Desktop Features

Desktop (Electron) specific features and architecture.

🖥️ Complete Desktop Workflow (Download-Create-Encode)

Desktop-exclusive complete workflow from source acquisition to final output:

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🚀 Full-Auto End-to-End Mode

This is an Electron-exclusive core feature, coordinating Main Process (resource scheduling) and Renderer Process (AI computation) via IPC for "one-click hardsub".

Cross-Process Interaction Architecture

Key IPC Channels

Channel	Direction	Payload	Purpose
end-to-end:start	Renderer -> Main	EndToEndConfig	Start full-auto task
end-to-end:generate-subtitles	Main -> Renderer	path, config	Main ready, request generation
end-to-end:subtitle-result	Renderer -> Main	SubtitleItem[]	Generation complete, return result
end-to-end:progress	Main -> Renderer	stage, progress	Real-time progress sync

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🛰️ Custom Media Protocol

To bypass browser security restrictions (CSP, sandbox) and support large file streaming:

local-video:// Protocol

• Location: electron/main.ts
• Core Permissions: standard, secure, stream, supportFetchAPI, bypassCSP
• Key Tech - Tailing Reader: Supports reading "growing files" (transcoding in progress). Uses polling to read new data FFmpeg is writing to disk.

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📺 Video Preview & Cache Strategy

System uses fragmented MP4 (fMP4) transcoding strategy for progressive playback during transcoding.

Architecture Overview

Component	Location	Function
VideoPlayerPreview	src/components/editor/	React player, ASS subtitle overlay
useVideoPreview	src/hooks/	Transcode progress, video source, state
videoPreviewTranscoder	electron/services/	FFmpeg transcoding, GPU accel, caching

Flow Diagram

Core Features

Feature	Description
Progressive Play	Play before transcoding completes via fMP4 + Tailing
GPU Acceleration	Auto-detect NVENC/QSV/VCE for faster transcoding
Format Detection	Skip transcoding for browser-compatible formats
WYSIWYG Subtitles	Real-time ASS rendering with assjs
Float/Dock Mode	Resizable floating window or docked panel

Cache Lifecycle

• Location: User data directory (/preview_cache/)
• Limit: Auto-enforce total size limit (default 3GB)
• Cleanup: Auto-detect on startup (oldest first), UI manual cleanup

IPC Channels

Channel	Direction	Payload	Purpose
transcode-for-preview	Renderer → Main	{ filePath }	Request video transcoding
transcode-start	Main → Renderer	{ outputPath, duration }	Transcoding started
transcode-progress	Main → Renderer	{ percent, transcodedDuration }	Real-time progress
cache:get-size	Renderer → Main	-	Get preview cache size
cache:clear	Renderer → Main	-	Clear preview cache

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🔧 Desktop Service Modules

File	Description
main.ts	Electron main process, window & IPC
preload.ts	Preload script, secure Node.js API exposure
logger.ts	Unified logging, file rotation, JSON view
utils/paths.ts	Portable path resolution, exe-relative storage
services/localWhisper.ts	Local Whisper, GPU detection
services/ffmpegAudioExtractor.ts	FFmpeg audio extraction
services/ytdlp.ts	Video download (YouTube/Bilibili)
services/videoCompressor.ts	Video encoding, NVENC/QSV/AMF acceleration
services/videoPreviewTranscoder.ts	Preview transcoding, fMP4, caching
services/endToEndPipeline.ts	Full automation pipeline
services/storage.ts	Portable storage, exe-relative config/logs