Simulcast, Screen sharing & Various improvements (#4)

* Respect `RTCIceTransportPolicy` enum and organize * Simplify syntax where possible etc. * Combine `VideoPreset` and `VideoPresets` * Default values for `ConnectOptions` * Build URI instead of String manipulation * Slight modifications to Exception * `LiveKitTheme` for example * `VideoEncoding` class * Organize imports * First simulcast implementation * Remove unnecessary try-catches * Update Android settings * Remember uri and token * example improvements * `fit` parameter for VideoTrackRenderer * Simulcast option for example * Pass `defaultPublishOptions` * Show only `VideoQuality` * Pass tests * Better buildUri logic * Named parameter to positional * Explicit imports * `VideoParameter` instead of `VideoPreset` * Use `mediaTrack.getSettings` when possible * Safer dispose logic * Safer `PCTransport` Update transport.dart * Synchronized events for `SignalClient` * Use logger instead of print * Make example compile for iOS * First screen share implementation * Make example work with screen share * Example improvement * Code optimization * Don't depend on web_socket_channel * Fix: Unpublish track bug * Show participant mute state & identity * Update protos * Remote mute/unmute * iOS Background mode * Separate `createCameraTrack` and `createScreenTrack` * Clean up * PB fix * format * Fix analyzer warning * Android clean up * Update README.md * Clean up
2021-09-11 03:14:14 +09:00
parent 8e66e324f6
commit 50f56c5e1e
69 changed files with 2653 additions and 2351 deletions
@@ -1,29 +1,29 @@
 import 'package:flutter_webrtc/flutter_webrtc.dart';

-import '../proto/livekit_models.pbenum.dart';
+import '../proto/livekit_models.pb.dart' as lk_models;
+import '_audio_api.dart' if (dart.library.html) '_audio_html.dart' as audio;
 import 'local_audio_track.dart';
 import 'track.dart';
-import '_audio_api.dart' if (dart.library.html) '_audio_html.dart' as audio;

 class AudioTrack extends Track {
  MediaStream? mediaStream;

  AudioTrack(String name, MediaStreamTrack track, this.mediaStream)
-      : super(TrackType.AUDIO, name, track);
+      : super(lk_models.TrackType.AUDIO, name, track);

  /// Start playing audio track. On web platform, create an audio element and
  /// start playback
  void start() {
    if (this is! LocalAudioTrack) {
-      audio.startAudio(getCid(), mediaTrack);
+      audio.startAudio(getCid(), mediaStreamTrack);
    }
  }

  @override
-  void stop() {
-    mediaStream?.dispose();
+  Future<void> stop() async {
+    await mediaStream?.dispose();
    mediaStream = null;
    audio.stopAudio(getCid());
-    super.stop();
+    await super.stop();
  }
 }
@@ -1,28 +1,28 @@
+import 'dart:async';
+
 import 'package:flutter_webrtc/flutter_webrtc.dart';
-import 'package:livekit_client/src/track/audio_track.dart';

 import '../errors.dart';
+import 'audio_track.dart';
 import 'options.dart';

 class LocalAudioTrack extends AudioTrack {
-  LocalAudioTrack(String name, MediaStreamTrack track, MediaStream stream)
-      : super(name, track, stream);
+  LocalAudioTrack(
+    String name,
+    MediaStreamTrack track,
+    MediaStream stream,
+  ) : super(name, track, stream);

  /// Creates a new audio track from the default audio input device.
-  static Future<LocalAudioTrack> createTrack([LocalAudioTrackOptions? options]) async {
-    try {
-      final stream = await navigator.mediaDevices.getUserMedia(<String, dynamic>{
-        'audio': true,
-        'video': false,
-      });
+  static Future<LocalAudioTrack> create([LocalAudioTrackOptions? options]) async {
+    // try {
+    final stream = await navigator.mediaDevices.getUserMedia(<String, dynamic>{
+      'audio': true,
+      'video': false,
+    });

-      if (stream.getAudioTracks().isEmpty) {
-        return Future.error(TrackCreateError());
-      }
+    if (stream.getAudioTracks().isEmpty) throw TrackCreateError();

