Merge remote-tracking branch 'origin/dev' into dev

app/build.gradle

@@ -8,8 +8,8 @@ android {
         applicationId "org.schabi.newpipe"
         minSdkVersion 15
         targetSdkVersion 27
-        versionCode 60
+        versionCode 61
-        versionName "0.13.1"
+        versionName "0.13.2"
 
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
         vectorDrawables.useSupportLibrary = true
@@ -42,7 +42,7 @@ android {
 
 ext {
     supportLibVersion = '27.1.0'
-    exoPlayerLibVersion = '2.7.1'
+    exoPlayerLibVersion = '2.7.3'
     roomDbLibVersion = '1.0.0'
     leakCanaryLibVersion = '1.5.4'
     okHttpLibVersion = '1.5.0'
@@ -73,6 +73,7 @@ dependencies {
     implementation 'de.hdodenhof:circleimageview:2.2.0'
     implementation 'com.github.nirhart:ParallaxScroll:dd53d1f9d1'
     implementation 'com.nononsenseapps:filepicker:4.2.1'
+
     implementation "com.google.android.exoplayer:exoplayer:$exoPlayerLibVersion"
     implementation "com.google.android.exoplayer:extension-mediasession:$exoPlayerLibVersion"
 

app/src/main/AndroidManifest.xml

@@ -42,7 +42,11 @@
 
         <service
             android:name=".player.BackgroundPlayer"
-            android:exported="false"/>
+            android:exported="false">
+            <intent-filter>
+                <action android:name="android.intent.action.MEDIA_BUTTON" />
+            </intent-filter>
+        </service>
 
         <activity
             android:name=".player.BackgroundPlayerActivity"

app/src/main/java/org/schabi/newpipe/fragments/detail/VideoDetailFragment.java

@@ -87,6 +87,7 @@ import org.schabi.newpipe.util.ThemeHelper;
 
 import java.io.Serializable;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
 
@@ -538,7 +539,8 @@ public class VideoDetailFragment
 
         final String[] commands = new String[]{
                 context.getResources().getString(R.string.enqueue_on_background),
-                context.getResources().getString(R.string.enqueue_on_popup)
+                context.getResources().getString(R.string.enqueue_on_popup),
+                context.getResources().getString(R.string.append_playlist)
         };
 
         final DialogInterface.OnClickListener actions = (DialogInterface dialogInterface, int i) -> {
@@ -549,6 +551,12 @@ public class VideoDetailFragment
                 case 1:
                     NavigationHelper.enqueueOnPopupPlayer(getActivity(), new SinglePlayQueue(item));
                     break;
+                case 2:
+                    if (getFragmentManager() != null) {
+                        PlaylistAppendDialog.fromStreamInfoItems(Collections.singletonList(item))
+                                .show(getFragmentManager(), TAG);
+                    }
+                    break;
                 default:
                     break;
             }

app/src/main/java/org/schabi/newpipe/fragments/list/channel/ChannelFragment.java

@@ -36,6 +36,7 @@ import org.schabi.newpipe.extractor.stream.Stream;
 import org.schabi.newpipe.extractor.stream.StreamInfo;
 import org.schabi.newpipe.extractor.stream.StreamInfoItem;
 import org.schabi.newpipe.fragments.list.BaseListInfoFragment;
+import org.schabi.newpipe.fragments.local.dialog.PlaylistAppendDialog;
 import org.schabi.newpipe.info_list.InfoItemDialog;
 import org.schabi.newpipe.playlist.ChannelPlayQueue;
 import org.schabi.newpipe.playlist.PlayQueue;
@@ -49,6 +50,7 @@ import org.schabi.newpipe.util.Localization;
 import org.schabi.newpipe.util.NavigationHelper;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.TimeUnit;
 
@@ -161,6 +163,7 @@ public class ChannelFragment extends BaseListInfoFragment<ChannelInfo> {
                 context.getResources().getString(R.string.start_here_on_main),
                 context.getResources().getString(R.string.start_here_on_background),
                 context.getResources().getString(R.string.start_here_on_popup),
+                context.getResources().getString(R.string.append_playlist)
         };
 
         final DialogInterface.OnClickListener actions = new DialogInterface.OnClickListener() {
@@ -183,6 +186,12 @@ public class ChannelFragment extends BaseListInfoFragment<ChannelInfo> {
                     case 4:
                         NavigationHelper.playOnPopupPlayer(activity, getPlayQueue(index));
                         break;
+                    case 5:
+                        if (getFragmentManager() != null) {
+                            PlaylistAppendDialog.fromStreamInfoItems(Collections.singletonList(item))
+                                    .show(getFragmentManager(), TAG);
+                        }
+                        break;
                     default:
                         break;
                 }

app/src/main/java/org/schabi/newpipe/fragments/local/bookmark/BookmarkFragment.java

@@ -56,7 +56,8 @@ public final class BookmarkFragment
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        final AppDatabase database = NewPipeDatabase.getInstance(getContext());
+        if (activity == null) return;
+        final AppDatabase database = NewPipeDatabase.getInstance(activity);
         localPlaylistManager = new LocalPlaylistManager(database);
         remotePlaylistManager = new RemotePlaylistManager(database);
         disposables = new CompositeDisposable();

app/src/main/java/org/schabi/newpipe/player/BackgroundPlayer.java

@@ -118,8 +118,12 @@ public final class BackgroundPlayer extends Service {
 
     @Override
     public int onStartCommand(Intent intent, int flags, int startId) {
-        if (DEBUG) Log.d(TAG, "onStartCommand() called with: intent = [" + intent + "], flags = [" + flags + "], startId = [" + startId + "]");
+        if (DEBUG) Log.d(TAG, "onStartCommand() called with: intent = [" + intent +
+                "], flags = [" + flags + "], startId = [" + startId + "]");
         basePlayerImpl.handleIntent(intent);
+        if (basePlayerImpl.mediaSessionManager != null) {
+            basePlayerImpl.mediaSessionManager.handleMediaButtonIntent(intent);
+        }
         return START_NOT_STICKY;
     }
 
@@ -160,6 +164,11 @@ public final class BackgroundPlayer extends Service {
         if (DEBUG) Log.d(TAG, "onScreenOnOff() called with: on = [" + on + "]");
         shouldUpdateOnProgress = on;
         basePlayerImpl.triggerProgressUpdate();
+        if (on) {
+            basePlayerImpl.startProgressLoop();
+        } else {
+            basePlayerImpl.stopProgressLoop();
+        }
     }
 
     /*//////////////////////////////////////////////////////////////////////////
@@ -545,7 +554,6 @@ public final class BackgroundPlayer extends Service {
             super.onPaused();
 
             updateNotification(R.drawable.ic_play_arrow_white);
-            if (isProgressLoopRunning()) stopProgressLoop();
 
             lockManager.releaseWifiAndCpu();
         }

app/src/main/java/org/schabi/newpipe/player/BasePlayer.java

@@ -46,7 +46,7 @@ import com.google.android.exoplayer2.Timeline;
 import com.google.android.exoplayer2.source.BehindLiveWindowException;
 import com.google.android.exoplayer2.source.MediaSource;
 import com.google.android.exoplayer2.source.TrackGroupArray;
-import com.google.android.exoplayer2.trackselection.AdaptiveTrackSelection;
+import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.trackselection.TrackSelectionArray;
 import com.google.android.exoplayer2.upstream.DefaultBandwidthMeter;
 import com.google.android.exoplayer2.util.Util;
@@ -64,6 +64,7 @@ import org.schabi.newpipe.player.helper.LoadController;
 import org.schabi.newpipe.player.helper.MediaSessionManager;
 import org.schabi.newpipe.player.helper.PlayerDataSource;
 import org.schabi.newpipe.player.helper.PlayerHelper;
+import org.schabi.newpipe.player.mediasource.FailedMediaSource;
 import org.schabi.newpipe.player.playback.BasePlayerMediaSession;
 import org.schabi.newpipe.player.playback.CustomTrackSelector;
 import org.schabi.newpipe.player.playback.MediaSourceManager;
@@ -124,7 +125,6 @@ public abstract class BasePlayer implements
     //////////////////////////////////////////////////////////////////////////*/
 
     protected static final float[] PLAYBACK_SPEEDS = {0.5f, 0.75f, 1f, 1.25f, 1.5f, 1.75f, 2f};
-    protected static final float[] PLAYBACK_PITCHES = {0.8f, 0.9f, 0.95f, 1f, 1.05f, 1.1f, 1.2f};
 
     protected PlayQueue playQueue;
     protected PlayQueueAdapter playQueueAdapter;
@@ -140,10 +140,10 @@ public abstract class BasePlayer implements
     // Player
     //////////////////////////////////////////////////////////////////////////*/
 
-    protected final static int FAST_FORWARD_REWIND_AMOUNT = 10000; // 10 Seconds
+    protected final static int FAST_FORWARD_REWIND_AMOUNT_MILLIS = 10000; // 10 Seconds
-    protected final static int PLAY_PREV_ACTIVATION_LIMIT = 5000; // 5 seconds
+    protected final static int PLAY_PREV_ACTIVATION_LIMIT_MILLIS = 5000; // 5 seconds
-    protected final static int PROGRESS_LOOP_INTERVAL = 500;
+    protected final static int PROGRESS_LOOP_INTERVAL_MILLIS = 500;
-    protected final static int RECOVERY_SKIP_THRESHOLD = 3000; // 3 seconds
+    protected final static int RECOVERY_SKIP_THRESHOLD_MILLIS = 3000; // 3 seconds
 
     protected CustomTrackSelector trackSelector;
     protected PlayerDataSource dataSource;
@@ -177,11 +177,11 @@ public abstract class BasePlayer implements
     }
 
     public void setup() {
-        if (simpleExoPlayer == null) initPlayer();
+        if (simpleExoPlayer == null) initPlayer(/*playOnInit=*/true);
         initListeners();
     }
 
-    public void initPlayer() {
+    public void initPlayer(final boolean playOnReady) {
         if (DEBUG) Log.d(TAG, "initPlayer() called with: context = [" + context + "]");
 
         if (databaseUpdateReactor != null) databaseUpdateReactor.dispose();
@@ -191,15 +191,15 @@ public abstract class BasePlayer implements
         final DefaultBandwidthMeter bandwidthMeter = new DefaultBandwidthMeter();
         dataSource = new PlayerDataSource(context, userAgent, bandwidthMeter);
 
