Extract Subtitles

Extract Subtitles

Pull embedded subtitle tracks out of a container (MKV/MP4/etc.) and save them as .srt and .vtt files — one per track, named by language.

When to use

Use this skill when a user wants caption/subtitle files extracted from a video that already contains subtitle streams, or wants to list which subtitle tracks a file has.

Workflow

1. Confirm ffmpeg/ffprobe are available.
2. List subtitle streams first so the user sees what's available:

   ffprobe -v error -select_streams s -show_entries stream=index,codec_name:stream_tags=language -of json INPUT
   

3. Run the bundled script to extract every text-based track to SRT + VTT:

   "${CLAUDE_PLUGIN_ROOT}/skills/extract-subtitles/scripts/extract-subs.sh" INPUT out_prefix
   

4. Report the files written (with languages). If a track is image-based (PICTURE codecs like hdmv_pgs_subtitle / dvd_subtitle), note that it can't be converted to text without OCR.

Key details

• Text subtitle codecs (subrip, mov_text, ass, webvtt) convert cleanly to SRT/VTT.
• Image-based subtitles (PGS/VOBSUB) are bitmaps — extraction to text requires OCR, which is out of scope; surface this clearly rather than producing empty files.
• No embedded track? The source has no subtitles to extract — transcription (speech-to- text) is a different task; say so instead of failing silently.

Resources

• scripts/extract-subs.sh — lists subtitle streams and extracts text tracks to SRT/VTT.