-      return LocalAudioTrack('', stream.getAudioTracks().first, stream);
-    } catch (e) {
-      return Future.error(e);
-    }
+    return LocalAudioTrack('', stream.getAudioTracks().first, stream);
  }
 }
@@ -1,23 +1,29 @@
+import 'package:livekit_client/src/logger.dart';
+
 import '../participant/local_participant.dart';
-import '../proto/livekit_models.pb.dart';
+import '../proto/livekit_models.pb.dart' as lk_models;
 import 'track.dart';
 import 'track_publication.dart';

 class LocalTrackPublication extends TrackPublication {
  final LocalParticipant _participant;

-  LocalTrackPublication(TrackInfo info, Track track, this._participant) : super.fromInfo(info) {
+  LocalTrackPublication(
+    lk_models.TrackInfo info,
+    Track track,
+    this._participant,
+  ) : super.fromInfo(info) {
    this.track = track;
  }

  /// Mute or unmute the current track. When muted, track will stop sending data
  @override
  set muted(bool val) {
-    if (val == muted) {
-      return;
-    }
+    if (val == muted) return;
+    logger.finer('setMute: ${val}');
+
    super.muted = val;
-    track?.mediaTrack.enabled = !val;
+    track?.mediaStreamTrack.enabled = !val;
    _participant.engine.client.sendMuteTrack(sid, val);

    if (val) {
@@ -1,66 +1,113 @@
 import 'package:flutter_webrtc/flutter_webrtc.dart';

 import '../errors.dart';
+import '../logger.dart';
 import 'options.dart';
+import 'track.dart';
 import 'video_track.dart';

 /// A video track from the local device. Use static methods in this class to create
 /// video tracks.
 class LocalVideoTrack extends VideoTrack {
+  //
+  // Options used for this track
+  //
+  LocalVideoTrackOptions currentOptions;
+
+  //
+  // Private constructor
+  //
+  LocalVideoTrack._(
+    String name,
+    MediaStreamTrack mediaTrack,
+    MediaStream stream,
+    this.currentOptions,
+  ) : super(name, mediaTrack, stream);
+
  RTCRtpSender? get sender => transceiver?.sender;

-  LocalVideoTrack(String name, MediaStreamTrack mediaTrack, MediaStream stream)
-      : super(name, mediaTrack, stream);
-
-  /// Creates a LocalVideoTrack from camera input.
-  static Future<LocalVideoTrack> createCameraTrack([LocalVideoTrackOptions? options]) async {
-    options ??= LocalVideoTrackOptions(params: VideoPresets.qhd);
-
-    try {
-      final stream = await _createCameraStream(options);
-      return LocalVideoTrack('camera', stream.getVideoTracks().first, stream);
-    } catch (e) {
-      return Future.error(e);
-    }
-  }
-
  /// Restarts the track with new options. This is useful when switching between
  /// front and back cameras.
-  Future<void> restartTrack([LocalVideoTrackOptions? options]) async {
-    if (sender == null) {
-      return Future.error(TrackCreateError('could not restart track'));
+  Future<void> restartTrack([
+    LocalVideoTrackOptions? options,
+  ]) async {
+    if (sender == null) throw TrackCreateError('could not restart track');
+    if (options != null && currentOptions.runtimeType != options.runtimeType) {
+      throw Exception('options must be a ${currentOptions.runtimeType}');
    }

-    options ??= LocalVideoTrackOptions(params: VideoPresets.qhd);
+    currentOptions = options ?? currentOptions;

-    try {
-      final stream = await _createCameraStream(options);
-      final track = stream.getVideoTracks().first;
-      mediaStream = stream;
-      await mediaTrack.stop();
-      mediaTrack = track;
-      await sender?.replaceTrack(track);
-    } catch (e) {
-      return Future.error(e);
-    }
+    final stream = await _createStream(currentOptions);
+    final track = stream.getVideoTracks().first;
+    setMediaStream(stream);
+    await mediaStreamTrack.stop();
+    mediaStreamTrack = track;
+    await sender?.replaceTrack(track);
  }

-  static Future<MediaStream> _createCameraStream(LocalVideoTrackOptions? options) async {
-    options ??= LocalVideoTrackOptions(params: VideoPresets.qhd);
+  /// Creates a LocalVideoTrack from camera input.
+  static Future<LocalVideoTrack> createCameraTrack([
+    CameraTrackOptions? options,
+  ]) async {
+    options ??= const CameraTrackOptions();
+    final stream = await _createStream(options);
+    return LocalVideoTrack._(
+      Track.cameraName,
+      stream.getVideoTracks().first,
+      stream,
+      options,
+    );
+  }

