# Kling 4.0 Reference to Video API

> Genererer videoer på 3–30 sekunder som bevarer utseendet til opptil 10 referansebilder, 5 referansevideoer og 7 elementer

Oppretter video fra en tekstbasert `prompt` samt referansebilder, referansevideoer og karakter- eller objektelementer, som refereres til i prompten som @Image1, @Video1 eller @Element1. Varigheten er fra 3 til 30 sekunder (standard 5), med utdata i 720p eller 1080p og størrelsesforholdene auto, 16:9, 9:16, 1:1 eller 21:9. Bruk `multi_prompt` for prompt per bildeutsnitt; i så fall er den totale lengden summen av varighetene for bildeutsnittene. Grensene er 10 bilder, 5 videoer på 3–30s hver og 7 elementer, hvorav opptil 3 kan ha en stemme.

- 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.ru/v1/run/kling/v4/reference-to-video`
- Quote: `POST https://api.doitong.ru/v1/quote/kling/v4/reference-to-video`
- Docs page: https://doitong.com/no/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.ru/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 | Genereringsinstruksjoner som oppfyller kravet om å oppgi enten `prompt` eller `multi_prompt`. For å referere til oppgitte inndata, bruk @Image1, @Video1, @Element1 og så videre. |
| `multi_prompt` |  | array of object {prompt, duration} \| null | no |  | ≥ 1 items | Genereringsinstruksjoner opptak for opptak, der hver prompt definerer ett opptak hvis varighet bidrar til videoens totale lengde. |
| `multi_prompt[].prompt` |  | string | yes |  | 1 – 512 characters | Tekstinstruksjoner for det gjeldende opptaket. |
| `multi_prompt[].duration` |  | integer | no | `5` | 1 – 30 | Varigheten til et enkelt opptak, målt i sekunder. |
| `duration` |  | integer | no | `5` | 3 – 30 | Videolengde i sekunder, fra 3 til 30. |
| `start_image_url` | `image` | string (image URL) \| null | no |  |  | Valgfritt bilde for første bilde som teller mot grensen for bildereferanser. Maksimal filstørrelse er 30.0 MB; bredde og høyde må hver være minst 300 px, med et sideforhold mellom 0.40 og 2.50. |
| `image_urls` | `images` | array of image URL \| null | no |  | ≤ 10 items | Bildereferanser referert til med @Image1, @Image2 og så videre, med opptil 10 bilder. Hver fil er begrenset til 30.0 MB, krever minst 300 px i begge dimensjoner og må ha et sideforhold mellom 0.40 og 2.50. |
| `video_urls` | `videos` | array of video URL \| null | no |  | ≤ 5 items | Opptil 5 referansevideoer, referert til med @Video1, @Video2 og så videre; hver varer 3–30 sekunder (maksimalt 30.05 sekunder), og den samlede varigheten med elementvideoer kan ikke overstige 30 sekunder. Hver fil må være på høyst 300 MB, med bredde og høyde mellom 700 px og 4553 px. Sideforholdet må være mellom 0.40 og 2.50, og bildefrekvensen mellom 23.9 og 60.05 FPS. |
| `elements` |  | array of object {frontal_image_url, reference_image_urls, video_url, voice_id} \| null | no |  | ≤ 7 items | Samling med opptil 7 figurer eller objekter, hvorav høyst 3 kan inkludere en `voice_id` og høyst 3 kan bruke video. Referer til disse elementene som @Element1, @Element2 og så videre. |
| `elements[].frontal_image_url` |  | string (image URL) \| null | no |  |  | Frontvendt bilde som viser elementets hovedvisning. Maksimal filstørrelse er 30.0 MB; begge dimensjonene må være minst 300 px, og sideforholdet må være mellom 0.40 og 2.50. |
| `elements[].reference_image_urls` |  | array of image URL \| null | no |  | ≤ 3 items | Supplerende bilder som viser ulike vinkler av elementet, med 1 til 3 visninger. Hver fil kan være på høyst 30.0 MB, må være minst 300 px i begge dimensjoner og må ha et sideforhold mellom 0.40 og 2.50. |
| `elements[].video_url` |  | string (video URL) \| null | no |  |  | Videorepresentasjon av et element i stedet for bilder, med varighet på 3–30 sekunder (maksimalt 30.05 sekunder). Filen må ikke overstige 300 MB; både bredde og høyde må være innenfor 700–4553 px. Støttede sideforhold er 0.40–2.50, med bildefrekvenser på 23.9–60.05 FPS. |
| `elements[].voice_id` |  | string \| null | no |  |  | Stemme tildelt elementet. |
| `resolution` |  | enum (string) | no | `1080p` | `720p`, `1080p` | Oppløsning for utdata. |
| `aspect_ratio` |  | enum (string) | no | `16:9` | `auto`, `16:9`, `9:16`, `1:1`, `21:9` | Videoproporsjoner, valgt eksplisitt eller utledet fra referansene ved å velge '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.ru/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.ru/v1/requests/REQUEST_ID?wait=20" \
  -H "Authorization: Bearer $DOITONG_API_KEY"
```

### JavaScript

```javascript
const API = "https://api.doitong.ru/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.ru/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.ru/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.ru/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t",
    "cancel": "https://api.doitong.ru/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t/cancel"
  }
}
```

### Output fields (`output`)

| Field | Type | Description |
|---|---|---|
| `video` | object {url, content_type, file_name, file_size} | Video produsert av modellen. |

## 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.ru/v1/models/kling/v4/reference-to-video