feat: Support for capturing audio for chrome tab. (#158)

* feat: Support for capturing audio for chrome tab.

* Update code comments.

lib/src/participant/local.dart

@@ -15,6 +15,7 @@ import '../publication/local.dart';
 import '../track/local/audio.dart';
 import '../track/local/local.dart';
 import '../track/local/video.dart';
+import '../track/options.dart';
 import '../types/other.dart';
 import '../types/participant_permissions.dart';
 import '../types/video_dimensions.dart';
@@ -283,14 +284,17 @@ class LocalParticipant extends Participant<LocalTrackPublication> {
   }
 
   /// Shortcut for publishing a [TrackSource.screenShareVideo]
-  Future<LocalTrackPublication?> setScreenShareEnabled(bool enabled) async {
-    return setSourceEnabled(TrackSource.screenShareVideo, enabled);
+  Future<LocalTrackPublication?> setScreenShareEnabled(bool enabled,
+      {bool? captureScreenAudio}) async {
+    return setSourceEnabled(TrackSource.screenShareVideo, enabled,
+        captureScreenAudio: captureScreenAudio);
   }
 
   /// A convenience method to publish a track for a specific [TrackSource].
   /// This is the recommended method to publish tracks.
   Future<LocalTrackPublication?> setSourceEnabled(
-      TrackSource source, bool enabled) async {
+      TrackSource source, bool enabled,
+      {bool? captureScreenAudio}) async {
     logger.fine('setSourceEnabled(source: $source, enabled: $enabled)');
     final publication = getTrackPublicationBySource(source);
     if (publication != null) {
@@ -314,6 +318,25 @@ class LocalParticipant extends Participant<LocalTrackPublication> {
             room.roomOptions.defaultAudioCaptureOptions);
         return await publishAudioTrack(track);
       } else if (source == TrackSource.screenShareVideo) {
+        /// When capturing chrome table audio, we can't capture audio/video
+        /// track separately, it has to be returned once in getDisplayMedia,
+        /// so we publish it twice here, but only return videoTrack to user.
+        if (captureScreenAudio != null) {
+          final tracks = await LocalVideoTrack.createScreenShareTracksWithAudio(
+              ScreenShareCaptureOptions(
+                  captureScreenAudio: captureScreenAudio));
+          LocalTrackPublication<LocalVideoTrack>? publication;
+          for (final track in tracks) {
+            if (track is LocalVideoTrack) {
+              publication = await publishVideoTrack(track);
+            } else if (track is LocalAudioTrack) {
+              await publishAudioTrack(track);
+            }
+          }
+
+          /// just return the video track publication
+          return publication;
+        }
         final track = await LocalVideoTrack.createScreenShareTrack(
             room.roomOptions.defaultScreenShareCaptureOptions);
         return await publishVideoTrack(track);

lib/src/track/local/audio.dart

@@ -1,6 +1,7 @@
 import 'dart:async';
 
 import 'package:flutter_webrtc/flutter_webrtc.dart' as rtc;
+import 'package:meta/meta.dart';
 
 import '../../proto/livekit_models.pb.dart' as lk_models;
 import '../../types/other.dart';
@@ -15,7 +16,8 @@ class LocalAudioTrack extends LocalTrack
   covariant AudioCaptureOptions currentOptions;
 
   // private constructor
-  LocalAudioTrack._(
+  @internal
+  LocalAudioTrack(
     String name,
     TrackSource source,
     rtc.MediaStream stream,
@@ -36,7 +38,7 @@ class LocalAudioTrack extends LocalTrack
     options ??= const AudioCaptureOptions();
     final stream = await LocalTrack.createStream(options);
 
-    return LocalAudioTrack._(
+    return LocalAudioTrack(
       '',
       TrackSource.microphone,
       stream,

lib/src/track/local/local.dart

@@ -119,7 +119,9 @@ abstract class LocalTrack extends Track {
     final constraints = <String, dynamic>{
       'audio': options is AudioCaptureOptions
           ? options.toMediaConstraintsMap()
-          : false,
+          : options is ScreenShareCaptureOptions
+              ? (options).captureScreenAudio
+              : false,
       'video': options is VideoCaptureOptions
           ? options.toMediaConstraintsMap()
           : false,

lib/src/track/local/video.dart

@@ -5,6 +5,7 @@ import '../../proto/livekit_models.pb.dart' as lk_models;
 import '../../types/other.dart';
 import '../options.dart';
 import '../track.dart';
+import 'audio.dart';
 import 'local.dart';
 
 /// A video track from the local device. Use static methods in this class to create
@@ -63,6 +64,39 @@ class LocalVideoTrack extends LocalTrack with VideoTrack {
       options,
     );
   }
+
+  /// Creates a LocalTracks(audio/video) from the display.
+  ///
+  /// The current API is mainly used to capture audio when chrome captures tab,
+  /// but in the future it can also be used for flutter native to open audio
+  /// capture device when capturing screen
+  static Future<List<LocalTrack>> createScreenShareTracksWithAudio([
+    ScreenShareCaptureOptions? options,
+  ]) async {
+    options ??= const ScreenShareCaptureOptions(captureScreenAudio: true);
+
+    final stream = await LocalTrack.createStream(options);
+
+    List<LocalTrack> tracks = [
+      LocalVideoTrack._(
+        Track.screenShareName,
+        TrackSource.screenShareVideo,
+        stream,
+        stream.getVideoTracks().first,
+        options,
+      )
+    ];
+
+    if (stream.getAudioTracks().isNotEmpty) {
+      tracks.add(LocalAudioTrack(
+          Track.screenShareName,
+          TrackSource.screenShareAudio,
+          stream,
+          stream.getAudioTracks().first,
+          const AudioCaptureOptions()));
+    }
+    return tracks;
+  }
 }
 
 //

lib/src/track/options.dart

@@ -82,8 +82,11 @@ class ScreenShareCaptureOptions extends VideoCaptureOptions {
   /// See instructions on how to setup your Broadcast Extension here:
   /// https://github.com/flutter-webrtc/flutter-webrtc/wiki/iOS-Screen-Sharing#broadcast-extension-quick-setup
   final bool useiOSBroadcastExtension;
+  final bool captureScreenAudio;
+
   const ScreenShareCaptureOptions({
     this.useiOSBroadcastExtension = false,
+    this.captureScreenAudio = false,
     String? sourceId,
     double? maxFrameRate,
     VideoParameters params = VideoParametersPresets.screenShareH720FPS15,
@@ -91,6 +94,7 @@ class ScreenShareCaptureOptions extends VideoCaptureOptions {
 
   ScreenShareCaptureOptions.from(
       {this.useiOSBroadcastExtension = false,
+      this.captureScreenAudio = false,
       required VideoCaptureOptions captureOptions})
       : super(params: captureOptions.params);