-Fixed deferred media source from releasing reused resources.

-Fixed external play queue to load more than once.
-Fixed wrong item removal due to player error.
-Added new event to indicate error to play queue.
-Changed player error to skip item instead of removing.
-Modified play queue adapter to update changed items only.
-Removed headers from play queue adapter.
-Merged event broadcast on play queue.
-Changed toast on player error.
-Modified remove event to no longer indicate current index status.
-Modified move event to no longer indicate randomization status.
-Added shuffle check to play queue.

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

@@ -36,6 +36,7 @@ import android.support.annotation.Nullable;
 import android.support.v4.app.NotificationCompat;
 import android.util.Log;
 import android.widget.RemoteViews;
+import android.widget.Toast;
 
 import com.google.android.exoplayer2.PlaybackParameters;
 import com.google.android.exoplayer2.Player;
@@ -402,6 +403,7 @@ public final class BackgroundPlayer extends Service {
         @Override
         public void onError(Exception exception) {
             exception.printStackTrace();
+            Toast.makeText(context, "Failed to play this audio", Toast.LENGTH_SHORT).show();
         }
 
         /*//////////////////////////////////////////////////////////////////////////

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

@@ -33,12 +33,12 @@ public class BackgroundPlayerActivity extends AppCompatActivity
 
     private static final String TAG = "BGPlayerActivity";
 
-    private boolean isServiceBound;
+    private boolean serviceBound;
     private ServiceConnection serviceConnection;
 
     private BackgroundPlayer.BasePlayerImpl player;
 
-    private boolean isSeeking;
+    private boolean seeking;
 
     ////////////////////////////////////////////////////////////////////////////
     // Views
@@ -104,9 +104,9 @@ public class BackgroundPlayerActivity extends AppCompatActivity
     @Override
     protected void onStop() {
         super.onStop();
-        if(isServiceBound) {
+        if(serviceBound) {
             unbindService(serviceConnection);
-            isServiceBound = false;
+            serviceBound = false;
         }
     }
 
@@ -119,7 +119,7 @@ public class BackgroundPlayerActivity extends AppCompatActivity
             @Override
             public void onServiceDisconnected(ComponentName name) {
                 Log.d(TAG, "Background player service is disconnected");
-                isServiceBound = false;
+                serviceBound = false;
                 player = null;
                 finish();
             }
@@ -132,7 +132,7 @@ public class BackgroundPlayerActivity extends AppCompatActivity
                 if (player == null) {
                     finish();
                 } else {
-                    isServiceBound = true;
+                    serviceBound = true;
                     buildComponents();
 
                     player.setActivityListener(BackgroundPlayerActivity.this);
@@ -220,13 +220,13 @@ public class BackgroundPlayerActivity extends AppCompatActivity
 
     @Override
     public void onStartTrackingTouch(SeekBar seekBar) {
-        isSeeking = true;
+        seeking = true;
     }
 
     @Override
     public void onStopTrackingTouch(SeekBar seekBar) {
         player.simpleExoPlayer.seekTo(seekBar.getProgress());
-        isSeeking = false;
+        seeking = false;
     }
 
     ////////////////////////////////////////////////////////////////////////////
@@ -284,7 +284,7 @@ public class BackgroundPlayerActivity extends AppCompatActivity
         progressEndTime.setText(Localization.getDurationString(duration / 1000));
 
         // Set current time if not seeking
-        if (!isSeeking) {
+        if (!seeking) {
             progressSeekBar.setProgress(currentProgress);
             progressCurrentTime.setText(Localization.getDurationString(currentProgress / 1000));
         }

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

@@ -664,8 +664,22 @@ public abstract class BasePlayer implements Player.EventListener,
     @Override
     public void onPlayerError(ExoPlaybackException error) {
         if (DEBUG) Log.d(TAG, "onPlayerError() called with: error = [" + error + "]");
-        playQueue.remove(playQueue.getIndex());
+
+        // If the current window is seekable, then the error is produced by transitioning into
+        // bad window, therefore we simply increment the current index.
+        // This is done because ExoPlayer reports the exception before window is
+        // transitioned due to seamless playback.
+        if (!simpleExoPlayer.isCurrentWindowSeekable()) {
+            playQueue.error();
             onError(error);
+        } else {
+            playQueue.offsetIndex(+1);
+        }
+
+        // Player error causes ExoPlayer to go back to IDLE state, which requires resetting
+        // preparing a new media source.
+        playbackManager.reset();
+        playbackManager.load();
     }
 
