Reuse transceivers (#24)

* protocol 4

* default to v4

* mediaStreamTrack.enabled

* track start

* private constructor

* remote audio/video tracks

* log sdp

* organize imports

lib/src/track/audio_track.dart

@@ -8,7 +8,7 @@ import 'package:synchronized/synchronized.dart' as sync;
 import '../logger.dart';
 import '../proto/livekit_models.pb.dart' as lk_models;
 import '../support/native_audio.dart';
-import '_audio_api.dart' if (dart.library.html) '_audio_html.dart' as audio;
+
 import 'local_audio_track.dart';
 import 'track.dart';
 
@@ -22,7 +22,7 @@ enum AudioTrackState {
 typedef ConfigureNativeAudioFunc = Future<NativeAudioConfiguration> Function(
     AudioTrackState state);
 
-class AudioTrack extends Track {
+abstract class AudioTrack extends Track {
   // it's possible to set custom function here to customize audio session configuration
   static ConfigureNativeAudioFunc nativeAudioConfigurationForAudioTrackState =
       defaultNativeAudioConfigurationFunc;
@@ -50,10 +50,6 @@ class AudioTrack extends Track {
   Future<bool> start() async {
     final didStart = await super.start();
     if (didStart) {
-      if (this is! LocalAudioTrack) {
-        audio.startAudio(getCid(), mediaStreamTrack);
-      }
-
       // update counter
       await _trackCounterLock.synchronized(() async {
         if (this is LocalAudioTrack) {
@@ -64,7 +60,6 @@ class AudioTrack extends Track {
         await _onAudioTrackCountDidChange();
       });
     }
-
     return didStart;
   }
 
@@ -72,10 +67,6 @@ class AudioTrack extends Track {
   Future<bool> stop() async {
     final didStop = await super.stop();
     if (didStop) {
-      await mediaStream?.dispose();
-      mediaStream = null;
-      audio.stopAudio(getCid());
-
       // update counter
       await _trackCounterLock.synchronized(() async {
         if (this is LocalAudioTrack) {
@@ -86,7 +77,6 @@ class AudioTrack extends Track {
         await _onAudioTrackCountDidChange();
       });
     }
-
     return didStop;
   }
 

lib/src/track/local_audio_track.dart

@@ -7,7 +7,8 @@ import 'audio_track.dart';
 import 'options.dart';
 
 class LocalAudioTrack extends AudioTrack {
-  LocalAudioTrack(
+  // private constructor
+  LocalAudioTrack._(
     String name,
     rtc.MediaStreamTrack track,
     rtc.MediaStream stream,
@@ -29,6 +30,15 @@ class LocalAudioTrack extends AudioTrack {
 
     if (stream.getAudioTracks().isEmpty) throw TrackCreateException();
 
-    return LocalAudioTrack('', stream.getAudioTracks().first, stream);
+    return LocalAudioTrack._('', stream.getAudioTracks().first, stream);
+  }
+
+  @override
+  Future<bool> stop() async {
+    final didStop = await super.stop();
+    if (didStop) {
+      await mediaStreamTrack.stop();
+    }
+    return didStop;
   }
 }

lib/src/track/local_video_track.dart

@@ -92,6 +92,15 @@ class LocalVideoTrack extends VideoTrack {
     if (stream.getVideoTracks().isEmpty) throw TrackCreateException();
     return stream;
   }
+
+  @override
+  Future<bool> stop() async {
+    final didStop = await super.stop();
+    if (didStop) {
+      await mediaStreamTrack.stop();
+    }
+    return didStop;
+  }
 }
 
 //

lib/src/track/remote_audio_track.dart

@@ -0,0 +1,34 @@
+import 'package:flutter_webrtc/flutter_webrtc.dart' as rtc;
+import '_audio_api.dart' if (dart.library.html) '_audio_html.dart' as audio;
+import 'audio_track.dart';
+
+class RemoteAudioTrack extends AudioTrack {
+  //
+  RemoteAudioTrack(
+    String name,
+    rtc.MediaStreamTrack track,
+    rtc.MediaStream stream,
+  ) : super(name, track, stream);
+
+  @override
+  Future<bool> start() async {
+    final didStart = await super.start();
+    if (didStart) {
+      // web support
+      audio.startAudio(getCid(), mediaStreamTrack);
+      await enable();
+    }
+    return didStart;
+  }
+
+  @override
+  Future<bool> stop() async {
+    final didStop = await super.stop();
+    if (didStop) {
+      // web support
+      audio.stopAudio(getCid());
+      await disable();
+    }
+    return didStop;
+  }
+}

lib/src/track/remote_video_track.dart

@@ -0,0 +1,29 @@
+import 'package:flutter_webrtc/flutter_webrtc.dart' as rtc;
+import 'package:livekit_client/src/track/video_track.dart';
+
+class RemoteVideoTrack extends VideoTrack {
+  //
+  RemoteVideoTrack(
+    String name,
+    rtc.MediaStreamTrack mediaTrack,
+    rtc.MediaStream stream,
+  ) : super(name, mediaTrack, stream);
+
+  @override
+  Future<bool> start() async {
+    final didStart = await super.start();
+    if (didStart) {
+      await enable();
+    }
+    return didStart;
+  }
+
+  @override
+  Future<bool> stop() async {
+    final didStop = await super.stop();
+    if (didStop) {
+      await disable();
+    }
+    return didStop;
+  }
+}

lib/src/track/track.dart

@@ -76,6 +76,8 @@ abstract class Track extends DisposableChangeNotifier
       return false;
     }
 
+    logger.fine('Track.start()');
+
     _active = true;
     return true;
   }
@@ -88,13 +90,29 @@ abstract class Track extends DisposableChangeNotifier
       return false;
     }
 
-    try {
-      await mediaStreamTrack.stop();
-    } catch (_) {
-      logger.warning('[$objectId] rtc.mediaStreamTrack.stop() did throw ${_}');
-    }
+    logger.fine('Track.stop()');
 
     _active = false;
     return true;
   }
+
+  Future<void> enable() async {
+    logger.fine('Track.enable()');
+    try {
+      mediaStreamTrack.enabled = true;
+    } catch (_) {
+      logger.warning(
+          '[$objectId] set rtc.mediaStreamTrack.enabled did throw ${_}');
+    }
+  }
+
+  Future<void> disable() async {
+    logger.fine('Track.disable()');
+    try {
+      mediaStreamTrack.enabled = false;
+    } catch (_) {
+      logger.warning(
+          '[$objectId] set rtc.mediaStreamTrack.enabled did throw ${_}');
+    }
+  }
 }

lib/src/track/video_track.dart

@@ -5,7 +5,7 @@ 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 {
+abstract class VideoTrack extends Track {
   rtc.MediaStream _mediaStream;
 
   VideoTrack(