Skip over error items in playlist on iOS. Fix positionStream.

darwin/Classes/AudioPlayer.m

@@ -425,6 +425,7 @@
 }
 
 - (void)enqueueFrom:(int)index {
+    int oldIndex = _index;
     _index = index;
 
     // Update the queue while keeping the currently playing item untouched.
@@ -436,13 +437,23 @@
     IndexedPlayerItem *oldItem = _player.currentItem;
     IndexedPlayerItem *existingItem = nil;
     NSArray *oldPlayerItems = [NSArray arrayWithArray:_player.items];
+    // In the first pass, preserve the old and new items.
     for (int i = 0; i < oldPlayerItems.count; i++) {
-        if (oldPlayerItems[i] != _indexedAudioSources[_index].playerItem) {
+        if (oldPlayerItems[i] == _indexedAudioSources[_index].playerItem) {
-            [_player removeItem:oldPlayerItems[i]];
+            // Preserve and tag new item if it is already in the queue.
-        } else {
             existingItem = oldPlayerItems[i];
+        } else if (oldPlayerItems[i] == oldItem) {
+            // Temporarily preserve old item, just to avoid jumping to
+            // intermediate queue positions unnecessarily. We only want to jump
+            // once to _index.
+        } else {
+            [_player removeItem:oldPlayerItems[i]];
         }
     }
+    // In the second pass, remove the old item (if different from new item).
+    if (_index != oldIndex) {
+        [_player removeItem:oldItem];
+    }
 
     /* NSLog(@"inter order: _player.items.count: ", _player.items.count); */
     /* [self dumpQueue]; */
@@ -601,6 +612,7 @@
 }
 
 - (void)onComplete:(NSNotification *)notification {
+    NSLog(@"onComplete");
     if (_loopMode == loopOne) {
         [self seek:kCMTimeZero index:@(_index) completionHandler:^(BOOL finished) {
             // XXX: Not necessary?
@@ -771,11 +783,31 @@
             }
         }
     } else if ([keyPath isEqualToString:@"currentItem"] && _player.currentItem) {
+        if (_player.currentItem.status == AVPlayerItemStatusFailed) {
+            if ([_orderInv[_index] intValue] + 1 < [_order count]) {
+                // account for automatic move to next item
+                _index = [_order[[_orderInv[_index] intValue] + 1] intValue];
+                NSLog(@"advance to next on error: index = %d", _index);
+                [self broadcastPlaybackEvent];
+            } else {
+                NSLog(@"error on last item");
+            }
+            return;
+        } else {
+            int expectedIndex = [self indexForItem:_player.currentItem];
+            if (_index != expectedIndex) {
+                // AVQueuePlayer will sometimes skip over error items without
+                // notifying this observer.
+                NSLog(@"Queue change detected. Adjusting index from %d -> %d", _index, expectedIndex);
+                _index = expectedIndex;
+                [self broadcastPlaybackEvent];
+            }
+        }
         //NSLog(@"currentItem changed. _index=%d", _index);
         _bufferUnconfirmed = YES;
         // If we've skipped or transitioned to a new item and we're not
         // currently in the middle of a seek
-        if (_player.currentItem && CMTIME_IS_INVALID(_seekPos) && _player.currentItem.status == AVPlayerItemStatusReadyToPlay) {
+        if (CMTIME_IS_INVALID(_seekPos) && _player.currentItem.status == AVPlayerItemStatusReadyToPlay) {
             [self updatePosition];
             IndexedAudioSource *source = ((IndexedPlayerItem *)_player.currentItem).audioSource;
             // We should already be at position zero but for
@@ -827,6 +859,7 @@
 }
 
 - (void)sendError:(FlutterError *)flutterError playerItem:(IndexedPlayerItem *)playerItem {
+    NSLog(@"sendError");
     if (_loadResult && playerItem == _player.currentItem) {
         _loadResult(flutterError);
         _loadResult = nil;

example/lib/main.dart

@@ -115,87 +115,7 @@ class _MyAppState extends State<MyApp> {
                   },
                 ),
               ),
-              StreamBuilder<PlayerState>(
+              ControlButtons(_player),
-                stream: _player.playerStateStream,
-                builder: (context, snapshot) {
-                  final playerState = snapshot.data;
-                  final processingState = playerState?.processingState;
-                  final playing = playerState?.playing;
-                  return Row(
-                    mainAxisSize: MainAxisSize.min,
-                    children: [
-                      IconButton(
-                        icon: Icon(Icons.volume_up),
-                        onPressed: () {
-                          _showSliderDialog(
-                            context: context,
-                            title: "Adjust volume",
-                            divisions: 10,
-                            min: 0.0,
-                            max: 1.0,
-                            stream: _player.volumeStream,
-                            onChanged: _player.setVolume,
-                          );
-                        },
-                      ),
-                      IconButton(
-                        icon: Icon(Icons.skip_previous),
-                        onPressed:
-                            _player.hasPrevious ? _player.seekToPrevious : null,
-                      ),
-                      if (processingState == ProcessingState.loading ||
-                          processingState == ProcessingState.buffering)
-                        Container(
-                          margin: EdgeInsets.all(8.0),
-                          width: 64.0,
-                          height: 64.0,
-                          child: CircularProgressIndicator(),
-                        )
-                      else if (playing != true)
-                        IconButton(
-                          icon: Icon(Icons.play_arrow),
-                          iconSize: 64.0,
-                          onPressed: _player.play,
-                        )
-                      else if (processingState != ProcessingState.completed)
-                        IconButton(
-                          icon: Icon(Icons.pause),
-                          iconSize: 64.0,
-                          onPressed: _player.pause,
-                        )
-                      else
-                        IconButton(
-                          icon: Icon(Icons.replay),
-                          iconSize: 64.0,
-                          onPressed: () =>
-                              _player.seek(Duration.zero, index: 0),
-                        ),
-                      IconButton(
-                        icon: Icon(Icons.skip_next),
-                        onPressed: _player.hasNext ? _player.seekToNext : null,
-                      ),
-                      IconButton(
-                        icon: StreamBuilder<double>(
-                            stream: _player.speedStream,
-                            builder: (context, snapshot) => Text(
-                                "${snapshot.data?.toStringAsFixed(1)}x",
-                                style: TextStyle(fontWeight: FontWeight.bold))),
-                        onPressed: () {
-                          _showSliderDialog(
-                            context: context,
-                            title: "Adjust speed",
-                            divisions: 10,
-                            min: 0.5,
-                            max: 1.5,
-                            stream: _player.speedStream,
-                            onChanged: _player.setSpeed,
-                          );
-                        },
-                      ),
-                    ],
-                  );
-                },
-              ),
               StreamBuilder<Duration>(
                 stream: _player.durationStream,
                 builder: (context, snapshot) {
@@ -299,6 +219,102 @@ class _MyAppState extends State<MyApp> {
   }
 }
 
