Visualizer implementation for Android.

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

@@ -1,8 +1,14 @@
 package com.ryanheise.just_audio;
 
+import android.Manifest;
+import android.app.Activity;
 import android.content.Context;
+import android.content.pm.PackageManager;
+import android.media.audiofx.Visualizer;
 import android.net.Uri;
 import android.os.Handler;
+import androidx.core.app.ActivityCompat;
+import androidx.core.content.ContextCompat;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.ExoPlaybackException;
 import com.google.android.exoplayer2.MediaItem;
@@ -35,13 +41,13 @@ import com.google.android.exoplayer2.upstream.DefaultHttpDataSourceFactory;
 import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.Util;
 import io.flutter.Log;
+import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
 import io.flutter.plugin.common.BinaryMessenger;
-import io.flutter.plugin.common.EventChannel;
-import io.flutter.plugin.common.EventChannel.EventSink;
 import io.flutter.plugin.common.MethodCall;
 import io.flutter.plugin.common.MethodChannel;
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
 import io.flutter.plugin.common.MethodChannel.Result;
+import io.flutter.plugin.common.PluginRegistry;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -50,7 +56,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Random;
 
-public class AudioPlayer implements MethodCallHandler, Player.EventListener, AudioListener, MetadataOutput {
+public class AudioPlayer implements MethodCallHandler, Player.EventListener, AudioListener, MetadataOutput, PluginRegistry.RequestPermissionsResultListener {
 
     static final String TAG = "AudioPlayer";
 
@@ -58,8 +64,8 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener, Aud
 
     private final Context context;
     private final MethodChannel methodChannel;
-    private final EventChannel eventChannel;
+    private final BetterEventChannel eventChannel;
-    private EventSink eventSink;
+    private ActivityPluginBinding activityPluginBinding;
 
     private ProcessingState processingState;
     private long bufferedPosition;
@@ -77,6 +83,12 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener, Aud
     private IcyHeaders icyHeaders;
     private int errorCount;
     private AudioAttributes pendingAudioAttributes;
+    private BetterVisualizer visualizer;
+    private Result startVisualizerResult;
+    private boolean enableWaveform;
+    private boolean enableFft;
+    private Integer visualizerCaptureRate;
+    private Integer visualizerCaptureSize;
 
     private SimpleExoPlayer player;
     private Integer audioSessionId;
@@ -114,26 +126,50 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener, Aud
         this.context = applicationContext;
         methodChannel = new MethodChannel(messenger, "com.ryanheise.just_audio.methods." + id);
         methodChannel.setMethodCallHandler(this);
-        eventChannel = new EventChannel(messenger, "com.ryanheise.just_audio.events." + id);
+        eventChannel = new BetterEventChannel(messenger, "com.ryanheise.just_audio.events." + id);
-        eventChannel.setStreamHandler(new EventChannel.StreamHandler() {
+        visualizer = new BetterVisualizer(messenger, id);
-            @Override
-            public void onListen(final Object arguments, final EventSink eventSink) {
-                AudioPlayer.this.eventSink = eventSink;
-            }
-
-            @Override
-            public void onCancel(final Object arguments) {
-                eventSink = null;
-            }
-        });
         processingState = ProcessingState.none;
     }
 
+    private void requestPermissions() {
+        ActivityCompat.requestPermissions(activityPluginBinding.getActivity(), new String[] { Manifest.permission.RECORD_AUDIO }, 1);
+    }
+
+    public void setActivityPluginBinding(ActivityPluginBinding activityPluginBinding) {
+        if (this.activityPluginBinding != null && this.activityPluginBinding != activityPluginBinding) {
+            this.activityPluginBinding.removeRequestPermissionsResultListener(this);
+        }
+        this.activityPluginBinding = activityPluginBinding;
+        if (activityPluginBinding != null) {
+            activityPluginBinding.addRequestPermissionsResultListener(this);
+            // If there is a pending startVisualizer request
+            if (startVisualizerResult != null) {
+                requestPermissions();
+            }
+        }
+    }
+
     private void startWatchingBuffer() {
         handler.removeCallbacks(bufferWatcher);
         handler.post(bufferWatcher);
     }
 
