# Kling 4.0 Reference to Video API

> Bumubuo ng 3-30 segundong video na pinananatili ang hitsura ng hanggang 10 reference larawan, 5 reference video at 7 element

Gumagawa ng video mula sa teksto na `prompt` kasama ang reference na mga larawan, video at element ng character o object, na tinutukoy sa prompt bilang @Image1, @Video1 o @Element1. Ang duration ay 3 hanggang 30 segundo (default na 5), na may output na 720p o 1080p at aspect ratio na auto, 16:9, 9:16, 1:1 o 21:9. Gamitin ang `multi_prompt` para sa prompt bawat shot; sa ganitong kaso, ang kabuuang haba ay kabuuan ng mga duration ng shot. Mga limitasyon: 10 larawan, 5 video na tig-3-30s, at 7 element, na hanggang 3 dito ay maaaring may voice.

- Model id: `kling/v4/reference-to-video`
- Made by: Kling
- Category: Reference to Video
- Output: video
- Price per second of your output video: from $0.157 / second of output video (cheapest run $0.157 (157 API credits))
- Run: `POST https://api.doitong.com/v1/run/kling/v4/reference-to-video`
- Quote: `POST https://api.doitong.com/v1/quote/kling/v4/reference-to-video`
- Docs page: https://doitong.com/fil/developers/models/kling/v4/reference-to-video

## Pricing

Price: **from $0.157 / second of output video** (the lowest tier; the quote prices your exact input). Price per second of your output video: the input files are measured before the run (length, resolution, frame rate). The quote measures the same files and is exactly what the run charges.

Price by tier:

- 720p: $0.157 / second of output video
- 1080p: $0.235 / second of output video

The full example input below costs $1.175 = 1175 API credits (5 s output video × $0.235 (1080p)).

Prices are the upstream price in USD, paid from the API balance in API credits (1000 API credits = 1 USD). `POST https://api.doitong.com/v1/quote/kling/v4/reference-to-video` with the same JSON body returns the exact price for that input; the quote is exactly what a run charges. Invalid input is never charged and failed or canceled requests are refunded automatically.

## Input parameters

Send either the canonical name or the native field name (not both). Canonical names are the same across models.

| Parameter | Canonical name | Type | Required | Default | Allowed values / range | Description |
|---|---|---|---|---|---|---|
| `prompt` |  | string \| null | no |  | ≤ 2500 characters | Mga instruction sa pagbuo na tumutupad sa requirement na magbigay ng alinman sa `prompt` o `multi_prompt`. Para tukuyin ang mga ibinigay na input, gamitin ang @Image1, @Video1, @Element1, at iba pa. |
| `multi_prompt` |  | array of object {prompt, duration} \| null | no |  | ≥ 1 items | Mga instruction sa pagbuo bawat shot, kung saan tinutukoy ng bawat prompt ang isang shot na ang tagal ay idinadagdag sa kabuuang haba ng video. |
| `multi_prompt[].prompt` |  | string | yes |  | 1 – 512 characters | Mga text instruction para sa kasalukuyang shot. |
| `multi_prompt[].duration` |  | integer | no | `5` | 1 – 30 | Tagal ng isang shot, sinusukat sa segundo. |
| `duration` |  | integer | no | `5` | 3 – 30 | Haba ng video sa segundo, mula 3 hanggang 30. |
| `start_image_url` | `image` | string (image URL) \| null | no |  |  | Opsyonal na larawan ng first frame na ibinibilang sa limitasyon ng larawan reference. Maximum na laki ng file ay 30.0 MB; dapat hindi bababa sa 300 px ang lapad at taas, at nasa pagitan ng 0.40 at 2.50 ang aspect ratio. |
| `image_urls` | `images` | array of image URL \| null | no |  | ≤ 10 items | Mga reference ng larawan na tinutukoy gamit ang @Image1, @Image2, at iba pa, na may maximum na 10 larawan. Limitado sa 30.0 MB ang bawat file, nangangailangan ng hindi bababa sa 300 px sa parehong dimension, at dapat may aspect ratio na 0.40 hanggang 2.50. |
| `video_urls` | `videos` | array of video URL \| null | no |  | ≤ 5 items | Hanggang 5 reference video, na tinutukoy gamit ang @Video1, @Video2, at iba pa; bawat isa ay may tagal na 3–30 segundo (30.05 segundo maximum), at ang pinagsamang tagal nila at ng mga element video ay hindi maaaring lumampas sa 30 segundo. Hindi dapat lumampas sa 300 MB ang bawat file, na may lapad at taas na 700 px hanggang 4553 px. Dapat nasa pagitan ng 0.40 at 2.50 ang aspect ratio, at 23.9 hanggang 60.05 FPS ang frame rate. |
| `elements` |  | array of object {frontal_image_url, reference_image_urls, video_url, voice_id} \| null | no |  | ≤ 7 items | Collection ng hanggang 7 character o object, kung saan hanggang 3 lamang ang maaaring may `voice_id` at hanggang 3 ang maaaring gumamit ng video. Tukuyin ang mga element na ito bilang @Element1, @Element2, at iba pa. |
| `elements[].frontal_image_url` |  | string (image URL) \| null | no |  |  | Frontal na larawang nagpapakita ng pangunahing view ng element. Maximum na laki ng file ay 30.0 MB; dapat hindi bababa sa 300 px ang parehong dimension, at nasa pagitan ng 0.40 at 2.50 ang aspect ratio. |
| `elements[].reference_image_urls` |  | array of image URL \| null | no |  | ≤ 3 items | Mga supplementary na larawan na nagpapakita ng iba't ibang anggulo ng element, na may 1 hanggang 3 view. Hanggang 30.0 MB lamang ang bawat file, dapat hindi bababa sa 300 px ang parehong dimension, at dapat may aspect ratio na 0.40 hanggang 2.50. |
| `elements[].video_url` |  | string (video URL) \| null | no |  |  | Video representation ng isang element sa halip na mga larawan, na may tagal na 3–30 segundo (30.05 segundo maximum). Hindi dapat lumampas sa 300 MB ang file; dapat nasa loob ng 700–4553 px ang lapad at taas. Sinusuportahan ang aspect ratio na 0.40–2.50, na may frame rate na 23.9–60.05 FPS. |
| `elements[].voice_id` |  | string \| null | no |  |  | Voice na itinalaga sa element. |
| `resolution` |  | enum (string) | no | `1080p` | `720p`, `1080p` | Resolution ng output. |
| `aspect_ratio` |  | enum (string) | no | `16:9` | `auto`, `16:9`, `9:16`, `1:1`, `21:9` | Mga proporsyon ng video, tahasang pinipili o hinango mula sa mga reference sa pamamagitan ng pagpili sa 'auto'. |

