Caption Video

Caption Video

Render a video clip with captions overlaid using the Remotion captioner project.

When to Apply

Use this skill when:

• User provides a video file and asks to add captions or subtitles
• User says "caption this", "add captions", "burn in subtitles", or similar
• User provides both a video file and an SRT file
• User wants to preview multiple caption styles on a video
• User has a video + SRT pair and wants styled caption output

Do NOT use this skill for:

• Transcribing audio to text (use voice-memo-transcriber instead)
• Splitting video into clips (use video-clipper instead)
• Uploading video (use wistia-uploader instead)

Inputs

1. Video file path (required) — path to .mp4 or other video file
2. SRT file path (optional) — if not provided, look for one with the same basename
3. --variant <name> (optional) — caption animation style. Default: slide-up
4. --end-seconds <n> (optional) — trim render to first N seconds (useful for previews)

Available Variants

fade, slide-up, spring-pop, blur-release, typewriter, underline-sweep

Default is slide-up (HubSpot orange pill, white text, rises 24px while fading in).

Instructions for Claude

Step 1: Resolve Inputs

• If the user gave both a video path and an SRT path, use them.
• If only a video path is given, look for an SRT with the same basename in the same folder (e.g. clip.mp4 -> clip.srt). If not found, ask the user for the SRT path.
• If the user gave a folder path, look inside it for exactly one .mp4 + one .srt pair and use them. If multiple pairs exist, list them and ask which.

Step 2: Run the Render

cd /Users/jvincent/Projects/remotion-captioner && node render.mjs "<video>" "<srt>" [--variant <name>] [--end-seconds <n>]

Use run_in_background: true — renders for a ~3min clip take ~1-2 minutes.

Only change the variant from slide-up if the user explicitly passes --variant <name>.

Step 3: Report

When done, print the output file path and file size. Don't re-explain the styling unless asked.

Output Naming

• Default style: <video-basename>.captioned.mp4 alongside the source
• Non-default variant or trimmed: <video-basename>.captioned.<variant>[.<Ns>].mp4

Previewing Multiple Styles

Pass --variant all --end-seconds 25 to render 25-second samples of every style.

Notes

• The remotion-captioner project is at /Users/jvincent/Projects/remotion-captioner/ (outside Knowledge System repo)
• All processing is local — no external services