+    @Override
+    public boolean onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
+        for (int i = 0; i < permissions.length; i++) {
+            if (permissions[i].equals(Manifest.permission.RECORD_AUDIO)) {
+                if (grantResults[i] == PackageManager.PERMISSION_GRANTED) {
+                    visualizer.setHasPermission(true);
+                    completeStartVisualizer(true);
+                    return true;
+                }
+                completeStartVisualizer(false);
+                break;
+            }
+        }
+        return false;
+    }
+
     @Override
     public void onAudioSessionId(int audioSessionId) {
         if (audioSessionId == C.AUDIO_SESSION_ID_UNSET) {
@@ -141,6 +177,7 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener, Aud
         } else {
             this.audioSessionId = audioSessionId;
         }
+        visualizer.onAudioSessionId(this.audioSessionId);
     }
 
     @Override
@@ -277,12 +314,48 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener, Aud
         seekResult = null;
     }
 
+    private void completeStartVisualizer(boolean success) {
+        if (startVisualizerResult == null) return;
+        if (success) {
+            visualizer.start(visualizerCaptureRate, visualizerCaptureSize, enableWaveform, enableFft);
+            Map<String, Object> resultMap = new HashMap<String, Object>();
+            resultMap.put("samplingRate", visualizer.getSamplingRate());
+            startVisualizerResult.success(resultMap);
+        } else {
+            startVisualizerResult.error("RECORD_AUDIO permission denied", null, null);
+        }
+        startVisualizerResult = null;
+    }
+
     @Override
     public void onMethodCall(final MethodCall call, final Result result) {
         ensurePlayerInitialized();
 
         try {
             switch (call.method) {
+            case "startVisualizer":
+                Boolean enableWaveform = call.argument("enableWaveform");
+                Boolean enableFft = call.argument("enableFft");
+                Integer captureRate = call.argument("captureRate");
+                Integer captureSize = call.argument("captureSize");
+                this.enableWaveform = enableWaveform;
+                this.enableFft = enableFft;
+                visualizerCaptureRate = captureRate;
+                visualizerCaptureSize = captureSize;
+                startVisualizerResult = result;
+                if (ContextCompat.checkSelfPermission(context, Manifest.permission.RECORD_AUDIO) == PackageManager.PERMISSION_GRANTED) {
+                    visualizer.setHasPermission(true);
+                    completeStartVisualizer(true);
+                } else if (activityPluginBinding != null && activityPluginBinding.getActivity() != null) {
+                    requestPermissions();
+                } else {
+                    // Will request permission in setActivityPluginBinding
+                }
+                break;
+            case "stopVisualizer":
+                visualizer.stop();
+                result.success(new HashMap<String, Object>());
+                break;
             case "load":
                 Long initialPosition = getLong(call.argument("initialPosition"));
                 Integer initialIndex = call.argument("initialIndex");
@@ -565,9 +638,7 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener, Aud
         event.put("currentIndex", currentIndex);
         event.put("androidAudioSessionId", audioSessionId);
 
-        if (eventSink != null) {
+        eventChannel.success(event);
-            eventSink.success(event);
-        }
     }
 
     private Map<String, Object> collectIcyMetadata() {
@@ -615,9 +686,7 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener, Aud
             prepareResult = null;
         }
 