-        final AdaptiveTrackSelection.Factory trackSelectionFactory =
+        final TrackSelection.Factory trackSelectionFactory =
-                new AdaptiveTrackSelection.Factory(bandwidthMeter);
+                PlayerHelper.getQualitySelector(context, bandwidthMeter);
         trackSelector = new CustomTrackSelector(trackSelectionFactory);
 
         final LoadControl loadControl = new LoadController(context);
         final RenderersFactory renderFactory = new DefaultRenderersFactory(context);
         simpleExoPlayer = ExoPlayerFactory.newSimpleInstance(renderFactory, trackSelector, loadControl);
         simpleExoPlayer.addListener(this);
-        simpleExoPlayer.setPlayWhenReady(true);
+        simpleExoPlayer.setPlayWhenReady(playOnReady);
         simpleExoPlayer.setSeekParameters(PlayerHelper.getSeekParameters(context));
 
         audioReactor = new AudioReactor(context, simpleExoPlayer);
@@ -237,15 +237,16 @@ public abstract class BasePlayer implements
         final float playbackPitch = intent.getFloatExtra(PLAYBACK_PITCH, getPlaybackPitch());
 
         // Good to go...
-        initPlayback(queue, repeatMode, playbackSpeed, playbackPitch);
+        initPlayback(queue, repeatMode, playbackSpeed, playbackPitch, /*playOnInit=*/true);
     }
 
     protected void initPlayback(@NonNull final PlayQueue queue,
                                 @Player.RepeatMode final int repeatMode,
                                 final float playbackSpeed,
-                                final float playbackPitch) {
+                                final float playbackPitch,
+                                final boolean playOnReady) {
         destroyPlayer();
-        initPlayer();
+        initPlayer(playOnReady);
         setRepeatMode(repeatMode);
         setPlaybackParameters(playbackSpeed, playbackPitch);
 
@@ -518,15 +519,16 @@ public abstract class BasePlayer implements
     }
 
     public void triggerProgressUpdate() {
+        if (simpleExoPlayer == null) return;
         onUpdateProgress(
-                (int) simpleExoPlayer.getCurrentPosition(),
+                Math.max((int) simpleExoPlayer.getCurrentPosition(), 0),
                 (int) simpleExoPlayer.getDuration(),
                 simpleExoPlayer.getBufferedPercentage()
         );
     }
 
     private Disposable getProgressReactor() {
-        return Observable.interval(PROGRESS_LOOP_INTERVAL, TimeUnit.MILLISECONDS)
+        return Observable.interval(PROGRESS_LOOP_INTERVAL_MILLIS, TimeUnit.MILLISECONDS)
                 .observeOn(AndroidSchedulers.mainThread())
                 .subscribe(ignored -> triggerProgressUpdate());
     }
@@ -553,8 +555,8 @@ public abstract class BasePlayer implements
                 // Ensure dynamic/livestream timeline changes does not cause negative position
                 if (isPlaylistStable && !isCurrentWindowValid() && !isSynchronizing) {
                     if (DEBUG) Log.d(TAG, "Playback - negative time position reached, " +
-                            "clamping position to 0ms.");
+                            "clamping to default position.");
-                    seekTo(/*clampToTime=*/0);
+                    seekToDefault();
                 }
                 break;
         }
@@ -640,12 +642,12 @@ public abstract class BasePlayer implements
             seekTo(recoveryPositionMillis);
             playQueue.unsetRecovery(currentSourceIndex);
 
-        } else if (isSynchronizing && simpleExoPlayer.isCurrentWindowDynamic()) {
+        } else if (isSynchronizing && isLive()) {
             if (DEBUG) Log.d(TAG, "Playback - Synchronizing livestream to default time");
             // Is still synchronizing?
             seekToDefault();
 
-        } else if (isSynchronizing && presetStartPositionMillis != 0L) {
+        } else if (isSynchronizing && presetStartPositionMillis > 0L) {
             if (DEBUG) Log.d(TAG, "Playback - Seeking to preset start " +
                     "position=[" + presetStartPositionMillis + "]");
             // Has another start position?
@@ -700,41 +702,23 @@ public abstract class BasePlayer implements
         }
     }
 
-    /**
-     * Processes {@link ExoPlaybackException} tagged with {@link ExoPlaybackException#TYPE_SOURCE}.
-     * <br><br>
-     * If the current {@link com.google.android.exoplayer2.Timeline.Window window} is valid,
-     * then we know the error is produced by transitioning into a bad window, therefore we report
-     * an error to the play queue based on if the current error can be skipped.
-     * <br><br>
-     * This is done because ExoPlayer reports the source exceptions before window is
-     * transitioned on seamless playback. Because player error causes ExoPlayer to go
-     * back to {@link Player#STATE_IDLE STATE_IDLE}, we reset and prepare the media source
-     * again to resume playback.
-     * <br><br>
-     * In the event that this error is produced during a valid stream playback, we save the
-     * current position so the playback may be recovered and resumed manually by the user. This
-     * happens only if the playback is {@link #RECOVERY_SKIP_THRESHOLD} milliseconds until complete.
-     * <br><br>
-     * In the event of livestreaming being lagged behind for any reason, most notably pausing for
-     * too long, a {@link BehindLiveWindowException} will be produced. This will trigger a reload
-     * instead of skipping or removal.
-     * */
     private void processSourceError(final IOException error) {
         if (simpleExoPlayer == null || playQueue == null) return;
-
-        if (simpleExoPlayer.getCurrentPosition() <
-                simpleExoPlayer.getDuration() - RECOVERY_SKIP_THRESHOLD) {
         setRecovery();
-        }
 
         final Throwable cause = error.getCause();
         if (cause instanceof BehindLiveWindowException) {
             reload();
         } else if (cause instanceof UnknownHostException) {
             playQueue.error(/*isNetworkProblem=*/true);
+        } else if (isCurrentWindowValid()) {
+            playQueue.error(/*isTransitioningToBadStream=*/true);
+        } else if (cause instanceof FailedMediaSource.MediaSourceResolutionException) {
+            playQueue.error(/*recoverableWithNoAvailableStream=*/false);
+        } else if (cause instanceof FailedMediaSource.StreamInfoLoadException) {
+            playQueue.error(/*recoverableIfLoadFailsWhenNetworkIsFine=*/false);
         } else {
-            playQueue.error(isCurrentWindowValid());
+            playQueue.error(/*noIdeaWhatHappenedAndLetUserChooseWhatToDo=*/true);
         }
     }
 
@@ -787,9 +771,10 @@ public abstract class BasePlayer implements
     //////////////////////////////////////////////////////////////////////////*/
 
     @Override
-    public boolean isNearPlaybackEdge(final long timeToEndMillis) {
+    public boolean isApproachingPlaybackEdge(final long timeToEndMillis) {
         // If live, then not near playback edge
-        if (simpleExoPlayer == null || simpleExoPlayer.isCurrentWindowDynamic()) return false;
+        // If not playing, then not approaching playback edge
+        if (simpleExoPlayer == null || isLive() || !isPlaying()) return false;
 
         final long currentPositionMillis = simpleExoPlayer.getCurrentPosition();
         final long currentDurationMillis = simpleExoPlayer.getDuration();
@@ -985,22 +970,22 @@ public abstract class BasePlayer implements
 
     public void onFastRewind() {
         if (DEBUG) Log.d(TAG, "onFastRewind() called");
-        seekBy(-FAST_FORWARD_REWIND_AMOUNT);
+        seekBy(-FAST_FORWARD_REWIND_AMOUNT_MILLIS);
     }
 
     public void onFastForward() {
         if (DEBUG) Log.d(TAG, "onFastForward() called");
-        seekBy(FAST_FORWARD_REWIND_AMOUNT);
+        seekBy(FAST_FORWARD_REWIND_AMOUNT_MILLIS);
     }
 
     public void onPlayPrevious() {
         if (simpleExoPlayer == null || playQueue == null) return;
         if (DEBUG) Log.d(TAG, "onPlayPrevious() called");
 
-        /* If current playback has run for PLAY_PREV_ACTIVATION_LIMIT milliseconds,
+        /* If current playback has run for PLAY_PREV_ACTIVATION_LIMIT_MILLIS milliseconds,
         * restart current track. Also restart the track if the current track
         * is the first in a queue.*/
-        if (simpleExoPlayer.getCurrentPosition() > PLAY_PREV_ACTIVATION_LIMIT ||
+        if (simpleExoPlayer.getCurrentPosition() > PLAY_PREV_ACTIVATION_LIMIT_MILLIS ||
                 playQueue.getIndex() == 0) {
             seekToDefault();
             playQueue.offsetIndex(0);
@@ -1050,7 +1035,9 @@ public abstract class BasePlayer implements
     }
 
     public void seekToDefault() {
-        if (simpleExoPlayer != null) simpleExoPlayer.seekToDefaultPosition();
+        if (simpleExoPlayer != null) {
+            simpleExoPlayer.seekToDefaultPosition();
+        }
     }
 
     /*//////////////////////////////////////////////////////////////////////////
@@ -1091,9 +1078,9 @@ public abstract class BasePlayer implements
     private void savePlaybackState() {
         if (simpleExoPlayer == null || currentInfo == null) return;
 
-        if (simpleExoPlayer.getCurrentPosition() > RECOVERY_SKIP_THRESHOLD &&
+        if (simpleExoPlayer.getCurrentPosition() > RECOVERY_SKIP_THRESHOLD_MILLIS &&
                 simpleExoPlayer.getCurrentPosition() <
-                        simpleExoPlayer.getDuration() - RECOVERY_SKIP_THRESHOLD) {
+                        simpleExoPlayer.getDuration() - RECOVERY_SKIP_THRESHOLD_MILLIS) {
             savePlaybackState(currentInfo, simpleExoPlayer.getCurrentPosition());
         }
     }
@@ -1127,9 +1114,7 @@ public abstract class BasePlayer implements
 
     /** Checks if the current playback is a livestream AND is playing at or beyond the live edge */
     public boolean isLiveEdge() {
-        if (simpleExoPlayer == null) return false;
+        if (simpleExoPlayer == null || !isLive()) return false;
-        final boolean isLive = simpleExoPlayer.isCurrentWindowDynamic();
-        if (!isLive) return false;
 
         final Timeline currentTimeline = simpleExoPlayer.getCurrentTimeline();
         final int currentWindowIndex = simpleExoPlayer.getCurrentWindowIndex();
@@ -1143,6 +1128,16 @@ public abstract class BasePlayer implements
         return timelineWindow.getDefaultPositionMs() <= simpleExoPlayer.getCurrentPosition();
     }
 
+    public boolean isLive() {
+        if (simpleExoPlayer == null) return false;
+        try {
+            return simpleExoPlayer.isCurrentWindowDynamic();
+        } catch (@NonNull IndexOutOfBoundsException ignored) {
+            // Why would this even happen =(
+            return false;
+        }
+    }
+
     public boolean isPlaying() {
         final int state = simpleExoPlayer.getPlaybackState();
         return (state == Player.STATE_READY || state == Player.STATE_BUFFERING)
@@ -1170,10 +1165,6 @@ public abstract class BasePlayer implements
         setPlaybackParameters(speed, getPlaybackPitch());
     }
 
