Video Subtitle Download

Extract subtitles/transcripts from video URLs and save them as local text files.

Supported platforms: YouTube, Bilibili, Twitter/X, Vimeo, TikTok, and all other platforms supported by yt-dlp.

Input Video URL: $ARGUMENTS

Step 1: Verify Tool Availability

1. Check yt-dlp installation:

   which yt-dlp
   

   • If yt-dlp is found, proceed to Step 2.
   • If yt-dlp is NOT found, notify user: "yt-dlp is not installed. Please install it first: brew install yt-dlp or pip install yt-dlp" Then STOP execution.

Step 2: Get Video Information

1. Get video title:

   yt-dlp --get-title "[VIDEO_URL]"
   

   • If this fails with authentication error, try with cookies:

     yt-dlp --cookies-from-browser chrome --get-title "[VIDEO_URL]"
     

   • If browser cookie extraction fails, ask user to specify their browser (firefox, safari, edge) and retry.

2. Store the video title for file naming (sanitize special characters).

Step 3: Download Subtitles

1. Attempt subtitle download with language priority (Chinese first, then English):

   yt-dlp --write-auto-sub --write-sub --sub-lang zh-Hans,zh-Hant,zh,en --skip-download --sub-format vtt --output "<Video Title>.%(ext)s" "[VIDEO_URL]"
   

   • For platforms requiring authentication (YouTube, Bilibili, etc.), add cookies:

     yt-dlp --cookies-from-browser chrome --write-auto-sub --write-sub --sub-lang zh-Hans,zh-Hant,zh,en --skip-download --sub-format vtt --output "<Video Title>.%(ext)s" "[VIDEO_URL]"
     

2. Handle platform-specific cases:

   • Bilibili: May require --cookies-from-browser for member-only videos
   • YouTube: Use --write-auto-sub for auto-generated subtitles
   • Twitter/X: Subtitles may not be available for all videos

3. Verify download:

   • Check if .vtt or .srt file was created
   • If no subtitle file found, inform user that subtitles are not available for this video

Step 4: Convert to Plain Text

1. Read the downloaded subtitle file (.vtt or .srt)

2. Extract and clean content:

   • Remove timing information
   • Remove duplicate lines
   • Remove formatting tags
   • Keep only the actual transcript text

3. Format output:

   • Each line: [Timestamp] Text content
   • Or plain text without timestamps if user prefers

Step 5: Detect Language and Save

1. Detect source language:

   • From subtitle filename: Check the downloaded file extension
     • .zh-Hans.vtt, .zh-Hant.vtt, .zh.vtt → zh
     • .en.vtt, .en-US.vtt, .en-GB.vtt → en
     • .ja.vtt → ja
     • .ko.vtt → ko
   • From content analysis (if filename doesn't indicate language):
     • Count Chinese characters (Unicode range \u4e00-\u9fff)
     • Calculate ratio: Chinese chars / Total chars
     • If ratio > 0.3 → zh
     • Otherwise → en

2. Store the detected language code: video_language (e.g., zh, en)

3. Save the transcript to: <Video Title>.txt

4. Report completion with language info:

   • File path
   • Language code: [zh/en/ja/ko]
   • Language name (e.g., Chinese, English)
   • Total number of lines
   • File size

Error Handling

• No subtitles available: Inform user and suggest alternative (manual transcription or audio extraction)
• Authentication required: Guide user to set up cookies or login
• Network error: Suggest retry or check URL validity
• Unsupported platform: List supported platforms and suggest alternatives

Output Format

File saved: <Video Title>.txt
Language code: zh
Language: Chinese (auto-generated)
Lines: 245
Size: 12.5 KB

The language code (zh, en, etc.) will be used by the yux-video-summary skill for multi-language output generation.