Separate buffering from playbackState. Improve Android buffering detection.

android/src/main/java/com/ryanheise/just_audio/AudioPlayer.java

@@ -35,23 +35,9 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener {
 	private final MethodChannel methodChannel;
 	private final EventChannel eventChannel;
 	private EventSink eventSink;
-	private final Handler handler = new Handler();
-	private final Runnable positionObserver = new Runnable() {
-		@Override
-		public void run() {
-			if (state != PlaybackState.playing && state != PlaybackState.buffering)
-				return;
-
-			if (eventSink != null) {
-				checkForDiscontinuity();
-			}
-			handler.postDelayed(this, 200);
-		}
-	};
 
 	private final String id;
 	private volatile PlaybackState state;
-	private PlaybackState stateBeforeSeek;
 	private long updateTime;
 	private long updatePosition;
 
@@ -64,6 +50,7 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener {
 	private Result prepareResult;
 	private Result seekResult;
 	private boolean seekProcessed;
+	private boolean buffering;
 	private MediaSource mediaSource;
 
 	private SimpleExoPlayer player;
@@ -106,15 +93,19 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener {
 				completeSeek();
 			}
 			break;
-		case Player.STATE_BUFFERING:
-			// TODO: use this instead of checkForDiscontinuity.
-			break;
 		case Player.STATE_ENDED:
 			if (state != PlaybackState.completed) {
 				transition(PlaybackState.completed);
 			}
 			break;
 		}
+		final boolean buffering = playbackState == Player.STATE_BUFFERING;
+		// don't notify buffering if (buffering && state == stopped)
+		final boolean notifyBuffering = !buffering || state != PlaybackState.stopped;
+		if (notifyBuffering && (buffering != this.buffering)) {
+			this.buffering = buffering;
+			broadcastPlaybackEvent();
+		}
 	}
 
 	@Override
@@ -130,29 +121,10 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener {
 	private void completeSeek() {
 		seekProcessed = false;
 		seekPos = null;
-		transition(stateBeforeSeek);
 		seekResult.success(null);
-		stateBeforeSeek = null;
 		seekResult = null;
 	}
 
-	private void checkForDiscontinuity() {
-		final long now = System.currentTimeMillis();
-		final long position = getCurrentPosition();
-		final long timeSinceLastUpdate = now - updateTime;
-		final long expectedPosition = updatePosition + (long)(timeSinceLastUpdate * speed);
-		final long drift = position - expectedPosition;
-		// Update if we've drifted or just started observing
-		if (updateTime == 0L) {
-			broadcastPlaybackEvent();
-		} else if (drift < -100) {
-			System.out.println("time discontinuity detected: " + drift);
-			transition(PlaybackState.buffering);
-		} else if (state == PlaybackState.buffering) {
-			transition(PlaybackState.playing);
-		}
-	}
-
 	@Override
 	public void onMethodCall(final MethodCall call, final Result result) {
 		final List<?> args = (List<?>)call.arguments;
@@ -219,6 +191,7 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener {
 	private void broadcastPlaybackEvent() {
 		final ArrayList<Object> event = new ArrayList<Object>();
 		event.add(state.ordinal());
+		event.add(buffering);
 		event.add(updatePosition = getCurrentPosition());
 		event.add(updateTime = System.currentTimeMillis());
 		eventSink.success(event);
@@ -237,9 +210,6 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener {
 	private void transition(final PlaybackState newState) {
 		final PlaybackState oldState = state;
 		state = newState;
-		if (oldState != PlaybackState.playing && newState == PlaybackState.playing) {
-			startObservingPosition();
-		}
 		broadcastPlaybackEvent();
 	}
 
