> ## Documentation Index
> Fetch the complete documentation index at: https://agenthook.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# 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`](/tools/make-video) — 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

```bash theme={null}
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](/credits-and-refunds#instant-refunds-on-failure).

## Pricing

Captioning is a flat **15 credits** per video, regardless of length or style — see [Credits & refunds](/credits-and-refunds#what-runs-cost).