-        if (eventSink != null) {
+        eventChannel.error(errorCode, errorMsg, null);
-            eventSink.error(errorCode, errorMsg, null);
-        }
     }
 
     private void transition(final ProcessingState newState) {
@@ -706,9 +775,8 @@ public class AudioPlayer implements MethodCallHandler, Player.EventListener, Aud
             player = null;
             transition(ProcessingState.none);
         }
-        if (eventSink != null) {
+        eventChannel.endOfStream();
-            eventSink.endOfStream();
+        visualizer.dispose();
-        }
     }
 
     private void abortSeek() {

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

@@ -0,0 +1,39 @@
+package com.ryanheise.just_audio;
+
+import io.flutter.plugin.common.BinaryMessenger;
+import io.flutter.plugin.common.EventChannel;
+import io.flutter.plugin.common.EventChannel.EventSink;
+
+public class BetterEventChannel implements EventSink {
+    private EventSink eventSink;
+
+	public BetterEventChannel(final BinaryMessenger messenger, final String id) {
+        EventChannel eventChannel = new EventChannel(messenger, id);
+        eventChannel.setStreamHandler(new EventChannel.StreamHandler() {
+            @Override
+            public void onListen(final Object arguments, final EventSink eventSink) {
+                BetterEventChannel.this.eventSink = eventSink;
+            }
+
+            @Override
+            public void onCancel(final Object arguments) {
+                eventSink = null;
+            }
+        });
+	}
+
+    @Override
+    public void success(Object event) {
+        if (eventSink != null) eventSink.success(event);
+    }
+
+    @Override
+    public void error(String errorCode, String errorMessage, Object errorDetails) {
+        if (eventSink != null) eventSink.error(errorCode, errorMessage, errorDetails);
+    }
+
+    @Override
+    public void endOfStream() {
+        if (eventSink != null) eventSink.endOfStream();
+    }
+}

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

@@ -0,0 +1,86 @@
+package com.ryanheise.just_audio;
+
+import android.media.audiofx.Visualizer;
+import io.flutter.plugin.common.BinaryMessenger;
+
+public class BetterVisualizer {
+    private Visualizer visualizer;
+    private final BetterEventChannel waveformEventChannel;
+    private final BetterEventChannel fftEventChannel;
+    private Integer audioSessionId;
+    private int captureRate;
+    private int captureSize;
+    private boolean enableWaveform;
+    private boolean enableFft;
+    private boolean pendingStartRequest;
+    private boolean hasPermission;
+
+    public BetterVisualizer(final BinaryMessenger messenger, String id) {
+        waveformEventChannel = new BetterEventChannel(messenger, "com.ryanheise.just_audio.waveform_events." + id);
+        fftEventChannel = new BetterEventChannel(messenger, "com.ryanheise.just_audio.fft_events." + id);
+    }
+
+    public int getSamplingRate() {
+        return visualizer.getSamplingRate();
+    }
+
+    public void setHasPermission(boolean hasPermission) {
+        this.hasPermission = hasPermission;
+    }
+
+    public void onAudioSessionId(Integer audioSessionId) {
+        this.audioSessionId = audioSessionId;
+        if (audioSessionId != null && hasPermission && pendingStartRequest) {
+            start(captureRate, captureSize, enableWaveform, enableFft);
+        }
+    }
+
+    public void start(Integer captureRate, Integer captureSize, final boolean enableWavefrom, final boolean enableFft) {
+        if (visualizer != null) return;
+        if (captureRate == null) {
+            captureRate = Visualizer.getMaxCaptureRate() / 2;
+        } else if (captureRate > Visualizer.getMaxCaptureRate()) {
+            captureRate = Visualizer.getMaxCaptureRate();
+        }
+        if (captureSize == null) {
+            captureSize = Visualizer.getCaptureSizeRange()[1];
+        } else if (captureSize > Visualizer.getCaptureSizeRange()[1]) {
+            captureSize = Visualizer.getCaptureSizeRange()[1];
+        } else if (captureSize < Visualizer.getCaptureSizeRange()[0]) {
+            captureSize = Visualizer.getCaptureSizeRange()[0];
+        }
+        this.enableWaveform = enableWaveform;
+        this.enableFft = enableFft;
+        this.captureRate = captureRate;
+        if (audioSessionId == null || !hasPermission) {
+            pendingStartRequest = true;
+            return;
+        }
+        pendingStartRequest = false;
+        visualizer = new Visualizer(audioSessionId);
+        visualizer.setCaptureSize(captureSize);
+        visualizer.setDataCaptureListener(new Visualizer.OnDataCaptureListener() {
+            public void onWaveFormDataCapture(Visualizer visualizer, byte[] waveform, int samplingRate) {
+                waveformEventChannel.success(waveform);
+            }
+            public void onFftDataCapture(Visualizer visualizer, byte[] fft, int samplingRate) {
+                fftEventChannel.success(fft);
+            }
+        }, captureRate, enableWavefrom, enableFft);
+        visualizer.setEnabled(true);
+    }
+
+    public void stop() {
+        if (visualizer == null) return;
+        visualizer.setDataCaptureListener(null, captureRate, enableWaveform, enableFft);
+        visualizer.setEnabled(false);
+        visualizer.release();
+        visualizer = null;
+    }
+
+    public void dispose() {
+        stop();
+        waveformEventChannel.endOfStream();
+        fftEventChannel.endOfStream();
+    }
+}