@@ -282,14 +252,9 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener {
 			break;
 		case stopped:
 		case completed:
-		case buffering:
 		case paused:
-			player.setPlayWhenReady(true);
-			if (seekResult != null) {
-				stateBeforeSeek = PlaybackState.playing;
-			} else {
 			transition(PlaybackState.playing);
-			}
+			player.setPlayWhenReady(true);
 			break;
 		default:
 			throw new IllegalStateException("Cannot call play from connecting/none states (" + state + ")");
@@ -301,12 +266,8 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener {
 		case paused:
 			break;
 		case playing:
-		case buffering:
 			player.setPlayWhenReady(false);
 			transition(PlaybackState.paused);
-			if (seekResult != null) {
-				stateBeforeSeek = PlaybackState.paused;
-			}
 			break;
 		default:
 			throw new IllegalStateException("Can call pause only from playing and buffering states (" + state + ")");
@@ -320,18 +281,17 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener {
 			break;
 		case connecting:
 			abortExistingConnection();
+			buffering = false;
 			transition(PlaybackState.stopped);
 			result.success(null);
 			break;
-		case buffering:
-			abortSeek();
-			// no break
 		case completed:
 		case playing:
 		case paused:
+			abortSeek();
 			player.setPlayWhenReady(false);
-			player.seekTo(0L);
 			transition(PlaybackState.stopped);
+			player.seekTo(0L);
 			result.success(null);
 			break;
 		default:
@@ -358,11 +318,6 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener {
 		seekPos = position;
 		seekResult = result;
 		seekProcessed = false;
-		if (stateBeforeSeek == null) {
-			stateBeforeSeek = state;
-		}
-		handler.removeCallbacks(positionObserver);
-		transition(PlaybackState.buffering);
 		player.seekTo(position);
 	}
 
@@ -376,7 +331,6 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener {
 			seekResult.success(null);
 			seekResult = null;
 			seekPos = null;
-			stateBeforeSeek = null;
 			seekProcessed = false;
 		}
 	}
@@ -388,17 +342,11 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener {
 		}
 	}
 
-	private void startObservingPosition() {
-		handler.removeCallbacks(positionObserver);
-		handler.post(positionObserver);
-	}
-
 	enum PlaybackState {
 		none,
 		stopped,
 		paused,
 		playing,
-		buffering,
 		connecting,
 		completed
 	}

example/lib/main.dart

@@ -43,27 +43,29 @@ class _MyAppState extends State<MyApp> {
             children: [
               Text("Science Friday"),
               Text("Science Friday and WNYC Studios"),
-              StreamBuilder<AudioPlaybackState>(
+              StreamBuilder<FullAudioPlaybackState>(
-                stream: _player.playbackStateStream,
+                stream: _player.fullPlaybackStateStream,
                 builder: (context, snapshot) {
-                  final state = snapshot.data;
+                  final fullState = snapshot.data;
+                  final state = fullState?.state;
+                  final buffering = fullState?.buffering;
                   return Row(
                     mainAxisSize: MainAxisSize.min,
                     children: [
-                      if (state == AudioPlaybackState.playing)
+                      if (state == AudioPlaybackState.connecting ||
-                        IconButton(
+                          buffering == true)
-                          icon: Icon(Icons.pause),
-                          iconSize: 64.0,
-                          onPressed: _player.pause,
-                        )
-                      else if (state == AudioPlaybackState.buffering ||
-                          state == AudioPlaybackState.connecting)
                         Container(
                           margin: EdgeInsets.all(8.0),
                           width: 64.0,
                           height: 64.0,
                           child: CircularProgressIndicator(),
                         )
+                      else if (state == AudioPlaybackState.playing)
+                        IconButton(
+                          icon: Icon(Icons.pause),
+                          iconSize: 64.0,
+                          onPressed: _player.pause,
+                        )
                       else
                         IconButton(
                           icon: Icon(Icons.play_arrow),

ios/Classes/AudioPlayer.h

@@ -11,7 +11,6 @@ enum PlaybackState {
 	stopped,
 	paused,
 	playing,
-	buffering,
 	connecting,
 	completed
 };