File parameters (`image`, `images`, `videos`) take a public `https://` URL, a `data:` URI up to 10 MB, or the `file_url` of an upload from `POST /files`.

## Example input

Required parameters only:

```json
{}
```

A fuller example:

```json
{
  "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field"
}
```

## Run it

Set `DOITONG_API_KEY` to a key from https://doitong.com/developers/dashboard#keys. `?wait=20` returns the finished request in the same call when it is ready within 20 seconds; otherwise poll `GET /requests/{id}` (it also accepts `?wait=`), or pass `webhook_url`.

### curl

```bash
# Run the model; wait up to 20 s for the finished result in the same call
curl -X POST "https://api.doitong.com/v1/run/kling/v4/reference-to-video?wait=20" \
  -H "Authorization: Bearer $DOITONG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field"
  }'

# Still "queued" or "running"? Poll with the id from the response:
curl "https://api.doitong.com/v1/requests/REQUEST_ID?wait=20" \
  -H "Authorization: Bearer $DOITONG_API_KEY"
```

### JavaScript

```javascript
const API = "https://api.doitong.com/v1";
const headers = {
  "Authorization": "Bearer " + process.env.DOITONG_API_KEY,
  "Content-Type": "application/json",
};

// Run the model; wait up to 20 s for the finished result in the same call
let res = await fetch(API + "/run/kling/v4/reference-to-video?wait=20", {
  method: "POST",
  headers,
  body: JSON.stringify({
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field"
  }),
});
let request = await res.json();
if (!res.ok) throw new Error(request.error.code + ": " + request.error.message);

// Not finished yet: long-poll until it is
while (request.status === "queued" || request.status === "running") {
  res = await fetch(API + "/requests/" + request.id + "?wait=20", { headers });
  request = await res.json();
}
if (request.status !== "succeeded") throw new Error(JSON.stringify(request.error));
console.log(request.outputs.map((o) => o.url), request.cost.credits + " API credits ($" + request.cost.usd + ")");
```

### Python

```python
import os
import requests

API = "https://api.doitong.com/v1"
headers = {"Authorization": "Bearer " + os.environ["DOITONG_API_KEY"]}

payload = {
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
}

# Run the model; wait up to 20 s for the finished result in the same call
r = requests.post(API + "/run/kling/v4/reference-to-video", params={"wait": 20}, json=payload, headers=headers)
request = r.json()
if not r.ok:
    raise RuntimeError(request["error"]["code"] + ": " + request["error"]["message"])

# Not finished yet: long-poll until it is
while request["status"] in ("queued", "running"):
    request = requests.get(API + "/requests/" + request["id"], params={"wait": 20}, headers=headers).json()
if request["status"] != "succeeded":
    raise RuntimeError(request["error"])
print([o["url"] for o in request["outputs"]], request["cost"]["credits"], "API credits", "$" + request["cost"]["usd"])
```