-    public void setPlaybackPitch(float pitch) {
-        setPlaybackParameters(getPlaybackSpeed(), pitch);
-    }
-
     public PlaybackParameters getPlaybackParameters() {
         final PlaybackParameters defaultParameters = new PlaybackParameters(1f, 1f);
         if (simpleExoPlayer == null) return defaultParameters;

app/src/main/java/org/schabi/newpipe/player/MainVideoPlayer.java

@@ -30,8 +30,10 @@ import android.os.Build;
 import android.os.Bundle;
 import android.preference.PreferenceManager;
 import android.provider.Settings;
+import android.support.annotation.ColorInt;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
+import android.support.v4.app.ActivityCompat;
 import android.support.v7.app.AppCompatActivity;
 import android.support.v7.widget.RecyclerView;
 import android.support.v7.widget.helper.ItemTouchHelper;
@@ -50,6 +52,7 @@ import android.widget.TextView;
 import android.widget.Toast;
 
 import com.google.android.exoplayer2.Player;
+import com.google.android.exoplayer2.text.CaptionStyleCompat;
 import com.google.android.exoplayer2.ui.AspectRatioFrameLayout;
 import com.google.android.exoplayer2.ui.SubtitleView;
 
@@ -59,7 +62,6 @@ import org.schabi.newpipe.extractor.stream.VideoStream;
 import org.schabi.newpipe.fragments.OnScrollBelowItemsListener;
 import org.schabi.newpipe.player.helper.PlaybackParameterDialog;
 import org.schabi.newpipe.player.helper.PlayerHelper;
-import org.schabi.newpipe.playlist.PlayQueue;
 import org.schabi.newpipe.playlist.PlayQueueItem;
 import org.schabi.newpipe.playlist.PlayQueueItemBuilder;
 import org.schabi.newpipe.playlist.PlayQueueItemHolder;
@@ -95,12 +97,12 @@ public final class MainVideoPlayer extends AppCompatActivity
 
     private GestureDetector gestureDetector;
 
-    private boolean activityPaused;
     private VideoPlayerImpl playerImpl;
 
     private SharedPreferences defaultPreferences;
 
-    @Nullable private StateSaver.SavedState savedState;
+    @Nullable private PlayerState playerState;
+    private boolean isInMultiWindow;
 
     /*//////////////////////////////////////////////////////////////////////////
     // Activity LifeCycle
@@ -135,8 +137,9 @@ public final class MainVideoPlayer extends AppCompatActivity
 
     @Override
     protected void onRestoreInstanceState(@NonNull Bundle bundle) {
+        if (DEBUG) Log.d(TAG, "onRestoreInstanceState() called");
         super.onRestoreInstanceState(bundle);
-        savedState = StateSaver.tryToRestore(bundle, this);
+        StateSaver.tryToRestore(bundle, this);
     }
 
     @Override
@@ -148,26 +151,28 @@ public final class MainVideoPlayer extends AppCompatActivity
 
     @Override
     protected void onResume() {
-        super.onResume();
         if (DEBUG) Log.d(TAG, "onResume() called");
-        if (playerImpl.getPlayer() != null && activityPaused && playerImpl.wasPlaying()
+        super.onResume();
-                && !playerImpl.isPlaying()) {
-            playerImpl.onPlay();
-        }
-        activityPaused = false;
 
-        if(globalScreenOrientationLocked()) {
+        if (globalScreenOrientationLocked()) {
-            boolean lastOrientationWasLandscape
+            boolean lastOrientationWasLandscape = defaultPreferences.getBoolean(
-                    = defaultPreferences.getBoolean(getString(R.string.last_orientation_landscape_key), false);
+                    getString(R.string.last_orientation_landscape_key), false);
             setLandscape(lastOrientationWasLandscape);
         }
-    }
 
-    @Override
+        // Upon going in or out of multiwindow mode, isInMultiWindow will always be false,
-    public void onBackPressed() {
+        // since the first onResume needs to restore the player.
-        if (DEBUG) Log.d(TAG, "onBackPressed() called");
+        // Subsequent onResume calls while multiwindow mode remains the same and the player is
-        super.onBackPressed();
+        // prepared should be ignored.
-        if (playerImpl.isPlaying()) playerImpl.getPlayer().setPlayWhenReady(false);
+        if (isInMultiWindow) return;
+        isInMultiWindow = isInMultiWindow();
+
+        if (playerState != null) {
+            playerImpl.setPlaybackQuality(playerState.getPlaybackQuality());
+            playerImpl.initPlayback(playerState.getPlayQueue(), playerState.getRepeatMode(),
+                    playerState.getPlaybackSpeed(), playerState.getPlaybackPitch(),
+                    playerState.wasPlaying());
+        }
     }
 
     @Override
@@ -180,33 +185,24 @@ public final class MainVideoPlayer extends AppCompatActivity
         }
     }
 
-    @Override
-    protected void onPause() {
-        super.onPause();
-        if (DEBUG) Log.d(TAG, "onPause() called");
-
-        if (playerImpl != null && playerImpl.getPlayer() != null && !activityPaused) {
-            playerImpl.wasPlaying = playerImpl.isPlaying();
-            playerImpl.onPause();
-        }
-        activityPaused = true;
-    }
-
     @Override
     protected void onSaveInstanceState(Bundle outState) {
+        if (DEBUG) Log.d(TAG, "onSaveInstanceState() called");
         super.onSaveInstanceState(outState);
         if (playerImpl == null) return;
 
         playerImpl.setRecovery();
-        savedState = StateSaver.tryToSave(isChangingConfigurations(), savedState,
+        playerState = new PlayerState(playerImpl.getPlayQueue(), playerImpl.getRepeatMode(),
-                outState, this);
+                playerImpl.getPlaybackSpeed(), playerImpl.getPlaybackPitch(),
+                playerImpl.getPlaybackQuality(), playerImpl.isPlaying());
+        StateSaver.tryToSave(isChangingConfigurations(), null, outState, this);
     }
 
     @Override
-    protected void onDestroy() {
+    protected void onStop() {
-        super.onDestroy();
+        if (DEBUG) Log.d(TAG, "onStop() called");
-        if (DEBUG) Log.d(TAG, "onDestroy() called");
+        super.onStop();
-        if (playerImpl != null) playerImpl.destroy();
+        playerImpl.destroy();
     }
 
     /*//////////////////////////////////////////////////////////////////////////
@@ -221,48 +217,19 @@ public final class MainVideoPlayer extends AppCompatActivity
     @Override
     public void writeTo(Queue<Object> objectsToSave) {
         if (objectsToSave == null) return;
-        objectsToSave.add(playerImpl.getPlayQueue());
+        objectsToSave.add(playerState);
-        objectsToSave.add(playerImpl.getRepeatMode());
-        objectsToSave.add(playerImpl.getPlaybackSpeed());
-        objectsToSave.add(playerImpl.getPlaybackPitch());
-        objectsToSave.add(playerImpl.getPlaybackQuality());
     }
 
     @Override
     @SuppressWarnings("unchecked")
-    public void readFrom(@NonNull Queue<Object> savedObjects) throws Exception {
+    public void readFrom(@NonNull Queue<Object> savedObjects) {
-        @NonNull final PlayQueue queue = (PlayQueue) savedObjects.poll();
+        playerState = (PlayerState) savedObjects.poll();
-        final int repeatMode = (int) savedObjects.poll();
-        final float playbackSpeed = (float) savedObjects.poll();
-        final float playbackPitch = (float) savedObjects.poll();
-        @NonNull final String playbackQuality = (String) savedObjects.poll();
-
-        playerImpl.setPlaybackQuality(playbackQuality);
-        playerImpl.initPlayback(queue, repeatMode, playbackSpeed, playbackPitch);
-
-        StateSaver.onDestroy(savedState);
     }
 
     /*//////////////////////////////////////////////////////////////////////////
     // View
     //////////////////////////////////////////////////////////////////////////*/
 
-    /**
-     * Prior to Kitkat, hiding system ui causes the player view to be overlaid and require two
-     * clicks to get rid of that invisible overlay. By showing the system UI on actions/events,
-     * that overlay is removed and the player view is put to the foreground.
-     *
-     * Post Kitkat, navbar and status bar can be pulled out by swiping the edge of
-     * screen, therefore, we can do nothing or hide the UI on actions/events.
-     * */
-    private void changeSystemUi() {
-        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
-            showSystemUi();
-        } else {
-            hideSystemUi();
-        }
-    }
-
     private void showSystemUi() {
         if (DEBUG) Log.d(TAG, "showSystemUi() called");
         if (playerImpl != null && playerImpl.queueVisible) return;
@@ -275,6 +242,14 @@ public final class MainVideoPlayer extends AppCompatActivity
         } else {
             visibility = View.STATUS_BAR_VISIBLE;
         }
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+            @ColorInt final int systenUiColor =
+                    ActivityCompat.getColor(getApplicationContext(), R.color.video_overlay_color);
+            getWindow().setStatusBarColor(systenUiColor);
+            getWindow().setNavigationBarColor(systenUiColor);
+        }
+
         getWindow().getDecorView().setSystemUiVisibility(visibility);
         getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
     }
@@ -342,6 +317,10 @@ public final class MainVideoPlayer extends AppCompatActivity
         }
     }
 
+    private boolean isInMultiWindow() {
+        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.N && isInMultiWindowMode();
+    }
+
     ////////////////////////////////////////////////////////////////////////////
     // Playback Parameters Listener
     ////////////////////////////////////////////////////////////////////////////
@@ -411,15 +390,6 @@ public final class MainVideoPlayer extends AppCompatActivity
             this.itemsListCloseButton = findViewById(R.id.playQueueClose);
             this.itemsList = findViewById(R.id.playQueue);
 
-            this.windowRootLayout = rootView.findViewById(R.id.playbackWindowRoot);
-            // Prior to Kitkat, there is no way of setting translucent navbar programmatically.
-            // Thus, fit system windows is opted instead.
-            // See https://stackoverflow.com/questions/29069070/completely-transparent-status-bar-and-navigation-bar-on-lollipop
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
-                windowRootLayout.setFitsSystemWindows(false);
-                windowRootLayout.invalidate();
-            }
-
             titleTextView.setSelected(true);
             channelTextView.setSelected(true);
 
@@ -428,20 +398,15 @@ public final class MainVideoPlayer extends AppCompatActivity
 
