caption_video

Burn styled subtitles into an existing video.

POST /api/v1/tools/caption_video/run

Takes a video URL, transcribes the speech with word-level timestamps, and returns the same video with styled subtitles burned in. Two presets: movie (clean cinematic lower-thirds) and tiktok (bold word-by-word social style).

Works on any video you have a URL for — including videos generated here. (If you’re generating the video in the same breath, prefer make_video with captions: true — it chains both steps in one run.)

Arguments

Argument	Type	Required	Default	Description
video_url	string (URL)	yes	—	Publicly fetchable URL of the video to caption.
style	string	no	"movie"	One of movie, tiktok.
language	string	no	"auto"	Spoken-language hint for transcription. Default auto-detects.

Example

curl -X POST https://getagenthook.com/api/v1/tools/caption_video/run \
  -H "Authorization: Bearer $AGENTHOOK_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "video_url": "https://media.agenthook.com/users/u_1/runs/run_abc123/0.mp4",
    "style": "tiktok"
  }'

Response

202 with run_id; poll GET /api/v1/runs/{run_id}. On completed:

• output[0] — the captioned MP4, on durable storage.
• transcript — the full transcription text, stored on the run and full-text searchable via GET /api/v1/generations?q=....

On failed, the flat caption charge is refunded instantly.

Pricing

Captioning is a flat 15 credits per video, regardless of length or style — see Credits & refunds.