### MCP

The MCP server at `https://api.doitong.com/v1/mcp` exposes the tools `search_models`, `get_model`, `quote`, `run`, `get_request`, `cancel_request`, `list_requests`, `create_upload` and `get_account`. A `run` call for this model:

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "run",
    "arguments": {
      "model_id": "kling/v4/reference-to-video",
      "input": {
        "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field"
      },
      "wait_seconds": 20
    }
  }
}
```

## Response

Every call returns a request object. `status` is one of `queued`, `running`, `succeeded`, `failed`, `canceled`. `outputs` lists the generated files with URLs on our storage (kept forever, or 7 days with `?storage=temporary`; `storage` says which); `output` is the model's own result object with the same URLs.

```json
{
  "id": "req_8k2m4q7x1z9c3v5b6n0p2r4t",
  "object": "request",
  "model": "kling/v4/reference-to-video",
  "status": "succeeded",
  "created_at": "2026-10-20T12:00:00Z",
  "started_at": "2026-10-20T12:00:02Z",
  "completed_at": "2026-10-20T12:00:09Z",
  "queue_position": null,
  "cost": {
    "credits": 1175,
    "usd": "1.175",
    "charged": 1175,
    "refunded": 0
  },
  "input": {
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field"
  },
  "output": {
    "video": {
      "url": "https://content.doitong.com/dev-api/2026/10/20/req_8k2m4q7x1z9c3v5b6n0p2r4t/0-output.mp4",
      "content_type": "video/mp4",
      "file_name": "0-output.mp4",
      "file_size": 1843200
    }
  },
  "outputs": [
    {
      "type": "video",
      "url": "https://content.doitong.com/dev-api/2026/10/20/req_8k2m4q7x1z9c3v5b6n0p2r4t/0-output.mp4",
      "content_type": "video/mp4",
      "file_size": 1843200,
      "width": 1280,
      "height": 720,
      "duration": 5,
      "stored": true
    }
  ],
  "error": null,
  "metrics": {
    "inference_seconds": 6.8
  },
  "urls": {
    "self": "https://api.doitong.com/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t",
    "cancel": "https://api.doitong.com/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t/cancel"
  }
}
```

### Output fields (`output`)

| Field | Type | Description |
|---|---|---|
| `video` | object {url, content_type, file_name, file_size} | Videong ginawa ng modelo. |

## Related models

- [Kling 4.0 Text to Video](https://doitong.com/developers/models/kling/v4/text-to-video.md) (`kling/v4/text-to-video`): from $0.157 / second of output video
- [Seedance 2.0 Fast Reference to Video](https://doitong.com/developers/models/bytedance/seedance-2.0/fast/reference-to-video.md) (`bytedance/seedance-2.0/fast/reference-to-video`): from $0.113 / second
- [Seedance 2.0 Reference to Video](https://doitong.com/developers/models/bytedance/seedance-2.0/reference-to-video.md) (`bytedance/seedance-2.0/reference-to-video`): from $0.141 / second
- [Wan 3.0 Reference to Video](https://doitong.com/developers/models/alibaba/wan-3.0/reference-to-video.md) (`alibaba/wan-3.0/reference-to-video`): from $0.05 / second
- [Kling O1 Reference Image to Video \[Pro\]](https://doitong.com/developers/models/kling-video/o1/reference-to-video.md) (`kling-video/o1/reference-to-video`): $0.112 / second
- [Kling O1 Reference Image to Video \[Standard\]](https://doitong.com/developers/models/kling-video/o1/standard/reference-to-video.md) (`kling-video/o1/standard/reference-to-video`): $0.084 / second
- [Kling O3 Reference to Video \[Pro\]](https://doitong.com/developers/models/kling-video/o3/pro/reference-to-video.md) (`kling-video/o3/pro/reference-to-video`): from $0.112 / second
- [Kling O3 Reference to Video \[Standard\]](https://doitong.com/developers/models/kling-video/o3/standard/reference-to-video.md) (`kling-video/o3/standard/reference-to-video`): from $0.084 / second

## Links

- HTML page: https://doitong.com/developers/models/kling/v4/reference-to-video
- All models and guides for AI agents: https://doitong.com/developers/llms.txt
- OpenAPI 3.1 with this model's typed request body: https://doitong.com/developers/openapi.json?model=kling/v4/reference-to-video
- Errors: https://doitong.com/developers/docs/errors
- Model details as JSON: https://api.doitong.com/v1/models/kling/v4/reference-to-video