         @Override
         protected void setupSubtitleView(@NonNull SubtitleView view,
-                                         @NonNull String captionSizeKey) {
+                                         final float captionScale,
-            final float captionRatioInverse;
+                                         @NonNull final CaptionStyleCompat captionStyle) {
-            if (captionSizeKey.equals(getString(R.string.smaller_caption_size_key))) {
-                captionRatioInverse = 22f;
-            } else if (captionSizeKey.equals(getString(R.string.larger_caption_size_key))) {
-                captionRatioInverse = 18f;
-            } else {
-                captionRatioInverse = 20f;
-            }
-
             final DisplayMetrics metrics = context.getResources().getDisplayMetrics();
             final int minimumLength = Math.min(metrics.heightPixels, metrics.widthPixels);
+            final float captionRatioInverse = 20f + 4f * (1f - captionScale);
             view.setFixedTextSize(TypedValue.COMPLEX_UNIT_PX,
                     (float) minimumLength / captionRatioInverse);
+            view.setApplyEmbeddedStyles(captionStyle.equals(CaptionStyleCompat.DEFAULT));
+            view.setStyle(captionStyle);
         }
 
         @Override
@@ -727,7 +692,7 @@ public final class MainVideoPlayer extends AppCompatActivity
                 animatePlayButtons(true, 200);
             });
 
-            changeSystemUi();
+            showSystemUi();
             getRootView().setKeepScreenOn(false);
         }
 
@@ -900,7 +865,7 @@ public final class MainVideoPlayer extends AppCompatActivity
                 playerImpl.hideControls(150, 0);
             } else {
                 playerImpl.showControlsThenHide();
-                changeSystemUi();
+                showSystemUi();
             }
             return true;
         }

app/src/main/java/org/schabi/newpipe/player/PlayerState.java

@@ -0,0 +1,88 @@
+package org.schabi.newpipe.player;
+
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.util.Log;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonSyntaxException;
+
+import org.schabi.newpipe.playlist.PlayQueue;
+
+import java.io.Serializable;
+
+public class PlayerState implements Serializable {
+    private final static String TAG = "PlayerState";
+
+    @NonNull private final PlayQueue playQueue;
+    private final int repeatMode;
+    private final float playbackSpeed;
+    private final float playbackPitch;
+    @Nullable private final String playbackQuality;
+    private final boolean wasPlaying;
+
+    PlayerState(@NonNull final PlayQueue playQueue, final int repeatMode,
+                 final float playbackSpeed, final float playbackPitch, final boolean wasPlaying) {
+        this(playQueue, repeatMode, playbackSpeed, playbackPitch, null, wasPlaying);
+    }
+
+    PlayerState(@NonNull final PlayQueue playQueue, final int repeatMode,
+                final float playbackSpeed, final float playbackPitch,
+                @Nullable final String playbackQuality, final boolean wasPlaying) {
+        this.playQueue = playQueue;
+        this.repeatMode = repeatMode;
+        this.playbackSpeed = playbackSpeed;
+        this.playbackPitch = playbackPitch;
+        this.playbackQuality = playbackQuality;
+        this.wasPlaying = wasPlaying;
+    }
+
+    /*//////////////////////////////////////////////////////////////////////////
+    // Serdes
+    //////////////////////////////////////////////////////////////////////////*/
+
+    @Nullable
+    public static PlayerState fromJson(@NonNull final String json) {
+        try {
+            return new Gson().fromJson(json, PlayerState.class);
+        } catch (JsonSyntaxException error) {
+            Log.e(TAG, "Failed to deserialize PlayerState from json=[" + json + "]", error);
+            return null;
+        }
+    }
+
+    @NonNull
+    public String toJson() {
+        return new Gson().toJson(this);
+    }
+
+    /*//////////////////////////////////////////////////////////////////////////
+    // Getters
+    //////////////////////////////////////////////////////////////////////////*/
+
+    @NonNull
+    public PlayQueue getPlayQueue() {
+        return playQueue;
+    }
+
+    public int getRepeatMode() {
+        return repeatMode;
+    }
+
+    public float getPlaybackSpeed() {
+        return playbackSpeed;
+    }
+
+    public float getPlaybackPitch() {
+        return playbackPitch;
+    }
+
+    @Nullable
+    public String getPlaybackQuality() {
+        return playbackQuality;
+    }
+
+    public boolean wasPlaying() {
+        return wasPlaying;
+    }
+}

app/src/main/java/org/schabi/newpipe/player/PopupVideoPlayer.java

@@ -52,6 +52,7 @@ import android.widget.TextView;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.PlaybackParameters;
 import com.google.android.exoplayer2.Player;
+import com.google.android.exoplayer2.text.CaptionStyleCompat;
 import com.google.android.exoplayer2.ui.AspectRatioFrameLayout;
 import com.google.android.exoplayer2.ui.SubtitleView;
 
@@ -397,14 +398,12 @@ public final class PopupVideoPlayer extends Service {
 
         @Override
         protected void setupSubtitleView(@NonNull SubtitleView view,
-                                         @NonNull String captionSizeKey) {
+                                         final float captionScale,
-            float captionRatio = SubtitleView.DEFAULT_TEXT_SIZE_FRACTION;
+                                         @NonNull final CaptionStyleCompat captionStyle) {
-            if (captionSizeKey.equals(getString(R.string.smaller_caption_size_key))) {
+            float captionRatio = (captionScale - 1f) / 5f + 1f;
-                captionRatio *= 0.9;
+            view.setFractionalTextSize(SubtitleView.DEFAULT_TEXT_SIZE_FRACTION * captionRatio);
-            } else if (captionSizeKey.equals(getString(R.string.larger_caption_size_key))) {
+            view.setApplyEmbeddedStyles(captionStyle.equals(CaptionStyleCompat.DEFAULT));
-                captionRatio *= 1.1;
+            view.setStyle(captionStyle);
-            }
-            view.setFractionalTextSize(captionRatio);
         }
 
         @Override

app/src/main/java/org/schabi/newpipe/player/ServicePlayerActivity.java

@@ -32,6 +32,7 @@ import org.schabi.newpipe.fragments.OnScrollBelowItemsListener;
 import org.schabi.newpipe.fragments.local.dialog.PlaylistAppendDialog;
 import org.schabi.newpipe.player.event.PlayerEventListener;
 import org.schabi.newpipe.player.helper.PlaybackParameterDialog;
+import org.schabi.newpipe.playlist.PlayQueueAdapter;
 import org.schabi.newpipe.playlist.PlayQueueItem;
 import org.schabi.newpipe.playlist.PlayQueueItemBuilder;
 import org.schabi.newpipe.playlist.PlayQueueItemHolder;
@@ -40,6 +41,9 @@ import org.schabi.newpipe.util.Localization;
 import org.schabi.newpipe.util.NavigationHelper;
 import org.schabi.newpipe.util.ThemeHelper;
 
+import java.util.Collections;
+import java.util.List;
+
 import static org.schabi.newpipe.player.helper.PlayerHelper.formatPitch;
 import static org.schabi.newpipe.player.helper.PlayerHelper.formatSpeed;
 
@@ -151,7 +155,7 @@ public abstract class ServicePlayerActivity extends AppCompatActivity
                 finish();
                 return true;
             case R.id.action_append_playlist:
-                appendToPlaylist();
+                appendAllToPlaylist();
                 return true;
             case R.id.action_settings:
                 NavigationHelper.openSettings(this);
@@ -187,13 +191,6 @@ public abstract class ServicePlayerActivity extends AppCompatActivity
         ).addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
     }
 
-    private void appendToPlaylist() {
-        if (this.player != null && this.player.getPlayQueue() != null) {
-            PlaylistAppendDialog.fromPlayQueueItems(this.player.getPlayQueue().getStreams())
-                    .show(getSupportFragmentManager(), getTag());
-        }
-    }
-
     ////////////////////////////////////////////////////////////////////////////
     // Service Connection
     ////////////////////////////////////////////////////////////////////////////
@@ -319,7 +316,8 @@ public abstract class ServicePlayerActivity extends AppCompatActivity
 
     private void buildItemPopupMenu(final PlayQueueItem item, final View view) {
         final PopupMenu menu = new PopupMenu(this, view);
-        final MenuItem remove = menu.getMenu().add(RECYCLER_ITEM_POPUP_MENU_GROUP_ID, 0, Menu.NONE, R.string.play_queue_remove);
+        final MenuItem remove = menu.getMenu().add(RECYCLER_ITEM_POPUP_MENU_GROUP_ID, /*pos=*/0,
+                Menu.NONE, R.string.play_queue_remove);
         remove.setOnMenuItemClickListener(menuItem -> {
             if (player == null) return false;
 
@@ -328,12 +326,20 @@ public abstract class ServicePlayerActivity extends AppCompatActivity
             return true;
         });
 
-        final MenuItem detail = menu.getMenu().add(RECYCLER_ITEM_POPUP_MENU_GROUP_ID, 1, Menu.NONE, R.string.play_queue_stream_detail);
+        final MenuItem detail = menu.getMenu().add(RECYCLER_ITEM_POPUP_MENU_GROUP_ID, /*pos=*/1,
+                Menu.NONE, R.string.play_queue_stream_detail);
         detail.setOnMenuItemClickListener(menuItem -> {
             onOpenDetail(item.getServiceId(), item.getUrl(), item.getTitle());
             return true;
         });
 
+        final MenuItem append = menu.getMenu().add(RECYCLER_ITEM_POPUP_MENU_GROUP_ID, /*pos=*/2,
+                Menu.NONE, R.string.append_playlist);
+        append.setOnMenuItemClickListener(menuItem -> {
+            openPlaylistAppendDialog(Collections.singletonList(item));
+            return true;
+        });
+
         menu.show();
     }
 
@@ -488,6 +494,21 @@ public abstract class ServicePlayerActivity extends AppCompatActivity
         seeking = false;
     }
 
+    ////////////////////////////////////////////////////////////////////////////
+    // Playlist append
+    ////////////////////////////////////////////////////////////////////////////
+
+    private void appendAllToPlaylist() {
+        if (player != null && player.getPlayQueue() != null) {
+            openPlaylistAppendDialog(player.getPlayQueue().getStreams());
+        }
+    }
+
+    private void openPlaylistAppendDialog(final List<PlayQueueItem> playlist) {
+        PlaylistAppendDialog.fromPlayQueueItems(playlist)
+                .show(getSupportFragmentManager(), getTag());
+    }
+
     ////////////////////////////////////////////////////////////////////////////
     // Binding Service Listener
     ////////////////////////////////////////////////////////////////////////////
@@ -497,6 +518,7 @@ public abstract class ServicePlayerActivity extends AppCompatActivity
         onStateChanged(state);
         onPlayModeChanged(repeatMode, shuffled);
         onPlaybackParameterChanged(parameters);
+        onMaybePlaybackAdapterChanged();
     }
 