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

@@ -3,6 +3,8 @@ package com.ryanheise.just_audio;
 import android.content.Context;
 import androidx.annotation.NonNull;
 import io.flutter.embedding.engine.plugins.FlutterPlugin;
+import io.flutter.embedding.engine.plugins.activity.ActivityAware;
+import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
 import io.flutter.plugin.common.BinaryMessenger;
 import io.flutter.plugin.common.MethodChannel;
 import io.flutter.plugin.common.PluginRegistry.Registrar;
@@ -10,7 +12,7 @@ import io.flutter.plugin.common.PluginRegistry.Registrar;
 /**
  * JustAudioPlugin
  */
-public class JustAudioPlugin implements FlutterPlugin {
+public class JustAudioPlugin implements FlutterPlugin, ActivityAware {
 
     private MethodChannel channel;
     private MainMethodCallHandler methodCallHandler;
@@ -41,6 +43,25 @@ public class JustAudioPlugin implements FlutterPlugin {
         stopListening();
     }
 
+    @Override
+    public void onAttachedToActivity(ActivityPluginBinding binding) {
+        methodCallHandler.setActivityPluginBinding(binding);
+    }
+
+    @Override
+    public void onDetachedFromActivityForConfigChanges() {
+    }
+
+    @Override
+    public void onReattachedToActivityForConfigChanges(ActivityPluginBinding binding) {
+        methodCallHandler.setActivityPluginBinding(binding);
+    }
+
+    @Override
+    public void onDetachedFromActivity() {
+        methodCallHandler.setActivityPluginBinding(null);
+    }
+
     private void startListening(Context applicationContext, BinaryMessenger messenger) {
         methodCallHandler = new MainMethodCallHandler(applicationContext, messenger);
 

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

@@ -1,7 +1,9 @@
 package com.ryanheise.just_audio;
 
+import android.app.Activity;
 import android.content.Context;
 import androidx.annotation.NonNull;
+import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
 import io.flutter.plugin.common.BinaryMessenger;
 import io.flutter.plugin.common.MethodCall;
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
@@ -15,6 +17,7 @@ public class MainMethodCallHandler implements MethodCallHandler {
 
     private final Context applicationContext;
     private final BinaryMessenger messenger;
+    private ActivityPluginBinding activityPluginBinding;
 
     private final Map<String, AudioPlayer> players = new HashMap<>();
 
@@ -24,6 +27,13 @@ public class MainMethodCallHandler implements MethodCallHandler {
         this.messenger = messenger;
     }
 