-    try {
-      final stream = await navigator.mediaDevices.getUserMedia(<String, dynamic>{
-        'audio': false,
-        'video': options.mediaConstraints,
-      });
+  static Future<LocalVideoTrack> createScreenTrack([
+    ScreenTrackOptions? options,
+  ]) async {
+    options ??= const ScreenTrackOptions();
+    final stream = await _createStream(options);
+    return LocalVideoTrack._(
+      Track.screenShareName,
+      stream.getVideoTracks().first,
+      stream,
+      options,
+    );
+  }

-      if (stream.getVideoTracks().isEmpty) {
-        return Future.error(TrackCreateError());
-      }
+  static Future<MediaStream> _createStream(
+    LocalVideoTrackOptions options,
+  ) async {
+    final constraints = <String, dynamic>{
+      'audio': false,
+      'video': options.toMediaConstraintsMap(),
+    };

-      return stream;
-    } catch (e) {
-      return Future.error(e);
+    final MediaStream stream;
+    if (options is ScreenTrackOptions) {
+      stream = await navigator.mediaDevices.getDisplayMedia(constraints);
+    } else {
+      // options is CameraVideoTrackOptions
+      stream = await navigator.mediaDevices.getUserMedia(constraints);
    }
+
+    if (stream.getVideoTracks().isEmpty) throw TrackCreateError();
+    return stream;
+  }
+}
+
+//
+// Convenience extensions
+//
+extension LKLocalVideoTrackExt on LocalVideoTrack {
+  // Calls restartTrack under the hood
+  Future<void> setCameraPosition(CameraPosition position) async {
+    final options = currentOptions;
+    if (options is! CameraTrackOptions) {
+      logger.warning('Not a camera track');
+      return;
+    }
+
+    await restartTrack(
+      options.copyWith(cameraPosition: position),
+    );
  }
 }
@@ -1,26 +1,8 @@
-/// Options when creating a LocalVideoTrack.
-class LocalVideoTrackOptions {
-  CameraPosition position = CameraPosition.front;
-  VideoParameter params;
+import 'package:flutter_webrtc/flutter_webrtc.dart';

-  LocalVideoTrackOptions({
-    VideoParameter? params,
-    CameraPosition? position,
-  }) : params = VideoPresets.qhd {
-    if (params != null) {
-      this.params = params;
-    }
-    if (position != null) {
-      this.position = position;
-    }
-  }
-
-  Map<String, dynamic> get mediaConstraints {
-    return <String, dynamic>{
-      'mandatory': params.mediaConstraints,
-      'facingMode': position == CameraPosition.front ? 'user' : 'environment',
-    };
-  }
+enum LocalVideoTrackType {
+  camera,
+  display,
 }

 enum CameraPosition {
@@ -28,43 +10,229 @@ enum CameraPosition {
  back,
 }

-class VideoParameter {
-  int width;
-  int height;
-  int fps;
-  int? bitrate;
-
-  VideoParameter(
-    this.width,
-    this.height,
-    this.fps, {
-    this.bitrate,
-  });
-
-  Map<String, dynamic> get mediaConstraints {
-    return <String, dynamic>{
-      'minWidth': width,
-      'minHeight': height,
-      'minFrameRate': fps,
-    };
-  }
+extension LKCameraPositionExt on CameraPosition {
+  CameraPosition swap() => {
+        CameraPosition.front: CameraPosition.back,
+        CameraPosition.back: CameraPosition.front,
+      }[this]!;
 }

-class VideoPresets {
-  static final qvga = VideoParameter(320, 180, 15);
-  static final vga = VideoParameter(640, 360, 30);
-  static final qhd = VideoParameter(960, 540, 30);
-  static final hd = VideoParameter(1280, 720, 30);
-  static final fhd = VideoParameter(1920, 1080, 30);
+class CameraTrackOptions extends LocalVideoTrackOptions {
+  final CameraPosition cameraPosition;