     @Override

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

@@ -30,27 +30,37 @@ import io.reactivex.schedulers.Schedulers;
 public final class DeferredMediaSource implements MediaSource {
     private final String TAG = "DeferredMediaSource@" + Integer.toHexString(hashCode());
 
-    private int state = -1;
+    /**
-
+     * This state indicates the {@link DeferredMediaSource} has just been initialized or reset.
+     * The source must be prepared and loaded again before playback.
+     * */
     public final static int STATE_INIT = 0;
+    /**
+     * This state indicates the {@link DeferredMediaSource} has been prepared and is ready to load.
+     * */
     public final static int STATE_PREPARED = 1;
+    /**
+     * This state indicates the {@link DeferredMediaSource} has been loaded without errors and
+     * is ready for playback.
+     * */
     public final static int STATE_LOADED = 2;
-    public final static int STATE_DISPOSED = 3;
 
     public interface Callback {
         /**
-         * Player-specific MediaSource resolution from given StreamInfo.
+         * Player-specific {@link com.google.android.exoplayer2.source.MediaSource} resolution
+         * from a given StreamInfo.
          * */
         MediaSource sourceOf(final StreamInfo info);
     }
 
     private PlayQueueItem stream;
     private Callback callback;
+    private int state;
 
     private MediaSource mediaSource;
 
+    /* Custom internal objects */
     private Disposable loader;
-
     private ExoPlayer exoPlayer;
     private Listener listener;
     private Throwable error;
@@ -62,6 +72,17 @@ public final class DeferredMediaSource implements MediaSource {
         this.state = STATE_INIT;
     }
 
+    /**
+     * Returns the current state of the {@link DeferredMediaSource}.
+     *
+     * @see DeferredMediaSource#STATE_INIT
+     * @see DeferredMediaSource#STATE_PREPARED
+     * @see DeferredMediaSource#STATE_LOADED
+     * */
+    public int state() {
+        return state;
+    }
+
     /**
      * Parameters are kept in the class for delayed preparation.
      * */
@@ -72,28 +93,47 @@ public final class DeferredMediaSource implements MediaSource {
         this.state = STATE_PREPARED;
     }
 
-    public int state() {
-        return state;
-    }
-
     /**
      * Externally controlled loading. This method fully prepares the source to be used
-     * like any other native MediaSource.
+     * like any other native {@link com.google.android.exoplayer2.source.MediaSource}.
      *
      * Ideally, this should be called after this source has entered PREPARED state and
      * called once only.
      *
-     * If loading fails here, an error will be propagated out and result in a
+     * If loading fails here, an error will be propagated out and result in an
-     * {@link com.google.android.exoplayer2.ExoPlaybackException}, which is delegated
+     * {@link com.google.android.exoplayer2.ExoPlaybackException ExoPlaybackException}, which is delegated
      * to the player.
      * */
     public synchronized void load() {
-        if (state != STATE_PREPARED || stream == null || loader != null) return;
+        if (stream == null) {
+            Log.e(TAG, "Stream Info missing, media source loading terminated.");
+            return;
+        }
+        if (state != STATE_PREPARED || loader != null) return;
+
         Log.d(TAG, "Loading: [" + stream.getTitle() + "] with url: " + stream.getUrl());
 
         final Consumer<StreamInfo> onSuccess = new Consumer<StreamInfo>() {
             @Override
             public void accept(StreamInfo streamInfo) throws Exception {
+                onStreamInfoReceived(streamInfo);
+            }
+        };
+
+        final Consumer<Throwable> onError = new Consumer<Throwable>() {
+            @Override
+            public void accept(Throwable throwable) throws Exception {
+            onStreamInfoError(throwable);
+            }
+        };
+
+        loader = stream.getStream()
+                .subscribeOn(Schedulers.io())
+                .observeOn(AndroidSchedulers.mainThread())
+                .subscribe(onSuccess, onError);
+    }
+
+    private void onStreamInfoReceived(final StreamInfo streamInfo) {
         Log.d(TAG, " Loaded: [" + stream.getTitle() + "] with url: " + stream.getUrl());
         state = STATE_LOADED;
 