+    void setActivityPluginBinding(ActivityPluginBinding activityPluginBinding) {
+        this.activityPluginBinding = activityPluginBinding;
+        for (AudioPlayer player : players.values()) {
+            player.setActivityPluginBinding(activityPluginBinding);
+        }
+    }
+
     @Override
     public void onMethodCall(MethodCall call, @NonNull Result result) {
         final Map<?, ?> request = call.arguments();
@@ -34,7 +44,11 @@ public class MainMethodCallHandler implements MethodCallHandler {
                 result.error("Platform player " + id + " already exists", null, null);
                 break;
             }
-            players.put(id, new AudioPlayer(applicationContext, messenger, id));
+            final AudioPlayer player = new AudioPlayer(applicationContext, messenger, id);
+            players.put(id, player);
+            if (activityPluginBinding != null) {
+                player.setActivityPluginBinding(activityPluginBinding);
+            }
             result.success(null);
             break;
         }

just_audio/example/android/app/src/main/AndroidManifest.xml

@@ -1,6 +1,8 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.ryanheise.just_audio_example">
 
+    <uses-permission android:name="android.permission.RECORD_AUDIO"/>
+
     <!-- io.flutter.app.FlutterApplication is an android.app.Application that
          calls FlutterMain.startInitialization(this); in its onCreate method.
          In most cases you can leave this as-is, but you if you want to provide

just_audio/example/pubspec.lock

@@ -124,16 +124,16 @@ packages:
   just_audio_platform_interface:
     dependency: transitive
     description:
-      name: just_audio_platform_interface
+      path: "../../just_audio_platform_interface"
-      url: "https://pub.dartlang.org"
+      relative: true
-    source: hosted
+    source: path
     version: "2.0.0"
   just_audio_web:
     dependency: transitive
     description:
-      name: just_audio_web
+      path: "../../just_audio_web"
-      url: "https://pub.dartlang.org"
+      relative: true
-    source: hosted
+    source: path
     version: "0.2.1"
   matcher:
     dependency: transitive

just_audio/lib/just_audio.dart

@@ -2,6 +2,7 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 import 'dart:math';
+import 'dart:typed_data';
 
 import 'package:audio_session/audio_session.dart';
 import 'package:crypto/crypto.dart';
@@ -59,15 +60,24 @@ class AudioPlayer {
   /// subscribe to the new platform's events.
   StreamSubscription _playbackEventSubscription;
 
+  /// The subscription to the event channel for waveform data.
+  StreamSubscription _visualizerWaveformSubscription;
+
+  /// The subscription to the event channel for FFT data.
+  StreamSubscription _visualizerFftSubscription;
+
   final String _id;
   _ProxyHttpServer _proxy;
   AudioSource _audioSource;
   Map<String, AudioSource> _audioSources = {};
   bool _disposed = false;
   _InitialSeekValues _initialSeekValues;
+  StartVisualizerRequest _startVisualizerRequest;
 
   PlaybackEvent _playbackEvent;
   final _playbackEventSubject = BehaviorSubject<PlaybackEvent>(sync: true);
+  final _visualizerWaveformSubject = BehaviorSubject<Uint8List>();
+  final _visualizerFftSubject = BehaviorSubject<Uint8List>();
   Future<Duration> _durationFuture;
   final _durationSubject = BehaviorSubject<Duration>();
   final _processingStateSubject = BehaviorSubject<ProcessingState>();
@@ -227,6 +237,13 @@ class AudioPlayer {
   /// A stream of [PlaybackEvent]s.
   Stream<PlaybackEvent> get playbackEventStream => _playbackEventSubject.stream;
 
+  /// A stream of visualizer waveform data in unsigned 8 bit PCM..
+  Stream<Uint8List> get visualizerWaveformStream =>
+      _visualizerWaveformSubject.stream;
+
+  /// A stream of visualizer FFT data.
+  Stream<Uint8List> get visualizerFftStream => _visualizerFftSubject.stream;
+
   /// The duration of the current audio or null if unknown.
   Duration get duration => _playbackEvent.duration;
 
@@ -894,11 +911,42 @@ class AudioPlayer {
         usage: audioAttributes.usage.value));
   }
 
