Minor refactoring (#808)

* Move transcription segment

* Use uuidv4 for visualizer id

Author: hiroshihorie

lib/livekit_client.dart

@@ -17,12 +17,14 @@ library livekit_client;
 
 export 'src/constants.dart';
 export 'src/core/room.dart';
-export 'src/events.dart';
-export 'src/exceptions.dart';
+export 'src/data_stream/stream_reader.dart';
+export 'src/data_stream/stream_writer.dart';
 export 'src/e2ee/e2ee_manager.dart';
 export 'src/e2ee/events.dart';
-export 'src/e2ee/options.dart';
 export 'src/e2ee/key_provider.dart';
+export 'src/e2ee/options.dart';
+export 'src/events.dart';
+export 'src/exceptions.dart';
 export 'src/extensions.dart' show WidgetsBindingCompatible;
 export 'src/hardware/hardware.dart';
 export 'src/livekit.dart';
@@ -36,28 +38,25 @@ export 'src/publication/local.dart';
 export 'src/publication/remote.dart';
 export 'src/publication/track_publication.dart';
 export 'src/support/platform.dart';
+export 'src/track/audio_visualizer.dart';
 export 'src/track/local/audio.dart';
 export 'src/track/local/local.dart';
 export 'src/track/local/video.dart';
 export 'src/track/options.dart';
+export 'src/track/processor.dart';
+export 'src/track/processor_native.dart'
+    if (dart.library.js_interop) 'src/track/processor_web.dart';
 export 'src/track/remote/audio.dart';
 export 'src/track/remote/remote.dart';
 export 'src/track/remote/video.dart';
 export 'src/track/track.dart';
-
-export 'src/track/processor.dart';
-export 'src/track/processor_native.dart'
-    if (dart.library.js_interop) 'src/track/processor_web.dart';
-
-export 'src/track/audio_visualizer.dart';
+export 'src/types/data_stream.dart';
 export 'src/types/other.dart';
 export 'src/types/participant_permissions.dart';
+export 'src/types/rpc.dart';
+export 'src/types/transcription_segment.dart';
 export 'src/types/video_dimensions.dart';
 export 'src/types/video_encoding.dart';
 export 'src/types/video_parameters.dart';
-export 'src/types/rpc.dart';
 export 'src/widgets/screen_select_dialog.dart';
 export 'src/widgets/video_track_renderer.dart';
-export 'src/data_stream/stream_reader.dart';
-export 'src/data_stream/stream_writer.dart';
-export 'src/types/data_stream.dart';

lib/src/core/room.dart

@@ -47,6 +47,7 @@ import '../track/track.dart';
 import '../types/data_stream.dart';
 import '../types/other.dart';
 import '../types/rpc.dart';
+import '../types/transcription_segment.dart';
 import '../utils.dart';
 import 'engine.dart';
 

lib/src/events.dart

@@ -12,7 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import 'package:livekit_client/src/track/processor.dart';
 import 'core/engine.dart';
 import 'core/room.dart';
 import 'core/signal_client.dart';
@@ -23,9 +22,11 @@ import 'publication/local.dart';
 import 'publication/remote.dart';
 import 'publication/track_publication.dart';
 import 'stats/stats.dart';
+import 'track/processor.dart';
 import 'track/track.dart';
 import 'types/other.dart';
 import 'types/participant_permissions.dart';
+import 'types/transcription_segment.dart';
 
 /// Base type for all LiveKit events.
 mixin LiveKitEvent {}
@@ -460,23 +461,6 @@ class ParticipantPermissionsUpdatedEvent with RoomEvent, ParticipantEvent {
       '(participant: ${participant}, permissions: ${permissions})';
 }
 
