🎬 Dual video player
Load and compare Video 1 and Video 2 side by side, Zoom-style large/small side layout, stacked, focus, or cinema layout.
📁 Flexible file loading
Load video, audio, and subtitle files directly from the browser. Recent sessions are kept on the home screen.
💬 Subtitle control
Turn subtitles on/off for V1 or V2, change size, colour, background opacity, position, and delay.
🌐 Translate tab
Manage translated subtitle display, translation colour, and translation size in one dedicated tab.
📝 Timestamp notes
Add notes at the current timestamp, mark them by colour, preview note text on the dot, and jump back by clicking the dot.
⬇ Note export
Export notes as TXT, Markdown, CSV, or JSON, or copy all notes directly.
↺ A-B loop
Set A and B points, then loop only that section for repeated listening or detailed review.
🎚 Video tab
Adjust brightness, link or separate V1/V2 brightness, hide/show each video, and control V2 sync offset.
🔤 Font setting
Change the interface font and subtitle font separately from the Settings panel.
⏱ Pomodoro timer
Show a compact Focus or Break timer beside the Douple logo. It can automatically move from Focus to Break based on the selected Pomodoro pattern.
🔊 Audio mixer
Control master volume and separate volume or mute state for V1, V2, and external audio.
📷 Extra tools
Use screenshot, Picture-in-Picture, fullscreen, dark/light mode, and playback speed controls from the bottom bar.
💾 Auto-save session
Position, notes, layout, speed, brightness, subtitle offset, and video visibility are saved automatically.
🔎 Note search
Open the compact search icon in Notes to filter notes without taking extra space.
🎯 Focus mode
Enter a cleaner fullscreen review mode with panels and bottom controls hidden.
⌨ Shortcut editor
Change the main keyboard shortcuts from Settings, including quick layout keys.
🧩 Study subtitle tools
Generate a local summary and quiz from the uploaded VTT/SRT subtitle. Configure Summary, Quiz, subtitle cleaner, question count, and difficulty from Settings → Study. No API key is required.