+  /// Start the visualizer by capturing [captureSize] samples of audio at
+  /// [captureRate] millihertz and return the sampling rate of the audio. If
+  /// [enableWaveform] is `true`, the captured samples will be broadcast via
+  /// [visualizerWaveformStream]. If [enableFft] is `true`, the FFT data for
+  /// each capture will be broadcast via [visualizerFftStream]. You should call
+  /// [stopVisualizer] to stop capturing audio data.
+  Future<int> startVisualizer({
+    bool enableWaveform = true,
+    bool enableFft = true,
+    int captureRate,
+    int captureSize,
+  }) async {
+    return (await (await _platform).startVisualizer(_startVisualizerRequest =
+            StartVisualizerRequest(
+                enableWaveform: enableWaveform,
+                enableFft: enableFft,
+                captureRate: captureRate,
+                captureSize: captureSize)))
+        ?.samplingRate;
+  }
+
+  /// Stop capturing audio data for the visualizer.
+  Future<void> stopVisualizer() async {
+    _startVisualizerRequest = null;
+    (await _platform).stopVisualizer(StopVisualizerRequest());
+  }
+
   /// Release all resources associated with this player. You must invoke this
   /// after you are done with the player.
   Future<void> dispose() async {
     if (_disposed) return;
     _disposed = true;
+    await _visualizerWaveformSubscription?.cancel();
+    await _visualizerFftSubscription?.cancel();
+    await _visualizerWaveformSubject.close();
+    await _visualizerFftSubject.close();
     if (_nativePlatform != null) {
       await _disposePlatform(await _nativePlatform);
       _nativePlatform = null;
@@ -940,6 +988,8 @@ class AudioPlayer {
     final durationCompleter = Completer<Duration>();
     _platform = Future<AudioPlayerPlatform>(() async {
       _playbackEventSubscription?.cancel();
+      _visualizerWaveformSubscription?.cancel();
+      _visualizerFftSubscription?.cancel();
       if (oldPlatformFuture != null) {
         final oldPlatform = await oldPlatformFuture;
         if (oldPlatform != _idlePlatform) {
@@ -953,6 +1003,10 @@ class AudioPlayer {
           ? await (_nativePlatform =
               JustAudioPlatform.instance.init(InitRequest(id: _id)))
           : _idlePlatform;
+      _visualizerWaveformSubscription = platform.visualizerWaveformStream
+          .listen(_visualizerWaveformSubject.add);
+      _visualizerFftSubscription =
+          platform.visualizerFftStream.listen(_visualizerFftSubject.add);
       _playbackEventSubscription =
           platform.playbackEventMessageStream.listen((message) {
         var duration = message.duration;
@@ -1005,6 +1059,9 @@ class AudioPlayer {
               SetAutomaticallyWaitsToMinimizeStallingRequest(
                   enabled: automaticallyWaitsToMinimizeStalling));
         }
+        if (_startVisualizerRequest != null) {
+          await platform.startVisualizer(_startVisualizerRequest);
+        }
         await platform.setVolume(SetVolumeRequest(volume: volume));
         await platform.setSpeed(SetSpeedRequest(speed: speed));
         await platform.setLoopMode(SetLoopModeRequest(
@@ -2273,6 +2330,8 @@ enum LoopMode { off, one, all }
 /// state and the native platform is deallocated.
 class _IdleAudioPlayer extends AudioPlayerPlatform {
   final _eventSubject = BehaviorSubject<PlaybackEventMessage>();
+  final _visualizerWaveformSubject = BehaviorSubject<Uint8List>();
+  final _visualizerFftSubject = BehaviorSubject<Uint8List>();
   Duration _position;
   int _index;
   List<IndexedAudioSource> _sequence;
@@ -2310,6 +2369,13 @@ class _IdleAudioPlayer extends AudioPlayerPlatform {
   Stream<PlaybackEventMessage> get playbackEventMessageStream =>
       _eventSubject.stream;
 
+  @override
+  Stream<Uint8List> get visualizerWaveformStream =>
+      _visualizerWaveformSubject.stream;
+
+  @override
+  Stream<Uint8List> get visualizerFftStream => _visualizerFftSubject.stream;
+
   @override
   Future<LoadResponse> load(LoadRequest request) async {
     _index = request.initialIndex ?? 0;
@@ -2379,6 +2445,9 @@ class _IdleAudioPlayer extends AudioPlayerPlatform {
 