ios/Classes/AudioPlayer.m

@@ -10,11 +10,11 @@
 	NSString* _playerId;
 	AVPlayer* _player;
 	enum PlaybackState _state;
-	enum PlaybackState _stateBeforeSeek;
 	long long _updateTime;
 	int _updatePosition;
 	int _seekPos;
 	FlutterResult _connectionResult;
+	BOOL _buffering;
 	id _endObserver;
 	id _timeObserver;
 }
@@ -32,9 +32,9 @@
 		     binaryMessenger:[registrar messenger]];
 	[_eventChannel setStreamHandler:self];
 	_state = none;
-	_stateBeforeSeek = none;
 	_player = nil;
 	_seekPos = -1;
+	_buffering = NO;
 	_endObserver = 0;
 	_timeObserver = 0;
 	__weak __typeof__(self) weakSelf = self;
@@ -94,7 +94,7 @@
 
 - (void)checkForDiscontinuity {
 	if (!_eventSink) return;
-	if (_state != playing && _state != buffering) return;
+	if ((_state != playing) && !_buffering) return;
 	long long now = (long long)([[NSDate date] timeIntervalSince1970] * 1000.0);
 	int position = [self getCurrentPosition];
 	long long timeSinceLastUpdate = now - _updateTime;
@@ -105,9 +105,11 @@
 		[self broadcastPlaybackEvent];
 	} else if (drift < -100) {
 		NSLog(@"time discontinuity detected: %lld", drift);
-		[self setPlaybackState:buffering];
+		_buffering = YES;
-	} else if (_state == buffering) {
+		[self broadcastPlaybackEvent];
-		[self setPlaybackState:playing];
+	} else if (_buffering) {
+		_buffering = NO;
+		[self broadcastPlaybackEvent];
 	}
 }
 
@@ -118,6 +120,8 @@
 	_eventSink(@[
 		// state
 		@(_state),
+		// buffering
+		@(_buffering),
 		// updatePosition
 		@(_updatePosition),
 		// updateTime
@@ -292,10 +296,10 @@
 }
 
 - (void)seek:(int)position result:(FlutterResult)result {
-	_stateBeforeSeek = _state;
 	_seekPos = position;
 	NSLog(@"seek. enter buffering");
-	[self setPlaybackState:buffering];
+	_buffering = YES;
+	[self broadcastPlaybackEvent];
 	[_player seekToTime:CMTimeMake(position, 1000)
 	  completionHandler:^(BOOL finished) {
 		  NSLog(@"seek completed");
@@ -305,8 +309,8 @@
 
 - (void)onSeekCompletion:(FlutterResult)result {
 	_seekPos = -1;
-	[self setPlaybackState:_stateBeforeSeek];
+	_buffering = NO;
-	_stateBeforeSeek = none;
+	[self broadcastPlaybackEvent];
 	result(nil);
 }
 

lib/just_audio.dart

@@ -34,10 +34,7 @@ import 'package:rxdart/rxdart.dart';
 /// * [AudioPlaybackState.stopped]: eventually after [setUrl], [setFilePath],
 /// [setAsset] or [setClip] completes, and immediately after [stop].
 /// * [AudioPlaybackState.paused]: after [pause].
-/// * [AudioPlaybackState.playing]: after [play] and after sufficiently
+/// * [AudioPlaybackState.playing]: after [play].
-/// buffering during normal playback.
-/// * [AudioPlaybackState.buffering]: immediately after a seek request and
-/// during normal playback when the next buffer is not ready to be played.
 /// * [AudioPlaybackState.connecting]: immediately after [setUrl],
 /// [setFilePath] and [setAsset] while waiting for the media to load.
 /// * [AudioPlaybackState.completed]: immediately after playback reaches the
@@ -64,6 +61,7 @@ class AudioPlayer {
   // TODO: also broadcast this event on instantiation.
   AudioPlaybackEvent _audioPlaybackEvent = AudioPlaybackEvent(
     state: AudioPlaybackState.none,
+    buffering: false,
     updatePosition: Duration.zero,
     updateTime: Duration.zero,
     speed: 1.0,
@@ -77,6 +75,10 @@ class AudioPlayer {
 
   final _playbackStateSubject = BehaviorSubject<AudioPlaybackState>();
 
