flutter_ass_player #

Cross-platform Flutter video player with native libass rendering and a bundled JASSUB WebAssembly renderer for Advanced SubStation Alpha (.ass) subtitles.

Installation #

Add the package to your application:

dependencies:
  flutter_ass_player: ^0.1.0

The package depends on media_kit and includes its video libraries. Follow the platform setup in the media_kit installation guide when your target requires additional configuration.

Basic usage #

import 'package:flutter_ass_player/flutter_ass_player.dart';

final controller = AssPlayerController();

AssVideoPlayer(
  source: 'https://example.com/video.mp4',
  assContent: assDocument,
  controller: controller,
  configuration: const AssPlayerConfiguration(
    autoPlay: true,
    webFontAssets: <String>[
      'assets/fonts/NotoSans-Regular.ttf',
    ],
  ),
);

The assContent value must be a complete ASS document, not a file path. It can be replaced while the player is active:

await controller.setAssContent(updatedAssDocument);
await controller.seek(const Duration(seconds: 5));
await controller.playRange(
  const Duration(seconds: 5),
  const Duration(seconds: 10),
);

Dispose a controller created by your application when it is no longer needed. Controllers created internally by AssVideoPlayer are disposed automatically.

Fonts #

Declare every custom font used by an ASS document in the host application's pubspec.yaml:

flutter:
  assets:
    - assets/fonts/NotoSans-Regular.ttf

Pass those paths through webFontAssets for web rendering. On Android, libass cannot discover system fonts, so also set the TTF asset and its actual family name:

const AssPlayerConfiguration(
  nativeFontAsset: 'assets/fonts/NotoSans-Regular.ttf',
  nativeFontFamily: 'Noto Sans',
  webFontAssets: <String>['assets/fonts/NotoSans-Regular.ttf'],
);

nativeFontAsset and nativeFontFamily must either both be set or both be omitted.

Web deployment #

The bundled renderer works without cross-origin isolation. To enable browser features that use shared memory and multiple threads, send these response headers for the application and its assets:

Cross-Origin-Opener-Policy: same-origin
Cross-Origin-Embedder-Policy: require-corp

Remote videos and fonts must permit access from the application's origin.

Licensing #

Original package code is available under the MIT License. The web runtime redistributes JASSUB 1.7.17 and its dependencies under their respective licenses. See third-party notices before distributing an application containing the web assets.