   @override
   Future<DisposeResponse> dispose(DisposeRequest request) async {
+    await _eventSubject.close();
+    await _visualizerWaveformSubject.close();
+    await _visualizerFftSubject.close();
     return DisposeResponse();
   }
 
@@ -2399,6 +2468,18 @@ class _IdleAudioPlayer extends AudioPlayerPlatform {
       ConcatenatingMoveRequest request) async {
     return ConcatenatingMoveResponse();
   }
+
+  @override
+  Future<StartVisualizerResponse> startVisualizer(
+      StartVisualizerRequest request) async {
+    return StartVisualizerResponse();
+  }
+
+  @override
+  Future<StopVisualizerResponse> stopVisualizer(
+      StopVisualizerRequest request) async {
+    return StopVisualizerResponse();
+  }
 }
 
 /// Holds the initial requested position and index for a newly loaded audio

just_audio/pubspec.lock

@@ -194,16 +194,16 @@ packages:
   just_audio_platform_interface:
     dependency: "direct main"
     description:
-      name: just_audio_platform_interface
+      path: "../just_audio_platform_interface"
-      url: "https://pub.dartlang.org"
+      relative: true
-    source: hosted
+    source: path
     version: "2.0.0"
   just_audio_web:
     dependency: "direct main"
     description:
-      name: just_audio_web
+      path: "../just_audio_web"
-      url: "https://pub.dartlang.org"
+      relative: true
-    source: hosted
+    source: path
     version: "0.2.1"
   logging:
     dependency: transitive

just_audio/pubspec.yaml

@@ -8,8 +8,12 @@ environment:
   flutter: ">=1.12.13+hotfix.5"
 
 dependencies:
-  just_audio_platform_interface: ^2.0.0
+  # just_audio_platform_interface: ^2.0.0
-  just_audio_web: ^0.2.1
+  just_audio_platform_interface:
+    path: ../just_audio_platform_interface
+  # just_audio_web: ^0.2.1
+  just_audio_web:
+    path: ../just_audio_web
   audio_session: ^0.0.10
   rxdart: ">= 0.24.1 < 0.26.0"
   path: ^1.6.4

just_audio_platform_interface/lib/just_audio_platform_interface.dart

@@ -1,4 +1,5 @@
 import 'dart:async';
+import 'dart:typed_data';
 
 import 'package:flutter/foundation.dart';
 import 'package:meta/meta.dart' show required;
@@ -68,6 +69,17 @@ abstract class AudioPlayerPlatform {
         'playbackEventMessageStream has not been implemented.');
   }
 
+  /// A stream of visualizer waveform data.
+  Stream<Uint8List> get visualizerWaveformStream {
+    throw UnimplementedError(
+        'visualizerWaveformStream has not been implemented.');
+  }
+
+  /// A stream of visualizer fft data.
+  Stream<Uint8List> get visualizerFftStream {
+    throw UnimplementedError('visualizerFftStream has not been implemented.');
+  }
+
   /// Loads an audio source.
   Future<LoadResponse> load(LoadRequest request) {
     throw UnimplementedError("load() has not been implemented.");
@@ -157,6 +169,17 @@ abstract class AudioPlayerPlatform {
       ConcatenatingMoveRequest request) {
     throw UnimplementedError("concatenatingMove() has not been implemented.");
   }
+
+  /// Starts the visualizer.
+  Future<StartVisualizerResponse> startVisualizer(
+      StartVisualizerRequest request) {
+    throw UnimplementedError("startVisualizer() has not been implemented.");
+  }
+
+  /// Stops the visualizer.
+  Future<StopVisualizerResponse> stopVisualizer(StopVisualizerRequest request) {
+    throw UnimplementedError("stopVisualizer() has not been implemented.");
+  }
 }
 