-class TranscriptionSegment {
-  final String id;
-  final String text;
-  final DateTime firstReceivedTime;
-  final DateTime lastReceivedTime;
-  final bool isFinal;
-  final String language;
-  const TranscriptionSegment({
-    required this.id,
-    required this.text,
-    required this.firstReceivedTime,
-    required this.lastReceivedTime,
-    required this.isFinal,
-    required this.language,
-  });
-}
-
 /// Transcription event received from the server.
 class TranscriptionEvent with RoomEvent, ParticipantEvent {
   final Participant participant;

lib/src/track/audio_visualizer.dart

@@ -2,9 +2,11 @@ import 'package:livekit_client/src/support/disposable.dart';
 import '../events.dart' show AudioVisualizerEvent;
 import '../managers/event.dart' show EventsEmittable;
 import 'local/local.dart' show AudioTrack;
+import 'package:uuid/uuid.dart' as uuid;
 
-import 'audio_visualizer_native.dart'
-    if (dart.library.js_interop) 'audio_visualizer_web.dart';
+import 'audio_visualizer_native.dart' if (dart.library.js_interop) 'audio_visualizer_web.dart';
+
+final _uuid = uuid.Uuid();
 
 class AudioVisualizerOptions {
   final bool centeredBands;
@@ -17,12 +19,13 @@ class AudioVisualizerOptions {
   });
 }
 
-abstract class AudioVisualizer extends DisposableChangeNotifier
-    with EventsEmittable<AudioVisualizerEvent> {
+abstract class AudioVisualizer extends DisposableChangeNotifier with EventsEmittable<AudioVisualizerEvent> {
+  // Unique Id for each visualizer
+  final String visualizerId = _uuid.v4();
+
   Future<void> start();
   Future<void> stop();
 }
 
-AudioVisualizer createVisualizer(AudioTrack track,
-        {AudioVisualizerOptions? options}) =>
+AudioVisualizer createVisualizer(AudioTrack track, {AudioVisualizerOptions? options}) =>
     createVisualizerImpl(track, options: options);

lib/src/track/audio_visualizer_native.dart

@@ -1,21 +1,22 @@
 import 'dart:async';
 
 import 'package:flutter/services.dart';
-
 import 'package:flutter_webrtc/flutter_webrtc.dart';
 
-import 'package:livekit_client/src/events.dart' show AudioVisualizerEvent;
-import 'package:livekit_client/src/track/local/local.dart';
+import '../events.dart' show AudioVisualizerEvent;
 import '../support/native.dart' show Native;
+import '../track/local/local.dart';
 import 'audio_visualizer.dart';
 
 class AudioVisualizerNative extends AudioVisualizer {
-  final String visualizerId = '${DateTime.now().millisecondsSinceEpoch}';
   EventChannel? _eventChannel;
   StreamSubscription? _streamSubscription;
+
   final AudioTrack? _audioTrack;
-  MediaStreamTrack get mediaStreamTrack => _audioTrack!.mediaStreamTrack;
   final AudioVisualizerOptions visualizerOptions;
+
+  MediaStreamTrack get mediaStreamTrack => _audioTrack!.mediaStreamTrack;
+
   AudioVisualizerNative(this._audioTrack, {required this.visualizerOptions}) {
     onDispose(() async {
       await events.dispose();
@@ -56,11 +57,6 @@ class AudioVisualizerNative extends AudioVisualizer {
     await Native.stopVisualizer(mediaStreamTrack.id!,
         visualizerId: visualizerId);
 
-    events.emit(AudioVisualizerEvent(
-      track: _audioTrack!,
-      event: [],
-    ));
-
     await _streamSubscription?.cancel();
     _streamSubscription = null;
     _eventChannel = null;

lib/src/types/transcription_segment.dart

@@ -0,0 +1,34 @@
+// Copyright 2025 LiveKit, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import 'package:flutter/foundation.dart';
+
+@immutable
+class TranscriptionSegment {
+  final String id;
+  final String text;
+  final DateTime firstReceivedTime;
+  final DateTime lastReceivedTime;
+  final bool isFinal;
+  final String language;
+
+  const TranscriptionSegment({
+    required this.id,
+    required this.text,
+    required this.firstReceivedTime,
+    required this.lastReceivedTime,
+    required this.isFinal,
+    required this.language,
+  });
+}