@@ -112,23 +152,19 @@ public final class DeferredMediaSource implements MediaSource {
 
         mediaSource.prepareSource(exoPlayer, false, listener);
     }
-        };
 
-        final Consumer<Throwable> onError = new Consumer<Throwable>() {
+    private void onStreamInfoError(final Throwable throwable) {
-            @Override
-            public void accept(Throwable throwable) throws Exception {
         Log.e(TAG, "Loading error:", throwable);
         error = throwable;
         state = STATE_LOADED;
     }
-        };
-
-        loader = stream.getStream()
-                .subscribeOn(Schedulers.io())
-                .observeOn(AndroidSchedulers.mainThread())
-                .subscribe(onSuccess, onError);
-    }
 
+    /**
+     * Delegate all errors to the player after {@link #load() load} is complete.
+     *
+     * Specifically, this method is called after an exception has occurred during loading or
+     * {@link com.google.android.exoplayer2.source.MediaSource#prepareSource(ExoPlayer, boolean, Listener) prepareSource}.
+     * */
     @Override
     public void maybeThrowSourceInfoRefreshError() throws IOException {
         if (error != null) {
@@ -145,19 +181,27 @@ public final class DeferredMediaSource implements MediaSource {
         return mediaSource.createPeriod(mediaPeriodId, allocator);
     }
 
+    /**
+     * Releases the media period (buffers).
+     *
+     * This may be called after {@link #releaseSource releaseSource}.
+     * */
     @Override
     public void releasePeriod(MediaPeriod mediaPeriod) {
-        if (mediaSource == null) {
-            Log.e(TAG, "releasePeriod() called when media source is null, memory leak may have occurred.");
-        } else {
         mediaSource.releasePeriod(mediaPeriod);
     }
-    }
 
+    /**
+     * Cleans up all internal custom objects creating during loading.
+     *
+     * This method is called when the parent {@link com.google.android.exoplayer2.source.MediaSource}
+     * is released or when the player is stopped.
+     *
+     * This method should not release or set null the resources passed in through the constructor.
+     * This method should not set null the internal {@link com.google.android.exoplayer2.source.MediaSource}.
+     * */
     @Override
     public void releaseSource() {
-        state = STATE_DISPOSED;
-
         if (mediaSource != null) {
             mediaSource.releaseSource();
         }
@@ -166,9 +210,11 @@ public final class DeferredMediaSource implements MediaSource {
         }
 
         /* Do not set mediaSource as null here as it may be called through releasePeriod */
-        stream = null;
+        loader = null;
-        callback = null;
         exoPlayer = null;
         listener = null;
+        error = null;
+
+        state = STATE_INIT;
     }
 }

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

@@ -107,11 +107,13 @@ public class MediaSourceManager implements DeferredMediaSource.Callback {
 
     /**
      * Loads the current playing stream and the streams within its WINDOW_SIZE bound.
+     *
+     * Unblocks the player once the item at the current index is loaded.
      * */
     public void load() {
         // The current item has higher priority
         final int currentIndex = playQueue.getIndex();
-        final PlayQueueItem currentItem = playQueue.get(currentIndex);
+        final PlayQueueItem currentItem = playQueue.getItem(currentIndex);
         if (currentItem == null) return;
         load(currentItem);
 
@@ -121,12 +123,24 @@ public class MediaSourceManager implements DeferredMediaSource.Callback {
         final int rightBound = Math.min(playQueue.size(), rightLimit);
         final List<PlayQueueItem> items = new ArrayList<>(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)));
 
         for (final PlayQueueItem item: items) load(item);
     }
 
+    /**
+     * Blocks the player and repopulate the sources.
+     *
+     * Does not ensure the player is unblocked and should be done explicitly through {@link #load() load}.
+     * */
+    public void reset() {
+        tryBlock();
+        resetSources();
+        populateSources();
+    }
+
     /*//////////////////////////////////////////////////////////////////////////
     // Event Reactor
     //////////////////////////////////////////////////////////////////////////*/
@@ -141,7 +155,19 @@ public class MediaSourceManager implements DeferredMediaSource.Callback {
             }
 