 /// A playback event communicated from the platform implementation to the
@@ -624,6 +647,53 @@ class ConcatenatingMoveResponse {
       ConcatenatingMoveResponse();
 }
 
+/// Information communicated to the platform implementation when starting the
+/// visualizer.
+class StartVisualizerRequest {
+  final bool enableWaveform;
+  final bool enableFft;
+  final int captureRate;
+  final int captureSize;
+
+  StartVisualizerRequest({
+    @required this.enableWaveform,
+    @required this.enableFft,
+    @required this.captureRate,
+    @required this.captureSize,
+  });
+
+  Map<dynamic, dynamic> toMap() => {
+        'enableWaveform': enableWaveform,
+        'enableFft': enableFft,
+        'captureRate': captureRate,
+        'captureSize': captureSize,
+      };
+}
+
+/// Information returned by the platform implementation after starting the
+/// visualizer.
+class StartVisualizerResponse {
+  final int samplingRate;
+
+  StartVisualizerResponse({@required this.samplingRate});
+
+  static StartVisualizerResponse fromMap(Map<dynamic, dynamic> map) =>
+      StartVisualizerResponse(samplingRate: map['samplingRate']);
+}
+
+/// Information communicated to the platform implementation when stopping the
+/// visualizer.
+class StopVisualizerRequest {
+  Map<dynamic, dynamic> toMap() => {};
+}
+
+/// Information returned by the platform implementation after stopping the
+/// visualizer.
+class StopVisualizerResponse {
+  static StopVisualizerResponse fromMap(Map<dynamic, dynamic> map) =>
+      StopVisualizerResponse();
+}
+
 /// Information about an audio source to be communicated with the platform
 /// implementation.
 abstract class AudioSourceMessage {

just_audio_platform_interface/lib/method_channel_just_audio.dart

@@ -1,4 +1,5 @@
 import 'dart:async';
+import 'dart:typed_data';
 
 import 'package:flutter/services.dart';
 
@@ -36,6 +37,18 @@ class MethodChannelAudioPlayer extends AudioPlayerPlatform {
           .receiveBroadcastStream()
           .map((map) => PlaybackEventMessage.fromMap(map));
 
+  @override
+  Stream<Uint8List> get visualizerWaveformStream =>
+      EventChannel('com.ryanheise.just_audio.waveform_events.$id')
+          .receiveBroadcastStream()
+          .cast<Uint8List>();
+
+  @override
+  Stream<Uint8List> get visualizerFftStream =>
+      EventChannel('com.ryanheise.just_audio.fft_events.$id')
+          .receiveBroadcastStream()
+          .cast<Uint8List>();
+
   @override
   Future<LoadResponse> load(LoadRequest request) async {
     return LoadResponse.fromMap(
@@ -134,4 +147,18 @@ class MethodChannelAudioPlayer extends AudioPlayerPlatform {
     return ConcatenatingMoveResponse.fromMap(
         await _channel.invokeMethod('concatenatingMove', request?.toMap()));
   }
+
+  @override
+  Future<StartVisualizerResponse> startVisualizer(
+      StartVisualizerRequest request) async {
+    return StartVisualizerResponse.fromMap(
+        await _channel.invokeMethod('startVisualizer', request?.toMap()));
+  }
+
+  @override
+  Future<StopVisualizerResponse> stopVisualizer(
+      StopVisualizerRequest request) async {
+    return StopVisualizerResponse.fromMap(
+        await _channel.invokeMethod('stopVisualizer', request?.toMap()));
+  }
 }

just_audio_web/pubspec.yaml

@@ -11,7 +11,9 @@ flutter:
         fileName: just_audio_web.dart
 
 dependencies:
-  just_audio_platform_interface: ^2.0.0
+  # just_audio_platform_interface: ^2.0.0
+  just_audio_platform_interface:
+    path: ../just_audio_platform_interface
   flutter:
     sdk: flutter
   flutter_web_plugins: