fix: android subtitle font

lib/mpv/player/player_native.dart

@@ -4,6 +4,8 @@ import 'dart:io' show Platform;
 
 import 'package:flutter/services.dart';
 
+import '../utils/android_font_loader.dart';
+
 import '../models/audio_device.dart';
 import '../models/audio_track.dart';
 import '../models/player_log.dart';
@@ -295,6 +297,11 @@ class PlayerNative implements Player {
         throw Exception('Failed to initialize player');
       }
 
+      // Configure subtitle fonts for Android libass support
+      if (Platform.isAndroid) {
+        await _configureAndroidSubtitleFonts();
+      }
+
       // Subscribe to MPV properties
       await _observeProperty('time-pos', 'double');
       await _observeProperty('duration', 'double');
@@ -321,6 +328,24 @@ class PlayerNative implements Player {
     });
   }
 
+  /// Configures subtitle fonts for Android libass support.
+  /// On Android, libass cannot access system fonts, so we need to provide
+  /// a font file from assets.
+  Future<void> _configureAndroidSubtitleFonts() async {
+    try {
+      final fontDir = await AndroidFontLoader.loadSubtitleFont();
+      if (fontDir != null) {
+        // Configure MPV to use the extracted font for libass
+        await setProperty('config', 'yes');
+        await setProperty('sub-fonts-dir', fontDir);
+        await setProperty('sub-font', AndroidFontLoader.fontName);
+      }
+    } catch (e) {
+      // Font configuration is not critical - continue without it
+      _errorController.add('Failed to configure subtitle fonts: $e');
+    }
+  }
+
   void _checkDisposed() {
     if (_disposed) {
       throw StateError('Player has been disposed');

lib/mpv/utils/android_font_loader.dart

@@ -0,0 +1,53 @@
+import 'dart:io';
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart';
+import 'package:path/path.dart' as path;
+import 'package:path_provider/path_provider.dart';
+
+/// Utility class for loading font assets on Android for libass subtitle rendering.
+///
+/// On Android, libass cannot access system fonts through fontconfig, so we need
+/// to extract font files from Flutter assets to the app's cache directory.
+class AndroidFontLoader {
+  static const String _fontAssetPath = 'assets/go-noto-current-regular.ttf';
+  static const String _fontName = 'Go Noto Current-Regular';
+
+  /// Loads the subtitle font from assets to the Android cache directory.
+  /// Returns the directory path containing the font file.
+  static Future<String?> loadSubtitleFont() async {
+    try {
+      // Get the app's cache directory
+      final cacheDir = await getTemporaryDirectory();
+      final fontDir = Directory(path.join(cacheDir.path, 'subtitle_fonts'));
+
+      // Create fonts directory if it doesn't exist
+      if (!await fontDir.exists()) {
+        await fontDir.create(recursive: true);
+      }
+
+      final fontFile = File(
+        path.join(fontDir.path, 'go-noto-current-regular.ttf'),
+      );
+
+      // Load font from assets and write to cache if it doesn't exist
+      if (!await fontFile.exists()) {
+        final fontData = await rootBundle.load(_fontAssetPath);
+        await fontFile.writeAsBytes(fontData.buffer.asUint8List());
+      }
+
+      return fontDir.path;
+    } catch (e) {
+      // Return null if font loading fails - libass will fall back gracefully
+      if (kDebugMode) {
+        debugPrint('Failed to load subtitle font: $e');
+      }
+      return null;
+    }
+  }
+
+  /// Returns the font name to be used with libass.
+  static String get fontName => _fontName;
+
+  /// Returns the font asset path.
+  static String get fontAssetPath => _fontAssetPath;
+}

lib/screens/video_player_screen.dart

@@ -254,8 +254,6 @@ class VideoPlayerScreenState extends State<VideoPlayerScreen>
       player = Player();
 
       await player!.setProperty('sub-ass', 'yes'); // Enable libass
-      await player!.setProperty('sub-fonts-dir', 'assets');
-      await player!.setProperty('sub-font', 'Go Noto Current-Regular');
       await player!.setProperty(
         'demuxer-max-bytes',
         bufferSizeBytes.toString(),