+class ControlButtons extends StatelessWidget {
+  final AudioPlayer player;
+
+  ControlButtons(this.player);
+
+  @override
+  Widget build(BuildContext context) {
+    return Row(
+      mainAxisSize: MainAxisSize.min,
+      children: [
+        IconButton(
+          icon: Icon(Icons.volume_up),
+          onPressed: () {
+            _showSliderDialog(
+              context: context,
+              title: "Adjust volume",
+              divisions: 10,
+              min: 0.0,
+              max: 1.0,
+              stream: player.volumeStream,
+              onChanged: player.setVolume,
+            );
+          },
+        ),
+        StreamBuilder<int>(
+          stream: player.currentIndexStream,
+          builder: (context, snapshot) => IconButton(
+            icon: Icon(Icons.skip_previous),
+            onPressed: player.hasPrevious ? player.seekToPrevious : null,
+          ),
+        ),
+        StreamBuilder<PlayerState>(
+          stream: player.playerStateStream,
+          builder: (context, snapshot) {
+            final playerState = snapshot.data;
+            final processingState = playerState?.processingState;
+            final playing = playerState?.playing;
+            if (processingState == ProcessingState.loading ||
+                processingState == ProcessingState.buffering) {
+              return Container(
+                margin: EdgeInsets.all(8.0),
+                width: 64.0,
+                height: 64.0,
+                child: CircularProgressIndicator(),
+              );
+            } else if (playing != true) {
+              return IconButton(
+                icon: Icon(Icons.play_arrow),
+                iconSize: 64.0,
+                onPressed: player.play,
+              );
+            } else if (processingState != ProcessingState.completed) {
+              return IconButton(
+                icon: Icon(Icons.pause),
+                iconSize: 64.0,
+                onPressed: player.pause,
+              );
+            } else {
+              return IconButton(
+                icon: Icon(Icons.replay),
+                iconSize: 64.0,
+                onPressed: () => player.seek(Duration.zero, index: 0),
+              );
+            }
+          },
+        ),
+        StreamBuilder(
+          stream: player.currentIndexStream,
+          builder: (context, snapshot) => IconButton(
+            icon: Icon(Icons.skip_next),
+            onPressed: player.hasNext ? player.seekToNext : null,
+          ),
+        ),
+        StreamBuilder<double>(
+          stream: player.speedStream,
+          builder: (context, snapshot) => IconButton(
+            icon: Text("${snapshot.data?.toStringAsFixed(1)}x",
+                style: TextStyle(fontWeight: FontWeight.bold)),
+            onPressed: () {
+              _showSliderDialog(
+                context: context,
+                title: "Adjust speed",
+                divisions: 10,
+                min: 0.5,
+                max: 1.5,
+                stream: player.speedStream,
+                onChanged: player.setSpeed,
+              );
+            },
+          ),
+        ),
+      ],
+    );
+  }
+}
+
 class SeekBar extends StatefulWidget {
   final Duration duration;
   final Duration position;

lib/just_audio.dart

@@ -311,15 +311,18 @@ class AudioPlayer {
     StreamController<Duration> controller = StreamController.broadcast();
     Timer currentTimer;
     StreamSubscription durationSubscription;
+    StreamSubscription playbackEventSubscription;
     void yieldPosition(Timer timer) {
       if (controller.isClosed) {
         timer.cancel();
-        durationSubscription.cancel();
+        durationSubscription?.cancel();
+        playbackEventSubscription?.cancel();
         return;
       }
       if (_durationSubject.isClosed) {
         timer.cancel();
-        durationSubscription.cancel();
+        durationSubscription?.cancel();
+        playbackEventSubscription?.cancel();
         controller.close();
         return;
       }
@@ -331,9 +334,10 @@ class AudioPlayer {
       currentTimer.cancel();
       currentTimer = Timer.periodic(step(), yieldPosition);
     });
-    return Rx.combineLatest2<void, void, Duration>(
+    playbackEventSubscription = playbackEventStream.listen((event) {
-            playbackEventStream, controller.stream, (event, period) => position)
+      controller.add(position);
-        .distinct();
+    });
+    return controller.stream.distinct();
   }
 
   /// Convenience method to load audio from a URL with optional headers,