-  static final List<VideoParameter> all = [
-    qvga,
-    vga,
-    qhd,
-    hd,
-    fhd,
+  const CameraTrackOptions({
+    this.cameraPosition = CameraPosition.front,
+    VideoParameters params = VideoParameters.presetQHD169,
+  }) : super(params: params);
+
+  @override
+  Map<String, dynamic> toMediaConstraintsMap() => <String, dynamic>{
+        ...super.toMediaConstraintsMap(),
+        'facingMode': cameraPosition == CameraPosition.front ? 'user' : 'environment',
+      };
+
+  // Returns new options with updated properties
+  CameraTrackOptions copyWith({
+    VideoParameters? params,
+    CameraPosition? cameraPosition,
+  }) =>
+      CameraTrackOptions(
+        params: params ?? this.params,
+        cameraPosition: cameraPosition ?? this.cameraPosition,
+      );
+}
+
+class ScreenTrackOptions extends LocalVideoTrackOptions {
+  const ScreenTrackOptions();
+}
+
+/// Options when creating a LocalVideoTrack.
+abstract class LocalVideoTrackOptions {
+  // final LocalVideoTrackType type;
+  final VideoParameters params;
+
+  const LocalVideoTrackOptions({
+    this.params = VideoParameters.presetQHD169,
+  });
+
+  Map<String, dynamic> toMediaConstraintsMap() => <String, dynamic>{
+        'mandatory': params.toMediaConstraintsMap(),
+      };
+}
+
+class VideoEncoding {
+  final int maxFramerate;
+  final int? maxBitrate;
+
+  const VideoEncoding({
+    required this.maxFramerate,
+    this.maxBitrate,
+  });
+
+  @override
+  String toString() => '${runtimeType}(maxFramerate: ${maxFramerate}, maxBitrate: ${maxBitrate})';
+}
+
+extension VideoEncodingExt on VideoEncoding {
+  RTCRtpEncoding toRTCRtpEncoding({
+    String? rid,
+    double? scaleResolutionDownBy = 1.0,
+    int? numTemporalLayers,
+  }) =>
+      RTCRtpEncoding(
+        rid: rid,
+        scaleResolutionDownBy: scaleResolutionDownBy,
+        maxFramerate: maxFramerate,
+        maxBitrate: maxBitrate,
+        numTemporalLayers: numTemporalLayers,
+      );
+}
+
+class VideoParameters {
+  final String description;
+  final int width;
+  final int height;
+  final VideoEncoding encoding;
+
+  const VideoParameters({
+    required this.description,
+    required this.width,
+    required this.height,
+    required this.encoding,
+  });
+
+  //
+  // TODO: Make sure the resolutions are correct
+  //
+
+  static const presetQVGA169 = VideoParameters(
+    description: 'QVGA(320x180) 16:9',
+    width: 320,
+    height: 180,
+    encoding: VideoEncoding(
+      maxBitrate: 125000,
+      maxFramerate: 15,
+    ),
+  );
+
+  static const presetVGA169 = VideoParameters(
+    description: 'VGA(640x360) 16:9',
+    width: 640,
+    height: 360,
+    encoding: VideoEncoding(
+      maxBitrate: 400000,
+      maxFramerate: 30,
+    ),
+  );
+
+  static const presetQHD169 = VideoParameters(
+    description: 'QHD(960x540) 16:9',
+    width: 960,
+    height: 540,
+    encoding: VideoEncoding(
+      maxBitrate: 800000,
+      maxFramerate: 30,
+    ),
+  );
+
+  static const presetHD169 = VideoParameters(
+    description: 'HD(1280x720) 16:9',
+    width: 1280,
+    height: 720,
+    encoding: VideoEncoding(
+      maxBitrate: 2500000,
+      maxFramerate: 30,
+    ),
+  );
+
+  static const presetFHD169 = VideoParameters(
+    description: 'FHD(1920x1080) 16:9',
+    width: 1920,
+    height: 1080,
+    encoding: VideoEncoding(
+      maxBitrate: 4000000,
+      maxFramerate: 30,
+    ),
+  );
+
+  static const presetQVGA43 = VideoParameters(
+    description: 'QVGA(240x180) 4:3',
+    width: 240,
+    height: 180,
+    encoding: VideoEncoding(
+      maxBitrate: 100000,
+      maxFramerate: 15,
+    ),
+  );
+
+  static const presetVGA43 = VideoParameters(
+    description: 'VGA(480x360) 4:3',
+    width: 480,
+    height: 360,
+    encoding: VideoEncoding(
+      maxBitrate: 320000,
+      maxFramerate: 30,
+    ),
+  );
+
+  static const presetQHD43 = VideoParameters(
+    description: 'QHD(720x540) 4:3',
+    width: 720,
+    height: 540,
+    encoding: VideoEncoding(
+      maxBitrate: 640000,
+      maxFramerate: 30,
+    ),
+  );
+
+  static const presetHD43 = VideoParameters(
+    description: 'HD(960x720) 4:3',
+    width: 960,
+    height: 720,
+    encoding: VideoEncoding(
+      maxBitrate: 2000000,
+      maxFramerate: 30,
+    ),
+  );
+
+  static const presetFHD43 = VideoParameters(
+    description: 'FHD(1440x1080) 4:3',
+    width: 1440,
+    height: 1080,
+    encoding: VideoEncoding(
+      maxBitrate: 3200000,
+      maxFramerate: 30,
+    ),
+  );
+
+  static final List<VideoParameters> presets169 = [
+    presetQVGA169,
+    presetVGA169,
+    presetQHD169,
+    presetHD169,
+    presetFHD169,
  ];
+
+  static final List<VideoParameters> presets43 = [
+    presetQVGA43,
+    presetVGA43,
+    presetQHD43,
+    presetHD43,
+    presetFHD43,
+  ];
+
+  //
+  // TODO: Return constraints that will work for all platforms (Web & Mobile)
+  // https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/getUserMedia
+  //
+  Map<String, dynamic> toMediaConstraintsMap() => <String, dynamic>{
+        'maxWidth': width,
+        'maxHeight': height,
+        'maxFrameRate': encoding.maxFramerate,
+      };
 }