             @Override
-            public void onNext(@NonNull PlayQueueMessage event) {
+            public void onNext(@NonNull PlayQueueMessage playQueueMessage) {
+                onPlayQueueChanged(playQueueMessage);
+            }
+
+            @Override
+            public void onError(@NonNull Throwable e) {}
+
+            @Override
+            public void onComplete() {}
+        };
+    }
+
+    private void onPlayQueueChanged(final PlayQueueMessage event) {
         // why no pattern matching in Java =(
         switch (event.type()) {
             case APPEND:
@@ -150,21 +176,20 @@ public class MediaSourceManager implements DeferredMediaSource.Callback {
             case SELECT:
                 if (isCurrentIndexLoaded()) {
                     sync();
+                } else {
+                    reset();
                 }
                 break;
             case REMOVE:
                 final RemoveEvent removeEvent = (RemoveEvent) event;
-                        if (!removeEvent.isCurrent()) {
                 remove(removeEvent.index());
                 break;
-                        }
-                        // Reset the sources if the index to remove is the current playing index
             case INIT:
             case REORDER:
-                        tryBlock();
+                reset();
-                        resetSources();
-                        populateSources();
                 break;
+            case ERROR:
+            case MOVE:
             default:
                 break;
         }
@@ -181,14 +206,6 @@ public class MediaSourceManager implements DeferredMediaSource.Callback {
         if (playQueueReactor != null) playQueueReactor.request(1);
     }
 
-            @Override
-            public void onError(@NonNull Throwable e) {}
-
-            @Override
-            public void onComplete() {}
-        };
-    }
-
     /*//////////////////////////////////////////////////////////////////////////
     // Internal Helpers
     //////////////////////////////////////////////////////////////////////////*/
@@ -220,7 +237,7 @@ public class MediaSourceManager implements DeferredMediaSource.Callback {
     }
 
     private void sync() {
-        final PlayQueueItem currentItem = playQueue.getCurrent();
+        final PlayQueueItem currentItem = playQueue.getItem();
 
         final Consumer<StreamInfo> syncPlayback = new Consumer<StreamInfo>() {
             @Override

app/src/main/java/org/schabi/newpipe/playlist/ExternalPlayQueue.java

@@ -20,8 +20,6 @@ import io.reactivex.schedulers.Schedulers;
 public final class ExternalPlayQueue extends PlayQueue {
     private final String TAG = "ExternalPlayQueue@" + Integer.toHexString(hashCode());
 
-    private static final int RETRY_COUNT = 2;
-
     private boolean isComplete;
 
     private int serviceId;
@@ -54,7 +52,6 @@ public final class ExternalPlayQueue extends PlayQueue {
        ExtractorHelper.getMorePlaylistItems(this.serviceId, this.baseUrl, this.nextUrl)
                 .subscribeOn(Schedulers.io())
                 .observeOn(AndroidSchedulers.mainThread())
-                .retry(RETRY_COUNT)
                 .subscribe(getPlaylistObserver());
     }
 
@@ -75,6 +72,9 @@ public final class ExternalPlayQueue extends PlayQueue {
                 nextUrl = result.nextItemsUrl;
 
                 append(extractPlaylistItems(result.nextItemsList));
+
+                fetchReactor.dispose();
+                fetchReactor = null;
             }
 
