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Playback

Playback in Litefin is handled by a sophisticated triple-backend system that prioritizes hardware acceleration.

Advanced Player Core

The player is implemented as a standalone sub-project under src/player/ with two major modules:

  • core/ (11 files): Low-level playback engines and subtitle rendering.
  • osd/ (19 files): On-Screen Display menus and controllers for user interaction.

Platform Players

  • Tizen AVPlay (src/player/core/TizenAVPlayer.js): The primary backend for Samsung TVs. Utilizes native hardware decoding via webapis.avplay with:
    • Buffer Tuning: Hardware-level buffer thresholds (byte-based and property-based).
    • Trickplay: Support for previewing thumbnails during seeking.
    • Rewind Buffer: A 10-second rewind buffer for direct streams to improve responsiveness.
  • webOS Player (src/player/core/WebOSPlayer.js): Dedicated hardware integration for LG webOS devices using webOS video APIs.
  • HTML5 Web Player (src/player/core/HtmlVideoPlayer.js): A fallback renderer for environments where native hardware APIs are unavailable or unsupported.

JellyfinPlayer

The main player controller (src/player/core/JellyfinPlayer.js) orchestrates all platform players. It handles:

  • Player backend selection based on platform and content type.
  • Playback reporting (start/progress/stop) to the Jellyfin server.
  • Quality switching, seeking, and trickplay.
  • Integration with SyncPlay for synchronized group playback.

Subtitle Management

Subtitles are a core focus of the playback experience:

  • SubtitleManager (src/player/core/SubtitleManager.js): Centralizes tracking and rendering of all subtitle formats with format detection and delivery strategy.
  • ASS/SSA Rendering: Uses LibassWasmRenderer — libass compiled to WebAssembly (via @jellyfin/libass-wasm). Replaces the older libjass approach. Includes Tizen-targeted optimizations for skew, vertical spacing, and "staircase" layouts. A legacy variant (LibassWasmRenderer.legacy.js) is available for older Tizen builds.
  • PGS Support (src/player/core/PGSRenderer.js): Native rendering support for image-based PGS subtitles (via libpgs).
  • ASS Renderer (src/player/core/ASSRenderer.js): Alternative pure-JS ASS rendering using libjass for environments where WebAssembly is unavailable.
  • External Delivery: Logic to force external subtitle delivery when transcoding to avoid playback out-of-bounds errors on certain hardware.
  • Subtitle Parsing (src/player/core/SubtitleParser.js): Parses and normalizes subtitle streams for consistent rendering.

On-Screen Display (OSD)

The OSD subsystem (src/player/osd/) provides 19 modular menus managed by OSDController.js:

Menu File Purpose
Chapters ChaptersModal.js Chapter navigation
Quality QualityMenu.js Bitrate/resolution switching
Tracks TrackMenu.js Audio/subtitle track selection
Playback Mode PlaybackModeMenu.js Shuffle, repeat
Playback Speed PlaybackSpeedMenu.js Speed control (0.5x–2x)
Aspect Ratio AspectRatioMenu.js Force aspect ratio
Subtitle Offset SubtitleOffset.js Subtitle timing offset
Subtitle Quick Settings SubtitleQuickSettings.js Font size, color, position
Lyrics LyricsModal.js Synchronized lyrics view
Queue QueueModal.js Now playing queue
Up Next UpNextDialog.js Auto-play next episode countdown
Playback Info PlaybackInfo.js Transcode details, codec info
Settings SettingsMenu.js Player settings
SyncPlay Notifications SyncPlayNotification.js Group playback events
Trickplay TrickplayManager.js Seek thumbnails
Description DescriptionModal.js Item description/overview
Repeat Mode RepeatModeMenu.js Repeat off/all/one
Base Menu BaseMenu.js Abstract base for OSD menus

Transcoding & Negotiation

The Device Profile system (src/api/DeviceProfile.js and src/api/profiles/) negotiates capabilities with the Jellyfin server. It provides specific profiles for:

  • 4K / HEVC / HDR10+ support.
  • Dolby Vision (DoVi) profiles (7/8) with HDR10 fallback logic.
  • Audio codec constraints (e.g., forcing transcoding for unsupported DTS or EAC3 streams).
  • Real-time quality switching and bit-rate limitation management.