     @Override
@@ -609,4 +631,12 @@ public abstract class ServicePlayerActivity extends AppCompatActivity
             playbackPitchButton.setText(formatPitch(parameters.pitch));
         }
     }
+
+    private void onMaybePlaybackAdapterChanged() {
+        if (itemsList == null || player == null) return;
+        final PlayQueueAdapter maybeNewAdapter = player.getPlayQueueAdapter();
+        if (maybeNewAdapter != null && itemsList.getAdapter() != maybeNewAdapter) {
+            itemsList.setAdapter(maybeNewAdapter);
+        }
+    }
 }

app/src/main/java/org/schabi/newpipe/player/VideoPlayer.java

@@ -32,7 +32,6 @@ import android.graphics.PorterDuff;
 import android.net.Uri;
 import android.os.Build;
 import android.os.Handler;
-import android.preference.PreferenceManager;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.v4.content.ContextCompat;
@@ -55,6 +54,7 @@ import com.google.android.exoplayer2.source.MediaSource;
 import com.google.android.exoplayer2.source.MergingMediaSource;
 import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.TrackGroupArray;
+import com.google.android.exoplayer2.text.CaptionStyleCompat;
 import com.google.android.exoplayer2.trackselection.TrackSelectionArray;
 import com.google.android.exoplayer2.ui.AspectRatioFrameLayout;
 import com.google.android.exoplayer2.ui.SubtitleView;
@@ -189,10 +189,10 @@ public abstract class VideoPlayer extends BasePlayer
         this.qualityTextView = rootView.findViewById(R.id.qualityTextView);
 
         this.subtitleView = rootView.findViewById(R.id.subtitleView);
-        final String captionSizeKey = PreferenceManager.getDefaultSharedPreferences(context)
+
-                .getString(context.getString(R.string.caption_size_key),
+        final float captionScale = PlayerHelper.getCaptionScale(context);
-                        context.getString(R.string.caption_size_default));
+        final CaptionStyleCompat captionStyle = PlayerHelper.getCaptionStyle(context);
-        setupSubtitleView(subtitleView, captionSizeKey);
+        setupSubtitleView(subtitleView, captionScale, captionStyle);
 
         this.resizeView =  rootView.findViewById(R.id.resizeTextView);
         resizeView.setText(PlayerHelper.resizeTypeOf(context, aspectRatioFrameLayout.getResizeMode()));
@@ -214,7 +214,8 @@ public abstract class VideoPlayer extends BasePlayer
     }
 
     protected abstract void setupSubtitleView(@NonNull SubtitleView view,
-                                              @NonNull String captionSizeKey);
+                                              final float captionScale,
+                                              @NonNull final CaptionStyleCompat captionStyle);
 
     @Override
     public void initListeners() {
@@ -228,8 +229,8 @@ public abstract class VideoPlayer extends BasePlayer
     }
 
     @Override
-    public void initPlayer() {
+    public void initPlayer(final boolean playOnReady) {
-        super.initPlayer();
+        super.initPlayer(playOnReady);
 
         // Setup video view
         simpleExoPlayer.setVideoSurfaceView(surfaceView);

app/src/main/java/org/schabi/newpipe/player/helper/MediaSessionManager.java

@@ -1,8 +1,12 @@
 package org.schabi.newpipe.player.helper;
 
 import android.content.Context;
+import android.content.Intent;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+import android.support.v4.media.session.MediaButtonReceiver;
 import android.support.v4.media.session.MediaSessionCompat;
+import android.view.KeyEvent;
 
 import com.google.android.exoplayer2.Player;
 import com.google.android.exoplayer2.ext.mediasession.MediaSessionConnector;
@@ -15,8 +19,8 @@ import org.schabi.newpipe.player.mediasession.PlayQueuePlaybackController;
 public class MediaSessionManager {
     private static final String TAG = "MediaSessionManager";
 
-    private final MediaSessionCompat mediaSession;
+    @NonNull private final MediaSessionCompat mediaSession;
-    private final MediaSessionConnector sessionConnector;
+    @NonNull private final MediaSessionConnector sessionConnector;
 
     public MediaSessionManager(@NonNull final Context context,
                                @NonNull final Player player,
@@ -28,11 +32,9 @@ public class MediaSessionManager {
         this.sessionConnector.setPlayer(player, new DummyPlaybackPreparer());
     }
 
-    public MediaSessionCompat getMediaSession() {
+    @Nullable
-        return mediaSession;
+    @SuppressWarnings("UnusedReturnValue")
-    }
+    public KeyEvent handleMediaButtonIntent(final Intent intent) {
-
+        return MediaButtonReceiver.handleIntent(mediaSession, intent);
-    public MediaSessionConnector getSessionConnector() {
-        return sessionConnector;
     }
 }

app/src/main/java/org/schabi/newpipe/player/helper/PlayerHelper.java

@@ -2,12 +2,18 @@ package org.schabi.newpipe.player.helper;
 
 import android.content.Context;
 import android.content.SharedPreferences;
+import android.os.Build;
 import android.preference.PreferenceManager;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
+import android.view.accessibility.CaptioningManager;
 
 import com.google.android.exoplayer2.SeekParameters;
+import com.google.android.exoplayer2.trackselection.AdaptiveTrackSelection;
+import com.google.android.exoplayer2.trackselection.TrackSelection;
+import com.google.android.exoplayer2.text.CaptionStyleCompat;
 import com.google.android.exoplayer2.ui.AspectRatioFrameLayout;
+import com.google.android.exoplayer2.upstream.BandwidthMeter;
 import com.google.android.exoplayer2.util.MimeTypes;
 
 import org.schabi.newpipe.R;
@@ -203,6 +209,16 @@ public class PlayerHelper {
         return 60000;
     }
 
+    public static TrackSelection.Factory getQualitySelector(@NonNull final Context context,
+                                                            @NonNull final BandwidthMeter meter) {
+        return new AdaptiveTrackSelection.Factory(meter,
+                AdaptiveTrackSelection.DEFAULT_MAX_INITIAL_BITRATE,
+                /*bufferDurationRequiredForQualityIncrease=*/1000,
+                AdaptiveTrackSelection.DEFAULT_MAX_DURATION_FOR_QUALITY_DECREASE_MS,
+                AdaptiveTrackSelection.DEFAULT_MIN_DURATION_TO_RETAIN_AFTER_DISCARD_MS,
+                AdaptiveTrackSelection.DEFAULT_BANDWIDTH_FRACTION);
+    }
+
     public static boolean isUsingDSP(@NonNull final Context context) {
         return true;
     }
@@ -215,6 +231,35 @@ public class PlayerHelper {
         return 2500;
     }
 
+    @NonNull
+    public static CaptionStyleCompat getCaptionStyle(@NonNull final Context context) {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) return CaptionStyleCompat.DEFAULT;
+
+        final CaptioningManager captioningManager = (CaptioningManager)
+                context.getSystemService(Context.CAPTIONING_SERVICE);
+        if (captioningManager == null || !captioningManager.isEnabled()) {
+            return CaptionStyleCompat.DEFAULT;
+        }
+
+        return CaptionStyleCompat.createFromCaptionStyle(captioningManager.getUserStyle());
+    }
+
+    /**
+     * System font scaling:
+     * Very small - 0.25f, Small - 0.5f, Normal - 1.0f, Large - 1.5f, Very Large - 2.0f
+     * */
+    @NonNull
+    public static float getCaptionScale(@NonNull final Context context) {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) return 1f;
+
+        final CaptioningManager captioningManager = (CaptioningManager)
+                context.getSystemService(Context.CAPTIONING_SERVICE);
+        if (captioningManager == null || !captioningManager.isEnabled()) {
+            return 1f;
+        }
+
+        return captioningManager.getFontScale();
+    }
     ////////////////////////////////////////////////////////////////////////////
     // Private helpers
     ////////////////////////////////////////////////////////////////////////////

app/src/main/java/org/schabi/newpipe/player/mediasource/FailedMediaSource.java

@@ -14,13 +14,35 @@ import java.io.IOException;
 public class FailedMediaSource implements ManagedMediaSource {
     private final String TAG = "FailedMediaSource@" + Integer.toHexString(hashCode());
 
+    public static class FailedMediaSourceException extends Exception {
+        FailedMediaSourceException(String message) {
+            super(message);
+        }
+
+        FailedMediaSourceException(Throwable cause) {
+            super(cause);
+        }
+    }
+
+    public static final class MediaSourceResolutionException extends FailedMediaSourceException {
+        public MediaSourceResolutionException(String message) {
+            super(message);
+        }
+    }
+
+    public static final class StreamInfoLoadException extends FailedMediaSourceException {
+        public StreamInfoLoadException(Throwable cause) {
+            super(cause);
+        }
+    }
+
     private final PlayQueueItem playQueueItem;
-    private final Throwable error;
+    private final FailedMediaSourceException error;
 
     private final long retryTimestamp;
 
     public FailedMediaSource(@NonNull final PlayQueueItem playQueueItem,
-                             @NonNull final Throwable error,
+                             @NonNull final FailedMediaSourceException error,
                              final long retryTimestamp) {
         this.playQueueItem = playQueueItem;
         this.error = error;
@@ -32,7 +54,7 @@ public class FailedMediaSource implements ManagedMediaSource {
      * The error will always be propagated to ExoPlayer.
      * */
     public FailedMediaSource(@NonNull final PlayQueueItem playQueueItem,
-                             @NonNull final Throwable error) {
+                             @NonNull final FailedMediaSourceException error) {
         this.playQueueItem = playQueueItem;
         this.error = error;
         this.retryTimestamp = Long.MAX_VALUE;
@@ -42,7 +64,7 @@ public class FailedMediaSource implements ManagedMediaSource {
         return playQueueItem;
     }
 
-    public Throwable getError() {
+    public FailedMediaSourceException getError() {
         return error;
     }
 

app/src/main/java/org/schabi/newpipe/player/mediasource/ManagedMediaSourcePlaylist.java

