Strophe 活字

Strophe is a high-performance, professional-grade subtitle authoring tool built natively for Apple platforms. It combines modern Liquid Glass design aesthetics with industrial-grade audio/video processing technology, delivering an ultra-smooth subtitling experience for creators.

✨ Core Features

Video Playback

• FFmpeg-Powered Engine: Full support for formats not natively supported by AVFoundation, including MKV, WebM, FLV, AVI, and more
• VideoToolbox Hardware Acceleration: Zero-copy GPU decoding for H.264/H.265 with minimal CPU usage
• Metal Rendering: High-performance GPU-based BT.709 color conversion for accurate video display
• Cross-Platform: Native support for both macOS and iOS

Waveform & Timeline

• High-Performance Waveform Engine: Real-time dual-layer rendering of Peak (transient) and RMS (energy envelope) using Accelerate framework and vDSP
• ProMotion Full Frame Rate: Interpolation algorithms and TimelineView-driven rendering supporting 120Hz displays
• Logic Pro-Style Interactions:
  • Smart Zoom: Option + Scroll for rapid zooming with automatic ruler precision adjustment
  • Professional Playhead: Draggable magnetic playhead with real-time scrubbing
  • Auto-Follow: Automatic centering during playback to maintain creative focus

Subtitle Editing

• J/K Slapping Mode: Professional rhythm-based subtitle timing using J and K keys
• Selection & Creation Tools: Switch between selection mode and creation mode for efficient workflow
• Frame-Accurate Timing: Automatic frame snapping based on video frame rate
• Overlap Detection: Visual indicators for overlapping subtitle blocks
• Soft Subtitle Preview: Real-time preview of embedded subtitles

Project Management

• .strophe Project Format: Save and restore complete project state including media references
• Auto-Save: Automatic project saving every 30 seconds
• Export: Generate SRT subtitle files from your projects

Modern Design

• Liquid Glass UI (macOS 26+ / iOS 26+): Beautiful translucent materials with vibrant depth effects
• Legacy Support: Clean fallback styling for older macOS/iOS versions
• Dark Mode: Full support for system appearance preferences
• Keyboard Shortcuts: Comprehensive keyboard shortcuts for power users

🚀 Quick Start

1. Import Media: Drag and drop a video or audio file into the application window
2. Timeline Navigation:
   • Option + Scroll: Zoom timeline in/out
   • Click waveform: Jump to position
   • Drag playhead: Fine-grained audio preview
3. Subtitle Editing:
   • Use Selection Tool (V) to select and move subtitle blocks
   • Use Creation Tool (D) to create new subtitle blocks
   • Press J/K keys for rhythm-based timing (slapping mode)
4. Export: Save your project or export to SRT format

⌨️ Keyboard Shortcuts

Action	Shortcut
Play/Pause	Space
Selection Tool	V
Creation Tool	D
Soft Subtitle Preview	⌥S
Skip Forward 5s	⌘→
Skip Backward 5s	⌘←
Save Project	⌘S
Save Project As	⇧⌘S

🛠️ Technical Architecture

• Language: Swift 6 (Strict Concurrency)
• Frameworks: SwiftUI, AVFoundation, Metal, Accelerate
• Video Engine: FFmpeg (via Libav*) with VideoToolbox integration
• Audio Engine: AVAudioEngine with real-time resampling
• Rendering: Metal + Canvas with GPU DrawingGroup Cache
• Math Engine: Accelerate (vDSP) for waveform processing

📋 Supported Formats

Video Containers

• MP4, MOV, M4V (via AVFoundation)
• MKV, WebM, FLV, AVI, RMVB (via FFmpeg)

Audio Formats

• AAC, MP3, WAV, FLAC, Opus, and more

Subtitle Formats

• Import: Plain text, SRT
• Export: SRT

📄 License

This project is source available under the Functional Source License.