             @Override

app/src/main/java/org/schabi/newpipe/playlist/PlayQueue.java

@@ -6,6 +6,7 @@ import android.util.Log;
 import org.reactivestreams.Subscriber;
 import org.reactivestreams.Subscription;
 import org.schabi.newpipe.playlist.events.AppendEvent;
+import org.schabi.newpipe.playlist.events.ErrorEvent;
 import org.schabi.newpipe.playlist.events.InitEvent;
 import org.schabi.newpipe.playlist.events.PlayQueueMessage;
 import org.schabi.newpipe.playlist.events.RemoveEvent;
@@ -44,8 +45,7 @@ public abstract class PlayQueue implements Serializable {
     private ArrayList<PlayQueueItem> streams;
     private final AtomicInteger queueIndex;
 
-    private transient BehaviorSubject<PlayQueueMessage> streamsEventBroadcast;
+    private transient BehaviorSubject<PlayQueueMessage> eventBroadcast;
-    private transient BehaviorSubject<PlayQueueMessage> indexEventBroadcast;
     private transient Flowable<PlayQueueMessage> broadcastReceiver;
     private transient Subscription reportingReactor;
 
@@ -70,13 +70,11 @@ public abstract class PlayQueue implements Serializable {
      * Also starts a self reporter for logging if debug mode is enabled.
      * */
     public void init() {
-        streamsEventBroadcast = BehaviorSubject.create();
+        eventBroadcast = BehaviorSubject.create();
-        indexEventBroadcast = BehaviorSubject.create();
 
-        broadcastReceiver = Flowable.merge(
+        broadcastReceiver = eventBroadcast.toFlowable(BackpressureStrategy.BUFFER)
-                streamsEventBroadcast.toFlowable(BackpressureStrategy.BUFFER),
+                .observeOn(AndroidSchedulers.mainThread())
-                indexEventBroadcast.toFlowable(BackpressureStrategy.BUFFER)
+                .startWith(new InitEvent());
-        ).observeOn(AndroidSchedulers.mainThread()).startWith(new InitEvent());
 
         if (DEBUG) broadcastReceiver.subscribe(getSelfReporter());
     }
@@ -88,8 +86,7 @@ public abstract class PlayQueue implements Serializable {
         if (backup != null) backup.clear();
         if (streams != null) streams.clear();
 
-        if (streamsEventBroadcast != null) streamsEventBroadcast.onComplete();
+        if (eventBroadcast != null) eventBroadcast.onComplete();
-        if (indexEventBroadcast != null) indexEventBroadcast.onComplete();
         if (reportingReactor != null) reportingReactor.cancel();
 
         broadcastReceiver = null;
@@ -123,15 +120,15 @@ public abstract class PlayQueue implements Serializable {
     /**
      * Returns the current item that should be played.
      * */
-    public PlayQueueItem getCurrent() {
+    public PlayQueueItem getItem() {
-        return get(getIndex());
+        return getItem(getIndex());
     }
 
     /**
      * Returns the item at the given index.
      * May throw {@link IndexOutOfBoundsException}.
      * */
-    public PlayQueueItem get(int index) {
+    public PlayQueueItem getItem(int index) {
         if (index >= streams.size() || streams.get(index) == null) return null;
         return streams.get(index);
     }
@@ -160,6 +157,13 @@ public abstract class PlayQueue implements Serializable {
         return streams.isEmpty();
     }
 
+    /**
+     * Determines if the current play queue is shuffled.
+     * */
+    public boolean isShuffled() {
+        return backup != null;
+    }
+
     /**
      * Returns an immutable view of the play queue.
      * */
@@ -191,12 +195,14 @@ public abstract class PlayQueue implements Serializable {
     public synchronized void setIndex(final int index) {
         if (index == getIndex()) return;
 
+        final int oldIndex = getIndex();
+
         int newIndex = index;
         if (index < 0) newIndex = 0;
         if (index >= streams.size()) newIndex = isComplete() ? index % streams.size() : streams.size() - 1;
 
         queueIndex.set(newIndex);
-        indexEventBroadcast.onNext(new SelectEvent(newIndex));
+        broadcast(new SelectEvent(oldIndex, newIndex));
     }
 