@@ -0,0 +1,135 @@
+package org.schabi.newpipe.player.mediasource;
+
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import com.google.android.exoplayer2.source.DynamicConcatenatingMediaSource;
+import com.google.android.exoplayer2.source.ShuffleOrder;
+
+public class ManagedMediaSourcePlaylist {
+    @NonNull private final DynamicConcatenatingMediaSource internalSource;
+
+    public ManagedMediaSourcePlaylist() {
+        internalSource = new DynamicConcatenatingMediaSource(/*isPlaylistAtomic=*/false,
+                new ShuffleOrder.UnshuffledShuffleOrder(0));
+    }
+
+    /*//////////////////////////////////////////////////////////////////////////
+    // MediaSource Delegations
+    //////////////////////////////////////////////////////////////////////////*/
+
+    public int size() {
+        return internalSource.getSize();
+    }
+
+    /**
+     * Returns the {@link ManagedMediaSource} at the given index of the playlist.
+     * If the index is invalid, then null is returned.
+     * */
+    @Nullable
+    public ManagedMediaSource get(final int index) {
+        return (index < 0 || index >= size()) ?
+                null : (ManagedMediaSource) internalSource.getMediaSource(index);
+    }
+
+    public void dispose() {
+        internalSource.releaseSource();
+    }
+
+    @NonNull
+    public DynamicConcatenatingMediaSource getParentMediaSource() {
+        return internalSource;
+    }
+
+    /*//////////////////////////////////////////////////////////////////////////
+    // Playlist Manipulation
+    //////////////////////////////////////////////////////////////////////////*/
+
+    /**
+     * Expands the {@link DynamicConcatenatingMediaSource} by appending it with a
+     * {@link PlaceholderMediaSource}.
+     *
+     * @see #append(ManagedMediaSource)
+     * */
+    public synchronized void expand() {
+        append(new PlaceholderMediaSource());
+    }
+
+    /**
+     * Appends a {@link ManagedMediaSource} to the end of {@link DynamicConcatenatingMediaSource}.
+     * @see DynamicConcatenatingMediaSource#addMediaSource
+     * */
+    public synchronized void append(@NonNull final ManagedMediaSource source) {
+        internalSource.addMediaSource(source);
+    }
+
+    /**
+     * Removes a {@link ManagedMediaSource} from {@link DynamicConcatenatingMediaSource}
+     * at the given index. If this index is out of bound, then the removal is ignored.
+     * @see DynamicConcatenatingMediaSource#removeMediaSource(int)
+     * */
+    public synchronized void remove(final int index) {
+        if (index < 0 || index > internalSource.getSize()) return;
+
+        internalSource.removeMediaSource(index);
+    }
+
+    /**
+     * Moves a {@link ManagedMediaSource} in {@link DynamicConcatenatingMediaSource}
+     * from the given source index to the target index. If either index is out of bound,
+     * then the call is ignored.
+     * @see DynamicConcatenatingMediaSource#moveMediaSource(int, int)
+     * */
+    public synchronized void move(final int source, final int target) {
+        if (source < 0 || target < 0) return;
+        if (source >= internalSource.getSize() || target >= internalSource.getSize()) return;
+
+        internalSource.moveMediaSource(source, target);
+    }
+
+    /**
+     * Invalidates the {@link ManagedMediaSource} at the given index by replacing it
+     * with a {@link PlaceholderMediaSource}.
+     * @see #update(int, ManagedMediaSource, Runnable)
+     * */
+    public synchronized void invalidate(final int index,
+                                        @Nullable final Runnable finalizingAction) {
+        if (get(index) instanceof PlaceholderMediaSource) return;
+        update(index, new PlaceholderMediaSource(), finalizingAction);
+    }
+
+    /**
+     * Updates the {@link ManagedMediaSource} in {@link DynamicConcatenatingMediaSource}
+     * at the given index with a given {@link ManagedMediaSource}.
+     * @see #update(int, ManagedMediaSource, Runnable)
+     * */
+    public synchronized void update(final int index, @NonNull final ManagedMediaSource source) {
+        update(index, source, /*doNothing=*/null);
+    }
+
+    /**
+     * Updates the {@link ManagedMediaSource} in {@link DynamicConcatenatingMediaSource}
+     * at the given index with a given {@link ManagedMediaSource}. If the index is out of bound,
+     * then the replacement is ignored.
+     * @see DynamicConcatenatingMediaSource#addMediaSource
+     * @see DynamicConcatenatingMediaSource#removeMediaSource(int, Runnable)
+     * */
+    public synchronized void update(final int index, @NonNull final ManagedMediaSource source,
+                                    @Nullable final Runnable finalizingAction) {
+        if (index < 0 || index >= internalSource.getSize()) return;
+
+        // Add and remove are sequential on the same thread, therefore here, the exoplayer
+        // message queue must receive and process add before remove, effectively treating them
+        // as atomic.
+
+        // Since the finalizing action occurs strictly after the timeline has completed
+        // all its changes on the playback thread, thus, it is possible, in the meantime,
+        // other calls that modifies the playlist media source occur in between. This makes
+        // it unsafe to call remove as the finalizing action of add.
+        internalSource.addMediaSource(index + 1, source);
+
+        // Because of the above race condition, it is thus only safe to synchronize the player
+        // in the finalizing action AFTER the removal is complete and the timeline has changed.
+        internalSource.removeMediaSource(index, finalizingAction);
+    }
+}

app/src/main/java/org/schabi/newpipe/player/playback/MediaSourceManager.java

@@ -2,11 +2,11 @@ package org.schabi.newpipe.player.playback;
 
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
+import android.support.v4.util.ArraySet;
 import android.util.Log;
 
 import com.google.android.exoplayer2.source.DynamicConcatenatingMediaSource;
 import com.google.android.exoplayer2.source.MediaSource;
-import com.google.android.exoplayer2.source.ShuffleOrder;
 
 import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
@@ -14,6 +14,7 @@ import org.schabi.newpipe.extractor.stream.StreamInfo;
 import org.schabi.newpipe.player.mediasource.FailedMediaSource;
 import org.schabi.newpipe.player.mediasource.LoadedMediaSource;
 import org.schabi.newpipe.player.mediasource.ManagedMediaSource;
+import org.schabi.newpipe.player.mediasource.ManagedMediaSourcePlaylist;
 import org.schabi.newpipe.player.mediasource.PlaceholderMediaSource;
 import org.schabi.newpipe.playlist.PlayQueue;
 import org.schabi.newpipe.playlist.PlayQueueItem;
@@ -23,8 +24,10 @@ import org.schabi.newpipe.playlist.events.RemoveEvent;
 import org.schabi.newpipe.playlist.events.ReorderEvent;
 import org.schabi.newpipe.util.ServiceHelper;
 
+import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
-import java.util.HashSet;
+import java.util.List;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -37,8 +40,11 @@ import io.reactivex.disposables.Disposable;
 import io.reactivex.disposables.SerialDisposable;
 import io.reactivex.functions.Consumer;
 import io.reactivex.internal.subscriptions.EmptySubscription;
+import io.reactivex.schedulers.Schedulers;
 import io.reactivex.subjects.PublishSubject;
 
+import static org.schabi.newpipe.player.mediasource.FailedMediaSource.MediaSourceResolutionException;
+import static org.schabi.newpipe.player.mediasource.FailedMediaSource.StreamInfoLoadException;
 import static org.schabi.newpipe.playlist.PlayQueue.DEBUG;
 
 public class MediaSourceManager {
@@ -52,7 +58,6 @@ public class MediaSourceManager {
      * streams before will only be cached for future usage.
      *
      * @see #onMediaSourceReceived(PlayQueueItem, ManagedMediaSource)
-     * @see #update(int, MediaSource, Runnable)
      * */
     private final static int WINDOW_SIZE = 1;
 
@@ -103,7 +108,7 @@ public class MediaSourceManager {
 
     @NonNull private final AtomicBoolean isBlocked;
 
-    @NonNull private DynamicConcatenatingMediaSource sources;
+    @NonNull private ManagedMediaSourcePlaylist playlist;
 
     public MediaSourceManager(@NonNull final PlaybackListener listener,
                               @NonNull final PlayQueue playQueue) {
@@ -143,9 +148,9 @@ public class MediaSourceManager {
 
         this.isBlocked = new AtomicBoolean(false);
 
-        this.sources = new DynamicConcatenatingMediaSource();
+        this.playlist = new ManagedMediaSourcePlaylist();
 
-        this.loadingItems = Collections.synchronizedSet(new HashSet<>());
+        this.loadingItems = Collections.synchronizedSet(new ArraySet<>());
 
         playQueue.getBroadcastReceiver()
                 .observeOn(AndroidSchedulers.mainThread())
@@ -167,7 +172,7 @@ public class MediaSourceManager {
         playQueueReactor.cancel();
         loaderReactor.dispose();
         syncReactor.dispose();
-        sources.releaseSource();
+        playlist.dispose();
     }
 
     /*//////////////////////////////////////////////////////////////////////////
@@ -215,17 +220,18 @@ public class MediaSourceManager {
                 break;
             case REMOVE:
                 final RemoveEvent removeEvent = (RemoveEvent) event;
-                remove(removeEvent.getRemoveIndex());
+                playlist.remove(removeEvent.getRemoveIndex());
                 break;
             case MOVE:
                 final MoveEvent moveEvent = (MoveEvent) event;
-                move(moveEvent.getFromIndex(), moveEvent.getToIndex());
+                playlist.move(moveEvent.getFromIndex(), moveEvent.getToIndex());
                 break;
             case REORDER:
                 // Need to move to ensure the playing index from play queue matches that of
                 // the source timeline, and then window correction can take care of the rest
                 final ReorderEvent reorderEvent = (ReorderEvent) event;
-                move(reorderEvent.getFromSelectedIndex(), reorderEvent.getToSelectedIndex());
+                playlist.move(reorderEvent.getFromSelectedIndex(),
+                        reorderEvent.getToSelectedIndex());
                 break;
             case RECOVERY:
             default:
@@ -266,10 +272,11 @@ public class MediaSourceManager {
     }
 
     private boolean isPlaybackReady() {
-        if (sources.getSize() != playQueue.size()) return false;
+        if (playlist.size() != playQueue.size()) return false;
+
+        final ManagedMediaSource mediaSource = playlist.get(playQueue.getIndex());
+        if (mediaSource == null) return false;
 
-        final ManagedMediaSource mediaSource =
-                (ManagedMediaSource) sources.getMediaSource(playQueue.getIndex());
         final PlayQueueItem playQueueItem = playQueue.getItem();
         return mediaSource.isStreamEqual(playQueueItem);
     }
@@ -288,9 +295,9 @@ public class MediaSourceManager {
     private void maybeUnblock() {
         if (DEBUG) Log.d(TAG, "maybeUnblock() called.");
 
-        if (isPlayQueueReady() && isPlaybackReady() && isBlocked.get()) {
+        if (isBlocked.get()) {
             isBlocked.set(false);
-            playbackListener.onPlaybackUnblock(sources);
+            playbackListener.onPlaybackUnblock(playlist.getParentMediaSource());
         }
     }
 
@@ -299,10 +306,10 @@ public class MediaSourceManager {
     //////////////////////////////////////////////////////////////////////////*/
 
     private void maybeSync() {
-        if (DEBUG) Log.d(TAG, "onPlaybackSynchronize() called.");
+        if (DEBUG) Log.d(TAG, "maybeSync() called.");
 
         final PlayQueueItem currentItem = playQueue.getItem();
-        if (isBlocked.get() || !isPlaybackReady() || currentItem == null) return;
+        if (isBlocked.get() || currentItem == null) return;
 
         final Consumer<StreamInfo> onSuccess = info -> syncInternal(currentItem, info);
         final Consumer<Throwable> onError = throwable -> syncInternal(currentItem, null);
@@ -321,10 +328,12 @@ public class MediaSourceManager {
         }
     }
 
-    private void maybeSynchronizePlayer() {
+    private synchronized void maybeSynchronizePlayer() {
+        if (isPlayQueueReady() && isPlaybackReady()) {
             maybeUnblock();
             maybeSync();
         }
+    }
 
