup;
import org.mozilla.thirdparty.com.google.android.exoplayer2.source.chunk.MediaChunk;
import org.mozilla.thirdparty.com.google.android.exoplayer2.source.chunk.MediaChunkIterator;
import org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.BandwidthMeter;
import java.util.List;
import java.util.Random;
import org.checkerframework.checker.nullness.compatqual.NullableType;
/**
* A {@link TrackSelection} whose selected track is updated randomly.
*/
public final class RandomTrackSelection extends BaseTrackSelection {
/**
* Factory for {@link RandomTrackSelection} instances.
*/
public static final class Factory implements TrackSelection.Factory {
private final Random random;
public Factory() {
random = new Random();
}
/**
* @param seed A seed for the {@link Random} instance used by the factory.
*/
public Factory(int seed) {
random = new Random(seed);
}
@Override
public @NullableType TrackSelection[] createTrackSelections(
@NullableType Definition[] definitions, BandwidthMeter bandwidthMeter) {
return TrackSelectionUtil.createTrackSelectionsForDefinitions(
definitions,
definition -> new RandomTrackSelection(definition.group, definition.tracks, random));
}
}
private final Random random;
private int selectedIndex;
/**
* @param group The {@link TrackGroup}. Must not be null.
* @param tracks The indices of the selected tracks within the {@link TrackGroup}. Must not be
* null or empty. May be in any order.
*/
public RandomTrackSelection(TrackGroup group, int... tracks) {
super(group, tracks);
random = new Random();
selectedIndex = random.nextInt(length);
}
/**
* @param group The {@link TrackGroup}. Must not be null.
* @param tracks The indices of the selected tracks within the {@link TrackGroup}. Must not be
* null or empty. May be in any order.
* @param seed A seed for the {@link Random} instance used to update the selected track.
*/
public RandomTrackSelection(TrackGroup group, int[] tracks, long seed) {
this(group, tracks, new Random(seed));
}
/**
* @param group The {@link TrackGroup}. Must not be null.
* @param tracks The indices of the selected tracks within the {@link TrackGroup}. Must not be
* null or empty. May be in any order.
* @param random A source of random numbers.
*/
public RandomTrackSelection(TrackGroup group, int[] tracks, Random random) {
super(group, tracks);
this.random = random;
selectedIndex = random.nextInt(length);
}
@Override
public void updateSelectedTrack(
long playbackPositionUs,
long bufferedDurationUs,
long availableDurationUs,
List<? extends MediaChunk> queue,
MediaChunkIterator[] mediaChunkIterators) {
// Count the number of non-blacklisted formats.
long nowMs = SystemClock.elapsedRealtime();
int nonBlacklistedFormatCount = 0;
for (int i = 0; i < length; i++) {
if (!isBlacklisted(i, nowMs)) {
nonBlacklistedFormatCount++;
}
}
selectedIndex = random.nextInt(nonBlacklistedFormatCount);
if (nonBlacklistedFormatCount != length) {
// Adjust the format index to account for blacklisted formats.
nonBlacklistedFormatCount = 0;
for (int i = 0; i < length; i++) {
if (!isBlacklisted(i, nowMs) && selectedIndex == nonBlacklistedFormatCount++) {
selectedIndex = i;
return;
}
}
}
}
@Override
public int getSelectedIndex() {
return selectedIndex;
}
@Override
public int getSelectionReason() {
return C.SELECTION_REASON_ADAPTIVE;
}
@Override
@Nullable
public Object getSelectionData() {
return null;
}
}
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