 /// Options when creating an LocalAudioTrack. Placeholder for now.
-class LocalAudioTrackOptions {}
+class LocalAudioTrackOptions {
+  const LocalAudioTrackOptions();
+}
@@ -1,6 +1,6 @@
-import '../proto/livekit_models.pb.dart';
-import '../proto/livekit_rtc.pbserver.dart';
 import '../participant/remote_participant.dart';
+import '../proto/livekit_models.pb.dart' as lk_models;
+import '../proto/livekit_rtc.pb.dart' as lk_rtc;
 import 'track.dart';
 import 'track_publication.dart';

@@ -10,10 +10,11 @@ class RemoteTrackPublication extends TrackPublication {
  final RemoteParticipant _participant;
  bool _unsubscribed = false;
  bool _disabled = false;
-  VideoQuality _videoQuality = VideoQuality.HIGH;
+  lk_rtc.VideoQuality _videoQuality = lk_rtc.VideoQuality.HIGH;

-  VideoQuality get videoQuality => _videoQuality;
-  set videoQuality(VideoQuality val) {
+  lk_rtc.VideoQuality get videoQuality => _videoQuality;
+
+  set videoQuality(lk_rtc.VideoQuality val) {
    if (val == _videoQuality) return;
    _videoQuality = val;
    _sendUpdateTrackSettings();
@@ -56,21 +57,25 @@ class RemoteTrackPublication extends TrackPublication {
      _participant.roomDelegate?.onTrackUnmuted(_participant, this);
    }
    if (subscribed) {
-      track?.mediaTrack.enabled = !val;
+      track?.mediaStreamTrack.enabled = !val;
    }
    _participant.muteChanged();
  }

-  RemoteTrackPublication(TrackInfo info, this._participant, [Track? track]) : super.fromInfo(info) {
+  RemoteTrackPublication(
+    lk_models.TrackInfo info,
+    this._participant, [
+    Track? track,
+  ]) : super.fromInfo(info) {
    this.track = track;
  }

  void _sendUpdateTrackSettings() {
-    final settings = UpdateTrackSettings(
+    final settings = lk_rtc.UpdateTrackSettings(
      trackSids: [sid],
      disabled: _disabled,
    );
-    if (kind == TrackType.VIDEO) {
+    if (kind == lk_models.TrackType.VIDEO) {
      settings.quality = _videoQuality;
    }
    _participant.client.sendUpdateTrackSettings(settings);
@@ -1,7 +1,7 @@
 import 'package:flutter_webrtc/flutter_webrtc.dart';
 import 'package:uuid/uuid.dart';

-import '../proto/livekit_models.pb.dart';
+import '../proto/livekit_models.pb.dart' as lk_models;

 class TrackDimension {
  int width;
@@ -12,24 +12,25 @@ class TrackDimension {

 /// Wrapper around a MediaStreamTrack with additional metadata.
 class Track {
+  static const cameraName = 'camera';
  static const screenShareName = 'screen';