     /**
@@ -213,7 +219,7 @@ public abstract class PlayQueue implements Serializable {
      *
      * Will emit a {@link AppendEvent} on any given context.
      * */
-    protected synchronized void append(final PlayQueueItem... items) {
+    public synchronized void append(final PlayQueueItem... items) {
         streams.addAll(Arrays.asList(items));
         broadcast(new AppendEvent(items.length));
     }
@@ -223,7 +229,7 @@ public abstract class PlayQueue implements Serializable {
      *
      * Will emit a {@link AppendEvent} on any given context.
      * */
-    protected synchronized void append(final Collection<PlayQueueItem> items) {
+    public synchronized void append(final Collection<PlayQueueItem> items) {
         streams.addAll(items);
         broadcast(new AppendEvent(items.size()));
     }
@@ -235,22 +241,35 @@ public abstract class PlayQueue implements Serializable {
      * On cases where the current playing index exceeds the playlist range, it is set to 0.
      *
      * Will emit a {@link RemoveEvent} if the index is within the play queue index range.
-     *
      * */
     public synchronized void remove(final int index) {
         if (index >= streams.size() || index < 0) return;
+        removeInternal(index);
+        broadcast(new RemoveEvent(index));
+    }
 
+    /**
+     * Report an exception for the item at the current index in order to remove it.
+     *
+     * This is done as a separate event as the underlying manager may have
+     * different implementation regarding exceptions.
+     * */
+    public synchronized void error() {
+        final int index = getIndex();
+        removeInternal(index);
+        broadcast(new ErrorEvent(index));
+    }
+
+    private synchronized void removeInternal(final int index) {
         final int currentIndex = queueIndex.get();
-        final boolean isCurrent = index == getIndex();
 
         if (currentIndex > index) {
             queueIndex.decrementAndGet();
         } else if (currentIndex >= size()) {
             queueIndex.set(0);
         }
-        streams.remove(index);
 
-        broadcast(new RemoveEvent(index, isCurrent));
+        streams.remove(index);
     }
 
     /**
@@ -264,11 +283,11 @@ public abstract class PlayQueue implements Serializable {
      * */
     public synchronized void shuffle() {
         backup = new ArrayList<>(streams);
-        final PlayQueueItem current = getCurrent();
+        final PlayQueueItem current = getItem();
         Collections.shuffle(streams);
         queueIndex.set(streams.indexOf(current));
 
-        broadcast(new ReorderEvent(true));
+        broadcast(new ReorderEvent());
     }
 
     /**
@@ -280,12 +299,13 @@ public abstract class PlayQueue implements Serializable {
      * */
     public synchronized void unshuffle() {
         if (backup == null) return;
-        final PlayQueueItem current = getCurrent();
+        final PlayQueueItem current = getItem();
         streams.clear();
         streams = backup;
+        backup = null;
         queueIndex.set(streams.indexOf(current));
 
-        broadcast(new ReorderEvent(false));
+        broadcast(new ReorderEvent());
     }
 
     /*//////////////////////////////////////////////////////////////////////////
@@ -293,7 +313,9 @@ public abstract class PlayQueue implements Serializable {
     //////////////////////////////////////////////////////////////////////////*/
 
     private void broadcast(final PlayQueueMessage event) {
-        streamsEventBroadcast.onNext(event);
+        if (eventBroadcast != null) {
+            eventBroadcast.onNext(event);
+        }
     }
 
     private Subscriber<PlayQueueMessage> getSelfReporter() {

app/src/main/java/org/schabi/newpipe/playlist/PlayQueueAdapter.java

@@ -7,7 +7,11 @@ import android.view.View;
 import android.view.ViewGroup;
 
 import org.schabi.newpipe.R;
+import org.schabi.newpipe.playlist.events.AppendEvent;
+import org.schabi.newpipe.playlist.events.ErrorEvent;
 import org.schabi.newpipe.playlist.events.PlayQueueMessage;
+import org.schabi.newpipe.playlist.events.RemoveEvent;
+import org.schabi.newpipe.playlist.events.SelectEvent;
 
 import java.util.List;
 
@@ -38,10 +42,12 @@ import io.reactivex.disposables.Disposable;
 public class PlayQueueAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
     private static final String TAG = PlayQueueAdapter.class.toString();
 
