Vayou

A native desktop video player built on libmpv, with a Svelte 5 frontend and a Rust + Tauri 2 backend. Optimized for fast startup, low memory footprint, and a small binary.

Features

Playback

• Play / pause / seek (relative & absolute)
• Speed control from 0.25x to 4x with a quick-pick dropdown
• Frame-by-frame stepping (forward and backward)
• Screenshot capture
• A–B loop (set point A → point B → clear)
• Chapter navigation
• Open from URL (network streams)
• Resume position across sessions (top 20 recent files)
• Sleep timer

Audio

• Multi-track audio with per-file persistence
• 10-band equalizer
• Loudness normalization (dynaudnorm)
• Volume boost up to 200%
• Audio delay adjustment

Subtitles

• Multi-track embedded + external (SRT / ASS / SSA)
• Per-file selection persistence
• Customizable style: font, size, color, border color, border size, bold, vertical position
• OpenSubtitles integration: search, preview, download
• Automatic translation of the active subtitle into 12 languages, preserving ASS styling. Falls back to SRT for non-styled sources. Source-track switching mid-playback re-translates from the new track.
• Subtitle delay adjustment

Video

• Brightness / contrast / saturation
• Aspect ratio cycling (auto, 16:9, 4:3, 21:9, 2.35:1)
• Software deinterlace toggle
• Zoom and pan (numpad-controlled)

Window & UX

• Frameless transparent window with custom title bar
• Always-on-top toggle
• Drag & drop files onto the window to play
• Custom keybindings (rebindable from settings)
• 13 UI languages: English, Português, Español, Français, Deutsch, Italiano, 日本語, 한국어, 中文, Русский, العربية, हिन्दी
• File associations registered for 11 video and 8 audio extensions, each with its own per-extension icon

Screenshots

Building from source

Prerequisites

• Rust (stable, 2021 edition or later) — install via rustup
• Node.js 18+ and pnpm 8+
• Microsoft Visual Studio Build Tools with the Desktop development with C++ workload (Windows only)
• NSIS (auto-installed by Tauri on first build)

Native dependencies

libmpv-2.dll and ffmpeg.exe are not committed to the repository (they total ~220 MB and exceed GitHub's per-file limit). The published installer already bundles them — only contributors building from source need to fetch them manually.

Download both into src-tauri/binaries/:

After placing the two files, the standard pnpm install && pnpm tauri dev flow works.

Development

pnpm install
pnpm tauri dev

The dev build hot-reloads the frontend on save. Rust code changes trigger a full rebuild.

Release build

pnpm tauri build

Outputs:

• Standalone executable: src-tauri/target/release/vayou-desktop.exe (~5 MB after LTO + strip)
• NSIS installer: src-tauri/target/release/bundle/nsis/Vayou_<version>_x64-setup.exe

The release profile uses lto = true, codegen-units = 1, opt-level = "s", and strip = true for the smallest possible binary at the cost of compile time.

Architecture

src/                       # SvelteKit frontend (adapter-static)
├── lib/
│   ├── bindings/          # Typed wrappers around Tauri invoke() per domain
│   ├── components/        # UI components (TitleBar, VideoControls, panels…)
│   ├── i18n/              # 13 locale files + reactive t() helper
│   ├── stores/            # Svelte 5 runes-based stores ($state classes)
│   └── utils/             # Pure helpers (time format, lang names)
└── routes/+page.svelte    # Single-route shell

src-tauri/
├── src/
│   ├── mpv/               # libmpv FFI wrapper (libloading-based)
│   ├── services/          # Pure logic: playback, tracks, settings, translate, …
│   ├── commands/          # Thin #[tauri::command] handlers — delegate to services
│   ├── state/             # MpvState + AppState (settings, current file, pending resume)
│   └── error.rs           # AppError / MpvError via thiserror
├── binaries/              # libmpv-2.dll, ffmpeg.exe (bundled)
├── icons/                 # App icons + per-extension association icons
└── installer-hooks.nsh    # NSIS hook overriding per-extension DefaultIcon

State flow: events flow upward (mpv:* events emitted from a dedicated event-loop thread); commands flow downward (frontend → command → service → mpv). UI never touches mpv directly.

libmpv integration: loaded dynamically at runtime via libloading from binaries/libmpv-2.dll. The native window's HWND is passed to mpv via the wid property, so mpv renders directly into the Tauri window with zero copy.

Subtitle translation: extracted via ffmpeg, chunked by character count, fanned out through a tokio::sync::Semaphore (max 8 concurrent requests) to avoid rate-limiting, then re-assembled and added to mpv as an external subtitle track. A monotonic run-id cancels stale translations when the user switches language mid-flight.

Keyboard shortcuts

All shortcuts are rebindable from Settings → Shortcuts. Defaults:

File associations

The installer registers Vayou as a handler for the following extensions, each with a custom colored icon:

• Video: .mp4 .mkv .avi .mov .webm .flv .wmv .m4v .ts .mpg .mpeg
• Audio: .mp3 .flac .ogg .wav .aac .wma .m4a .opus

Files associated with Vayou can be opened via Open With in Explorer, double-click (when set as default), or by passing the path as a command-line argument.

Configuration & data location

• Settings: %APPDATA%\Vayou\config.json
• Cached translations: %TEMP%\vayou-translate\ (cleared by the OS periodically)
• Logs: stdout (set RUST_LOG=vayou=debug for verbose output)

Third-party components

Vayou bundles or talks to the following third-party software and services. Their licenses and terms apply to the redistributed binaries / network usage and are independent of this project's MIT license:

License

MIT — see the LICENSE file for the full text.