  String name;
-  TrackType kind;
-  MediaStreamTrack mediaTrack;
+  lk_models.TrackType kind;
+  MediaStreamTrack mediaStreamTrack;
  String? sid;
  RTCRtpTransceiver? transceiver;
  String? _cid;

-  Track(this.kind, this.name, this.mediaTrack);
+  Track(this.kind, this.name, this.mediaStreamTrack);

-  bool get muted => mediaTrack.muted == null ? false : mediaTrack.muted!;
+  bool get muted => mediaStreamTrack.muted == null ? false : mediaStreamTrack.muted!;

  RTCRtpMediaType get mediaType {
    switch (kind) {
-      case TrackType.AUDIO:
+      case lk_models.TrackType.AUDIO:
        return RTCRtpMediaType.RTCRtpMediaTypeAudio;
-      case TrackType.VIDEO:
+      case lk_models.TrackType.VIDEO:
        return RTCRtpMediaType.RTCRtpMediaTypeVideo;
      // this should never happen
      default:
@@ -38,7 +39,7 @@ class Track {
  }

  String getCid() {
-    var cid = _cid ?? mediaTrack.id;
+    var cid = _cid ?? mediaStreamTrack.id;

    if (cid == null) {
      const uuid = Uuid();
@@ -48,7 +49,7 @@ class Track {
    return cid;
  }

-  void stop() {
-    mediaTrack.stop();
+  Future<void> stop() async {
+    await mediaStreamTrack.stop();
  }
 }
@@ -1,4 +1,4 @@
-import '../proto/livekit_models.pb.dart';
+import '../proto/livekit_models.pb.dart' as lk_models;
 import 'track.dart';

 /// Represents a track that's published to the server. This class contains
@@ -7,14 +7,14 @@ class TrackPublication {
  Track? track;
  String name;
  String sid;
-  TrackType kind;
+  lk_models.TrackType kind;
  bool muted = false;
  bool simulcasted = false;
  TrackDimension? dimension;

  bool get subscribed => track != null;

-  TrackPublication.fromInfo(TrackInfo info)
+  TrackPublication.fromInfo(lk_models.TrackInfo info)
      : sid = info.sid,
        name = info.name,
        kind = info.type {
@@ -22,12 +22,12 @@ class TrackPublication {
  }

  /// True when the track is published with name [Track.screenShareName].
-  bool get isScreenShare => kind == TrackType.VIDEO && name == Track.screenShareName;
+  bool get isScreenShare => kind == lk_models.TrackType.VIDEO && name == Track.screenShareName;

-  void updateFromInfo(TrackInfo info) {
+  void updateFromInfo(lk_models.TrackInfo info) {
    muted = info.muted;
    simulcasted = info.simulcast;
-    if (info.type == TrackType.VIDEO) {
+    if (info.type == lk_models.TrackType.VIDEO) {
      dimension = TrackDimension(info.width, info.height);
    }
  }
@@ -1,29 +1,37 @@
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_webrtc/flutter_webrtc.dart';

-import '../proto/livekit_models.pb.dart';
+import '../proto/livekit_models.pb.dart' as lk_models;
 import 'track.dart';

 /// A video track will notify when its mediaTrack has changed.
 class VideoTrack extends Track with ChangeNotifier {
-  MediaStream? _mediaStream;
+  MediaStream _mediaStream;

-  VideoTrack(String name, MediaStreamTrack mediaTrack, this._mediaStream)
-      : super(TrackType.VIDEO, name, mediaTrack);
+  VideoTrack(
+    String name,
+    MediaStreamTrack mediaTrack,
+    this._mediaStream,
+  ) : super(
+          lk_models.TrackType.VIDEO,
+          name,
+          mediaTrack,
+        );

-  MediaStream? get mediaStream => _mediaStream;
+  MediaStream get mediaStream => _mediaStream;

  /// internal use
  /// {@nodoc}
-  set mediaStream(MediaStream? stream) {
+  void setMediaStream(MediaStream stream) {
    _mediaStream = stream;
    notifyListeners();
  }

  @override
-  stop() {
-    super.stop();
-    _mediaStream?.dispose();
-    _mediaStream = null;
+  Future<void> stop() async {
+    await super.stop();
+    await _mediaStream.dispose();
+    // _mediaStream = null;
  }
 }