+    private static final int ITEM_VIEW_TYPE_ID = 0;
+    private static final int FOOTER_VIEW_TYPE_ID = 1;
+
     private final PlayQueueItemBuilder playQueueItemBuilder;
     private final PlayQueue playQueue;
     private boolean showFooter = false;
-    private View header = null;
     private View footer = null;
 
     private Disposable playQueueReactor;
@@ -54,11 +60,6 @@ public class PlayQueueAdapter extends RecyclerView.Adapter<RecyclerView.ViewHold
         public View view;
     }
 
-    public void showFooter(final boolean show) {
-        showFooter = show;
-        notifyDataSetChanged();
-    }
-
     public PlayQueueAdapter(final PlayQueue playQueue) {
         this.playQueueItemBuilder = new PlayQueueItemBuilder();
         this.playQueue = playQueue;
@@ -92,7 +93,7 @@ public class PlayQueueAdapter extends RecyclerView.Adapter<RecyclerView.ViewHold
 
             @Override
             public void onNext(@NonNull PlayQueueMessage playQueueMessage) {
-                notifyDataSetChanged();
+                onPlayQueueChanged(playQueueMessage);
             }
 
             @Override
@@ -109,19 +110,46 @@ public class PlayQueueAdapter extends RecyclerView.Adapter<RecyclerView.ViewHold
                 .subscribe(observer);
     }
 
+    private void onPlayQueueChanged(final PlayQueueMessage message) {
+        switch (message.type()) {
+            case SELECT:
+                final SelectEvent selectEvent = (SelectEvent) message;
+                notifyItemChanged(selectEvent.getOldIndex());
+                notifyItemChanged(selectEvent.getNewIndex());
+                break;
+            case APPEND:
+                final AppendEvent appendEvent = (AppendEvent) message;
+                notifyItemRangeInserted(playQueue.size(), appendEvent.getAmount());
+                break;
+            case ERROR:
+                final ErrorEvent errorEvent = (ErrorEvent) message;
+                notifyItemRangeRemoved(errorEvent.index(), 1);
+                notifyItemChanged(errorEvent.index());
+                break;
+            case REMOVE:
+                final RemoveEvent removeEvent = (RemoveEvent) message;
+                notifyItemRangeRemoved(removeEvent.index(), 1);
+                notifyItemChanged(removeEvent.index());
+                break;
+            default:
+                notifyDataSetChanged();
+                break;
+        }
+    }
+
     public void dispose() {
         if (playQueueReactor != null) playQueueReactor.dispose();
         playQueueReactor = null;
     }
 
-    public void setHeader(View header) {
-        this.header = header;
-        notifyDataSetChanged();
-    }
-
     public void setFooter(View footer) {
         this.footer = footer;
-        notifyDataSetChanged();
+        notifyItemChanged(playQueue.size());
+    }
+
+    public void showFooter(final boolean show) {
+        showFooter = show;
+        notifyItemChanged(playQueue.size());
     }
 
     public List<PlayQueueItem> getItems() {
@@ -131,36 +159,28 @@ public class PlayQueueAdapter extends RecyclerView.Adapter<RecyclerView.ViewHold
     @Override
     public int getItemCount() {
         int count = playQueue.getStreams().size();
-        if(header != null) count++;
         if(footer != null && showFooter) count++;
         return count;
     }
 
     @Override
     public int getItemViewType(int position) {
-        if(header != null && position == 0) {
-            return 0;
-        } else if(header != null) {
-            position--;
-        }
         if(footer != null && position == playQueue.getStreams().size() && showFooter) {
-            return 1;
+            return FOOTER_VIEW_TYPE_ID;
         }
-        return 2;
+
+        return ITEM_VIEW_TYPE_ID;
     }
 