     /*//////////////////////////////////////////////////////////////////////////
     // MediaSource Loading
@@ -332,12 +341,14 @@ public class MediaSourceManager {
 
     private Observable<Long> getEdgeIntervalSignal() {
         return Observable.interval(progressUpdateIntervalMillis, TimeUnit.MILLISECONDS)
-                .filter(ignored -> playbackListener.isNearPlaybackEdge(playbackNearEndGapMillis));
+                .filter(ignored ->
+                        playbackListener.isApproachingPlaybackEdge(playbackNearEndGapMillis));
     }
 
     private Disposable getDebouncedLoader() {
         return debouncedSignal.mergeWith(nearEndIntervalSignal)
                 .debounce(loadDebounceMillis, TimeUnit.MILLISECONDS)
+                .subscribeOn(Schedulers.single())
                 .observeOn(AndroidSchedulers.mainThread())
                 .subscribe(timestamp -> loadImmediate());
     }
@@ -348,42 +359,21 @@ public class MediaSourceManager {
 
     private void loadImmediate() {
         if (DEBUG) Log.d(TAG, "MediaSource - loadImmediate() called");
-        // The current item has higher priority
+        final ItemsToLoad itemsToLoad = getItemsToLoad(playQueue, WINDOW_SIZE);
-        final int currentIndex = playQueue.getIndex();
+        if (itemsToLoad == null) return;
-        final PlayQueueItem currentItem = playQueue.getItem(currentIndex);
-        if (currentItem == null) return;
 
-        // Evict the items being loaded to free up memory
+        // Evict the previous items being loaded to free up memory, before start loading new ones
-        if (loaderReactor.size() > MAXIMUM_LOADER_SIZE) {
+        maybeClearLoaders();
-            loaderReactor.clear();
-            loadingItems.clear();
-        }
-        maybeLoadItem(currentItem);
 
-        // The rest are just for seamless playback
+        maybeLoadItem(itemsToLoad.center);
-        // Although timeline is not updated prior to the current index, these sources are still
+        for (final PlayQueueItem item : itemsToLoad.neighbors) {
-        // loaded into the cache for faster retrieval at a potentially later time.
-        final int leftBound = Math.max(0, currentIndex - WINDOW_SIZE);
-        final int rightLimit = currentIndex + WINDOW_SIZE + 1;
-        final int rightBound = Math.min(playQueue.size(), rightLimit);
-        final Set<PlayQueueItem> items = new HashSet<>(
-                playQueue.getStreams().subList(leftBound,rightBound));
-
-        // Do a round robin
-        final int excess = rightLimit - playQueue.size();
-        if (excess >= 0) {
-            items.addAll(playQueue.getStreams().subList(0, Math.min(playQueue.size(), excess)));
-        }
-        items.remove(currentItem);
-
-        for (final PlayQueueItem item : items) {
             maybeLoadItem(item);
         }
     }
 
     private void maybeLoadItem(@NonNull final PlayQueueItem item) {
         if (DEBUG) Log.d(TAG, "maybeLoadItem() called.");
-        if (playQueue.indexOf(item) >= sources.getSize()) return;
+        if (playQueue.indexOf(item) >= playlist.size()) return;
 
         if (!loadingItems.contains(item) && isCorrectionNeeded(item)) {
             if (DEBUG) Log.d(TAG, "MediaSource - Loading=[" + item.getTitle() +
@@ -402,19 +392,19 @@ public class MediaSourceManager {
         return stream.getStream().map(streamInfo -> {
             final MediaSource source = playbackListener.sourceOf(stream, streamInfo);
             if (source == null) {
-                final Exception exception = new IllegalStateException(
+                final String message = "Unable to resolve source from stream info." +
-                        "Unable to resolve source from stream info." +
                         " URL: " + stream.getUrl() +
                         ", audio count: " + streamInfo.getAudioStreams().size() +
                         ", video count: " + streamInfo.getVideoOnlyStreams().size() +
-                                streamInfo.getVideoStreams().size());
+                        streamInfo.getVideoStreams().size();
-                return new FailedMediaSource(stream, exception);
+                return new FailedMediaSource(stream, new MediaSourceResolutionException(message));
             }
 
             final long expiration = System.currentTimeMillis() +
                     ServiceHelper.getCacheExpirationMillis(streamInfo.getServiceId());
             return new LoadedMediaSource(source, stream, expiration);
-        }).onErrorReturn(throwable -> new FailedMediaSource(stream, throwable));
+        }).onErrorReturn(throwable -> new FailedMediaSource(stream,
+                new StreamInfoLoadException(throwable)));
     }
 
     private void onMediaSourceReceived(@NonNull final PlayQueueItem item,
@@ -426,10 +416,10 @@ public class MediaSourceManager {
 
         final int itemIndex = playQueue.indexOf(item);
         // Only update the playlist timeline for items at the current index or after.
-        if (itemIndex >= playQueue.getIndex() && isCorrectionNeeded(item)) {
+        if (isCorrectionNeeded(item)) {
             if (DEBUG) Log.d(TAG, "MediaSource - Updating index=[" + itemIndex + "] with " +
                     "title=[" + item.getTitle() + "] at url=[" + item.getUrl() + "]");
-            update(itemIndex, mediaSource, this::maybeSynchronizePlayer);
+            playlist.update(itemIndex, mediaSource, this::maybeSynchronizePlayer);
         }
     }
 
@@ -445,10 +435,8 @@ public class MediaSourceManager {
      * */
     private boolean isCorrectionNeeded(@NonNull final PlayQueueItem item) {
         final int index = playQueue.indexOf(item);
-        if (index == -1 || index >= sources.getSize()) return false;
+        final ManagedMediaSource mediaSource = playlist.get(index);
-
+        return mediaSource != null && mediaSource.shouldBeReplacedWith(item,
-        final ManagedMediaSource mediaSource = (ManagedMediaSource) sources.getMediaSource(index);
-        return mediaSource.shouldBeReplacedWith(item,
                 /*mightBeInProgress=*/index != playQueue.getIndex());
     }
 
@@ -465,10 +453,9 @@ public class MediaSourceManager {
      * */
     private void maybeRenewCurrentIndex() {
         final int currentIndex = playQueue.getIndex();
-        if (sources.getSize() <= currentIndex) return;
+        final ManagedMediaSource currentSource = playlist.get(currentIndex);
+        if (currentSource == null) return;
 
-        final ManagedMediaSource currentSource =
-                (ManagedMediaSource) sources.getMediaSource(currentIndex);
         final PlayQueueItem currentItem = playQueue.getItem();
         if (!currentSource.shouldBeReplacedWith(currentItem, /*canInterruptOnRenew=*/true)) {
             maybeSynchronizePlayer();
@@ -477,7 +464,16 @@ public class MediaSourceManager {
 
         if (DEBUG) Log.d(TAG, "MediaSource - Reloading currently playing, " +
                 "index=[" + currentIndex + "], item=[" + currentItem.getTitle() + "]");
-        update(currentIndex, new PlaceholderMediaSource(), this::loadImmediate);
+        playlist.invalidate(currentIndex, this::loadImmediate);
+    }
+
+    private void maybeClearLoaders() {
+        if (DEBUG) Log.d(TAG, "MediaSource - maybeClearLoaders() called.");
+        if (!loadingItems.contains(playQueue.getItem()) &&
+                loaderReactor.size() > MAXIMUM_LOADER_SIZE) {
+            loaderReactor.clear();
+            loadingItems.clear();
+        }
     }
     /*//////////////////////////////////////////////////////////////////////////
     // MediaSource Playlist Helpers
@@ -486,72 +482,55 @@ public class MediaSourceManager {
     private void resetSources() {
         if (DEBUG) Log.d(TAG, "resetSources() called.");
 
-        this.sources.releaseSource();
+        playlist.dispose();
-        this.sources = new DynamicConcatenatingMediaSource(false,
+        playlist = new ManagedMediaSourcePlaylist();
-                // Shuffling is done on PlayQueue, thus no need to use ExoPlayer's shuffle order
-                new ShuffleOrder.UnshuffledShuffleOrder(0));
     }
 
     private void populateSources() {
         if (DEBUG) Log.d(TAG, "populateSources() called.");
-        if (sources.getSize() >= playQueue.size()) return;
+        while (playlist.size() < playQueue.size()) {
-
+            playlist.expand();
-        for (int index = sources.getSize() - 1; index < playQueue.size(); index++) {
-            emplace(index, new PlaceholderMediaSource());
         }
     }
 
     /*//////////////////////////////////////////////////////////////////////////
-    // MediaSource Playlist Manipulation
+    // Manager Helpers
     //////////////////////////////////////////////////////////////////////////*/
+    @Nullable
+    private static ItemsToLoad getItemsToLoad(@NonNull final PlayQueue playQueue,
+                                              final int windowSize) {
+        // The current item has higher priority
+        final int currentIndex = playQueue.getIndex();
+        final PlayQueueItem currentItem = playQueue.getItem(currentIndex);
+        if (currentItem == null) return null;
 
-    /**
+        // The rest are just for seamless playback
-     * Places a {@link MediaSource} into the {@link DynamicConcatenatingMediaSource}
+        // Although timeline is not updated prior to the current index, these sources are still
-     * with position in respect to the play queue only if no {@link MediaSource}
+        // loaded into the cache for faster retrieval at a potentially later time.
-     * already exists at the given index.
+        final int leftBound = Math.max(0, currentIndex - windowSize);
-     * */
+        final int rightLimit = currentIndex + windowSize + 1;
-    private synchronized void emplace(final int index, @NonNull final MediaSource source) {
+        final int rightBound = Math.min(playQueue.size(), rightLimit);
-        if (index < sources.getSize()) return;
+        final Set<PlayQueueItem> neighbors = new ArraySet<>(
+                playQueue.getStreams().subList(leftBound,rightBound));
 
-        sources.addMediaSource(index, source);
+        // Do a round robin
+        final int excess = rightLimit - playQueue.size();
+        if (excess >= 0) {
+            neighbors.addAll(playQueue.getStreams().subList(0, Math.min(playQueue.size(), excess)));
+        }
+        neighbors.remove(currentItem);
+
+        return new ItemsToLoad(currentItem, neighbors);
     }
 
-    /**
+    private static class ItemsToLoad {
-     * Removes a {@link MediaSource} from {@link DynamicConcatenatingMediaSource}
+        @NonNull final private PlayQueueItem center;
-     * at the given index. If this index is out of bound, then the removal is ignored.
+        @NonNull final private Collection<PlayQueueItem> neighbors;
-     * */
-    private synchronized void remove(final int index) {
-        if (index < 0 || index > sources.getSize()) return;
 