+  final _bufferingSubject = BehaviorSubject<bool>();
+
+  final _fullPlaybackStateSubject = BehaviorSubject<FullAudioPlaybackState>();
+
   double _volume = 1.0;
 
   double _speed = 1.0;
@@ -90,14 +92,22 @@ class AudioPlayer {
         .receiveBroadcastStream()
         .map((data) => _audioPlaybackEvent = AudioPlaybackEvent(
               state: AudioPlaybackState.values[data[0]],
-              updatePosition: Duration(milliseconds: data[1]),
+              buffering: data[1],
-              updateTime: Duration(milliseconds: data[2]),
+              updatePosition: Duration(milliseconds: data[2]),
+              updateTime: Duration(milliseconds: data[3]),
               speed: _speed,
             ));
     _eventChannelStreamSubscription =
         _eventChannelStream.listen(_playbackEventSubject.add);
     _playbackStateSubject
         .addStream(playbackEventStream.map((state) => state.state).distinct());
+    _bufferingSubject.addStream(
+        playbackEventStream.map((state) => state.buffering).distinct());
+    _fullPlaybackStateSubject.addStream(
+        Rx.combineLatest2<AudioPlaybackState, bool, FullAudioPlaybackState>(
+            playbackStateStream,
+            bufferingStream,
+            (state, buffering) => FullAudioPlaybackState(state, buffering)));
   }
 
   /// The duration of any media set via [setUrl], [setFilePath] or [setAsset],
@@ -121,6 +131,16 @@ class AudioPlayer {
   Stream<AudioPlaybackState> get playbackStateStream =>
       _playbackStateSubject.stream;
 
+  /// Whether the player is buffering.
+  bool get buffering => _audioPlaybackEvent.buffering;
+
+  /// A stream of buffering state changes.
+  Stream<bool> get bufferingStream => _bufferingSubject.stream;
+
+  /// A stream of [FullAudioPlaybackState]s.
+  Stream<FullAudioPlaybackState> get fullPlaybackStateStream =>
+      _fullPlaybackStateSubject.stream;
+
   /// A stream periodically tracking the current position of this player.
   Stream<Duration> getPositionStream(
           [final Duration period = const Duration(milliseconds: 200)]) =>
@@ -209,10 +229,7 @@ class AudioPlayer {
   }
 
   /// Pauses the currently playing media. It is legal to invoke this method
-  /// only from the following states:
+  /// only from the [AudioPlaybackState.playing] state.
-  ///
-  /// * [AudioPlaybackState.playing]
-  /// * [AudioPlaybackState.buffering]
   Future<void> pause() async {
     await _invokeMethod('pause');
   }
@@ -272,6 +289,9 @@ class AudioPlaybackEvent {
   /// The current playback state.
   final AudioPlaybackState state;
 
+  /// Whether the player is buffering.
+  final bool buffering;
+
   /// When the last time a position discontinuity happened, as measured in time
   /// since the epoch.
   final Duration updateTime;
@@ -284,6 +304,7 @@ class AudioPlaybackEvent {
 
   AudioPlaybackEvent({
     @required this.state,
+    @required this.buffering,
     @required this.updateTime,
     @required this.updatePosition,
     @required this.speed,
@@ -308,7 +329,13 @@ enum AudioPlaybackState {
   stopped,
   paused,
   playing,
-  buffering,
   connecting,
   completed,
 }
+
+class FullAudioPlaybackState {
+  final AudioPlaybackState state;
+  final bool buffering;
+
+  FullAudioPlaybackState(this.state, this.buffering);
+}