     @Override
     public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int type) {
         switch(type) {
-            case 0:
+            case FOOTER_VIEW_TYPE_ID:
-                return new HFHolder(header);
-            case 1:
                 return new HFHolder(footer);
-            case 2:
+            case ITEM_VIEW_TYPE_ID:
-                return new PlayQueueItemHolder(LayoutInflater.from(parent.getContext())
+                return new PlayQueueItemHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.play_queue_item, parent, false));
-                        .inflate(R.layout.play_queue_item, parent, false));
             default:
-                Log.e(TAG, "Trollolo");
+                Log.e(TAG, "Attempting to create view holder with undefined type: " + type);
                 return null;
         }
     }
@@ -168,14 +188,10 @@ public class PlayQueueAdapter extends RecyclerView.Adapter<RecyclerView.ViewHold
     @Override
     public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
         if(holder instanceof PlayQueueItemHolder) {
-            // Ensure header does not interfere with list building
-            if (header != null) position--;
             // Build the list item
             playQueueItemBuilder.buildStreamInfoItem((PlayQueueItemHolder) holder, playQueue.getStreams().get(position));
             // Check if the current item should be selected/highlighted
             holder.itemView.setSelected(playQueue.getIndex() == position);
-        } else if(holder instanceof HFHolder && position == 0 && header != null) {
-            ((HFHolder) holder).view = header;
         } else if(holder instanceof HFHolder && position == playQueue.getStreams().size() && footer != null && showFooter) {
             ((HFHolder) holder).view = footer;
         }

app/src/main/java/org/schabi/newpipe/playlist/events/ErrorEvent.java

@@ -0,0 +1,19 @@
+package org.schabi.newpipe.playlist.events;
+
+
+public class ErrorEvent implements PlayQueueMessage {
+    final private int index;
+
+    @Override
+    public PlayQueueEvent type() {
+        return PlayQueueEvent.ERROR;
+    }
+
+    public ErrorEvent(final int index) {
+        this.index = index;
+    }
+
+    public int index() {
+        return index;
+    }
+}

app/src/main/java/org/schabi/newpipe/playlist/events/PlayQueueEvent.java

@@ -15,7 +15,10 @@ public enum PlayQueueEvent {
     // sent when two streams swap place in the play queue
     MOVE,
 
-    // send when queue is shuffled
+    // sent when queue is shuffled
-    REORDER
+    REORDER,
+
+    // sent when the item at index has caused an exception
+    ERROR
 }
 

app/src/main/java/org/schabi/newpipe/playlist/events/RemoveEvent.java

@@ -3,23 +3,17 @@ package org.schabi.newpipe.playlist.events;
 
 public class RemoveEvent implements PlayQueueMessage {
     final private int index;
-    final private boolean isCurrent;
 
     @Override
     public PlayQueueEvent type() {
         return PlayQueueEvent.REMOVE;
     }
 
-    public RemoveEvent(final int index, final boolean isCurrent) {
+    public RemoveEvent(final int index) {
         this.index = index;
-        this.isCurrent = isCurrent;
     }
 
     public int index() {
         return index;
     }
-
-    public boolean isCurrent() {
-        return isCurrent;
-    }
 }

app/src/main/java/org/schabi/newpipe/playlist/events/ReorderEvent.java

@@ -1,18 +1,12 @@
 package org.schabi.newpipe.playlist.events;
 
 public class ReorderEvent implements PlayQueueMessage {
-    final private boolean randomize;
-
     @Override
     public PlayQueueEvent type() {
         return PlayQueueEvent.REORDER;
     }
 
-    public ReorderEvent(final boolean randomize) {
+    public ReorderEvent() {
-        this.randomize = randomize;
-    }
 
-    public boolean isRandomize() {
-        return randomize;
     }
 }

app/src/main/java/org/schabi/newpipe/playlist/events/SelectEvent.java

@@ -2,6 +2,7 @@ package org.schabi.newpipe.playlist.events;
 
 
 public class SelectEvent implements PlayQueueMessage {
+    final private int oldIndex;
     final private int newIndex;
 
     @Override
@@ -9,11 +10,16 @@ public class SelectEvent implements PlayQueueMessage {
         return PlayQueueEvent.SELECT;
     }
 
-    public SelectEvent(final int newIndex) {
+    public SelectEvent(final int oldIndex, final int newIndex) {
+        this.oldIndex = oldIndex;
         this.newIndex = newIndex;
     }
 
-    public int index() {
+    public int getOldIndex() {
+        return oldIndex;
+    }
+
+    public int getNewIndex() {
         return newIndex;
     }
 }