-        sources.removeMediaSource(index);
+        ItemsToLoad(@NonNull final PlayQueueItem center,
+                    @NonNull final Collection<PlayQueueItem> neighbors) {
+            this.center = center;
+            this.neighbors = neighbors;
         }
-
-    /**
-     * Moves a {@link MediaSource} in {@link DynamicConcatenatingMediaSource}
-     * from the given source index to the target index. If either index is out of bound,
-     * then the call is ignored.
-     * */
-    private synchronized void move(final int source, final int target) {
-        if (source < 0 || target < 0) return;
-        if (source >= sources.getSize() || target >= sources.getSize()) return;
-
-        sources.moveMediaSource(source, target);
-    }
-
-    /**
-     * Updates the {@link MediaSource} in {@link DynamicConcatenatingMediaSource}
-     * at the given index with a given {@link MediaSource}. If the index is out of bound,
-     * then the replacement is ignored.
-     * <br><br>
-     * Not recommended to use on indices LESS THAN the currently playing index, since
-     * this will modify the playback timeline prior to the index and may cause desynchronization
-     * on the playing item between {@link PlayQueue} and {@link DynamicConcatenatingMediaSource}.
-     * */
-    private synchronized void update(final int index, @NonNull final MediaSource source,
-                                     @Nullable final Runnable finalizingAction) {
-        if (index < 0 || index >= sources.getSize()) return;
-
-        sources.addMediaSource(index + 1, source, () ->
-                sources.removeMediaSource(index, finalizingAction));
     }
 }

app/src/main/java/org/schabi/newpipe/player/playback/PlaybackListener.java

@@ -13,13 +13,13 @@ import java.util.List;
 public interface PlaybackListener {
 
     /**
-     * Called to check if the currently playing stream is close to the end of its playback.
+     * Called to check if the currently playing stream is approaching the end of its playback.
-     * Implementation should return true when the current playback position is within
+     * Implementation should return true when the current playback position is progressing within
-     * timeToEndMillis or less until its playback completes or transitions.
+     * timeToEndMillis or less to its playback during.
      *
      * May be called at any time.
      * */
-    boolean isNearPlaybackEdge(final long timeToEndMillis);
+    boolean isApproachingPlaybackEdge(final long timeToEndMillis);
 
     /**
      * Called when the stream at the current queue index is not ready yet.

app/src/main/java/org/schabi/newpipe/settings/AppearanceSettingsFragment.java

@@ -1,17 +1,25 @@
 package org.schabi.newpipe.settings;
 
+import android.content.Intent;
+import android.os.Build;
 import android.os.Bundle;
+import android.provider.Settings;
 import android.support.annotation.Nullable;
 import android.support.v7.preference.Preference;
+import android.util.Log;
 
 import org.schabi.newpipe.R;
 import org.schabi.newpipe.util.Constants;
 
 public class AppearanceSettingsFragment extends BasePreferenceFragment {
+    private final static boolean CAPTIONING_SETTINGS_ACCESSIBLE =
+            Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
+
     /**
      * Theme that was applied when the settings was opened (or recreated after a theme change)
      */
     private String startThemeKey;
+    private String captionSettingsKey;
 
     @Override
     public void onCreate(@Nullable Bundle savedInstanceState) {
@@ -19,6 +27,12 @@ public class AppearanceSettingsFragment extends BasePreferenceFragment {
         String themeKey = getString(R.string.theme_key);
         startThemeKey = defaultPreferences.getString(themeKey, getString(R.string.default_theme_value));
         findPreference(themeKey).setOnPreferenceChangeListener(themePreferenceChange);
+
+        captionSettingsKey = getString(R.string.caption_settings_key);
+        if (!CAPTIONING_SETTINGS_ACCESSIBLE)  {
+            final Preference captionSettings = findPreference(captionSettingsKey);
+            getPreferenceScreen().removePreference(captionSettings);
+        }
     }
 
     @Override
@@ -26,13 +40,23 @@ public class AppearanceSettingsFragment extends BasePreferenceFragment {
         addPreferencesFromResource(R.xml.appearance_settings);
     }
 
+    @Override
+    public boolean onPreferenceTreeClick(Preference preference) {
+        if (preference.getKey().equals(captionSettingsKey) && CAPTIONING_SETTINGS_ACCESSIBLE) {
+            startActivity(new Intent(Settings.ACTION_CAPTIONING_SETTINGS));
+        }
+
+        return super.onPreferenceTreeClick(preference);
+    }
+
     private Preference.OnPreferenceChangeListener themePreferenceChange = new Preference.OnPreferenceChangeListener() {
         @Override
         public boolean onPreferenceChange(Preference preference, Object newValue) {
             defaultPreferences.edit().putBoolean(Constants.KEY_THEME_CHANGE, true).apply();
             defaultPreferences.edit().putString(getString(R.string.theme_key), newValue.toString()).apply();
 
-            if (!newValue.equals(startThemeKey)) { // If it's not the current theme
+            if (!newValue.equals(startThemeKey) && getActivity() != null) {
+                // If it's not the current theme
                 getActivity().recreate();
             }
 

app/src/main/res/drawable/player_controls_bg.xml

@@ -3,5 +3,5 @@
     <gradient
         android:angle="90"
         android:endColor="#00000000"
-        android:startColor="#8c000000"/>
+        android:startColor="@color/video_overlay_color"/>
 </shape>

app/src/main/res/drawable/player_top_controls_bg.xml

@@ -3,5 +3,5 @@
     <gradient
         android:angle="-90"
         android:endColor="#00000000"
-        android:startColor="#8c000000"/>
+        android:startColor="@color/video_overlay_color"/>
 </shape>

app/src/main/res/layout-land/activity_player_queue_control.xml

@@ -304,7 +304,7 @@
             android:paddingLeft="4dp"
             android:paddingRight="4dp"
             android:gravity="center"
-            android:text="@string/duration_live"
+            android:text="@string/duration_live_button"
             android:textAllCaps="true"
             android:textColor="?attr/colorAccent"
             android:maxLength="4"

app/src/main/res/layout/activity_main_player.xml

@@ -129,7 +129,7 @@
         android:id="@+id/playbackControlRoot"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
-        android:background="#64000000"
+        android:background="@color/video_overlay_color"
         android:visibility="gone"
         tools:visibility="visible">
 
@@ -406,7 +406,7 @@
                     android:paddingLeft="4dp"
                     android:paddingRight="4dp"
                     android:gravity="center"
-                    android:text="@string/duration_live"
+                    android:text="@string/duration_live_button"
                     android:textAllCaps="true"
                     android:textColor="@android:color/white"
                     android:maxLength="4"

app/src/main/res/layout/activity_player_queue_control.xml

@@ -154,7 +154,7 @@
             android:paddingLeft="4dp"
             android:paddingRight="4dp"
             android:gravity="center"
-            android:text="@string/duration_live"
+            android:text="@string/duration_live_button"
             android:textAllCaps="true"
             android:textColor="?attr/colorAccent"
             android:maxLength="4"

app/src/main/res/layout/player_popup.xml

@@ -198,7 +198,7 @@
                 android:paddingLeft="4dp"
                 android:paddingRight="4dp"
                 android:gravity="center_vertical"
-                android:text="@string/duration_live"
+                android:text="@string/duration_live_button"
                 android:textAllCaps="true"
                 android:textColor="@android:color/white"
                 android:maxLength="4"

app/src/main/res/values/colors.xml

@@ -40,7 +40,7 @@
     <color name="playlist_stream_count_background_color">#e6000000</color>
     <color name="duration_text_color">#EEFFFFFF</color>
     <color name="playlist_stream_count_text_color">#ffffff</color>
-    <color name="video_overlay_color">#66000000</color>
+    <color name="video_overlay_color">#64000000</color>
 
     <color name="background_notification_color">#323232</color>
     <color name="background_title_color">#ffffff</color>

app/src/main/res/values/settings_keys.xml

@@ -109,23 +109,7 @@
     </string-array>
 
     <!-- Caption Size -->
-    <string name="caption_size_key" translatable="false">caption_size_key</string>
+    <string name="caption_settings_key" translatable="false">caption_settings_key</string>
-    <string name="caption_size_default" translatable="false">@string/normal_caption_size_key</string>
-
-    <string name="smaller_caption_size_key" translatable="false">smaller_caption_size</string>
-    <string name="normal_caption_size_key" translatable="false">normal_caption_size</string>
-    <string name="larger_caption_size_key" translatable="false">larger_caption_size</string>
-
-    <string-array name="caption_size_descriptions_list" translatable="false">
-        <item>@string/smaller_caption_font_size</item>
-        <item>@string/normal_caption_font_size</item>
-        <item>@string/larger_caption_font_size</item>
-    </string-array>
-    <string-array name="caption_size_values_list" translatable="false">
-        <item>@string/smaller_caption_size_key</item>
-        <item>@string/normal_caption_size_key</item>
-        <item>@string/larger_caption_size_key</item>
-    </string-array>
 
     <!-- Content & History -->
     <string name="show_search_suggestions_key" translatable="false">show_search_suggestions</string>

app/src/main/res/values/strings.xml

@@ -119,6 +119,7 @@
     <string name="show_age_restricted_content_title">Show age restricted content</string>
     <string name="video_is_age_restricted">Age Restricted Video. Allowing such material is possible from Settings.</string>
     <string name="duration_live">live</string>
+    <string name="duration_live_button" translatable="false">LIVE</string>
     <string name="downloads">Downloads</string>
     <string name="downloads_title">Downloads</string>
     <string name="error_report_title">Error report</string>
@@ -425,10 +426,10 @@
     <string name="resize_zoom">ZOOM</string>
 
     <string name="caption_auto_generated">Auto-generated</string>
-    <string name="caption_font_size_settings_title">Caption font size</string>
+
-    <string name="smaller_caption_font_size">Smaller font</string>
+    <!-- Caption Settings -->
-    <string name="normal_caption_font_size">Normal font</string>
+    <string name="caption_setting_title">Caption</string>
-    <string name="larger_caption_font_size">Larger font</string>
+    <string name="caption_setting_description">Modify player caption text scale and background styles. Require player restart to take effect.</string>
 
     <!-- Debug Settings -->
     <string name="enable_leak_canary_title">Enable LeakCanary</string>

app/src/main/res/xml/appearance_settings.xml

@@ -22,11 +22,8 @@
         android:title="@string/show_hold_to_append_title"
         android:summary="@string/show_hold_to_append_summary"/>
 
-    <ListPreference
+    <Preference
-        android:defaultValue="@string/caption_size_default"
+        android:key="@string/caption_settings_key"
-        android:entries="@array/caption_size_descriptions_list"
+        android:title="@string/caption_setting_title"
-        android:entryValues="@array/caption_size_values_list"
+        android:summary="@string/caption_setting_description"/>
-        android:key="@string/caption_size_key"
-        android:summary="%s"
-        android:title="@string/caption_font_size_settings_title"/>
 </PreferenceScreen>

build.gradle

@@ -6,7 +6,7 @@ buildscript {
         google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.1.0'
+        classpath 'com.android.tools.build:gradle:3.1.1'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files