# Kling 4.0 Reference to Video API

> Genereert video's van 3-30 seconden die het uiterlijk van maximaal 10 referentieafbeeldingen, 5 referentievideo's en 7 elementen behouden

Maakt video van een tekstuele `prompt` plus referentieafbeeldingen, referentievideo's en elementen van personages of objecten, waarnaar in de prompt wordt verwezen als @Image1, @Video1 of @Element1. De duur varieert van 3 tot 30 seconden (standaard 5), met uitvoer in 720p of 1080p en beeldverhoudingen auto, 16:9, 9:16, 1:1 of 21:9. Gebruik `multi_prompt` voor prompts per shot; in dat geval is de totale lengte de som van de shotduren. Limieten zijn 10 afbeeldingen, 5 video's van elk 3-30s en 7 elementen, waarvan maximaal 3 een stem kunnen bevatten.

- 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/nl/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 | Generatie-instructies die voldoen aan de vereiste om `prompt` of `multi_prompt` aan te leveren. Gebruik @Image1, @Video1, @Element1 enzovoort om naar aangeleverde invoer te verwijzen. |
| `multi_prompt` |  | array of object {prompt, duration} \| null | no |  | ≥ 1 items | Generatie-instructies per shot, waarbij elke prompt één shot definieert en de duur ervan bijdraagt aan de totale videolengte. |
| `multi_prompt[].prompt` |  | string | yes |  | 1 – 512 characters | Tekstinstructies voor het huidige shot. |
| `multi_prompt[].duration` |  | integer | no | `5` | 1 – 30 | Duur van een afzonderlijk shot, gemeten in seconden. |
| `duration` |  | integer | no | `5` | 3 – 30 | Videolengte in seconden, van 3 tot 30. |
| `start_image_url` | `image` | string (image URL) \| null | no |  |  | Optionele afbeelding voor het eerste frame die meetelt voor de limiet van referentieafbeeldingen. De maximale bestandsgrootte is 30.0 MB; breedte en hoogte moeten elk 300 px bereiken, met een beeldverhouding tussen 0.40 en 2.50. |
| `image_urls` | `images` | array of image URL \| null | no |  | ≤ 10 items | Afbeeldingsreferenties die worden aangeduid met @Image1, @Image2 enzovoort, met maximaal 10 afbeeldingen. Elk bestand is beperkt tot 30.0 MB, vereist minimaal 300 px in beide afmetingen en moet een beeldverhouding tussen 0.40 en 2.50 hebben. |
| `video_urls` | `videos` | array of video URL \| null | no |  | ≤ 5 items | Maximaal 5 referentievideo's, aangeduid met @Video1, @Video2 enzovoort; elke video duurt 3–30 seconden (maximaal 30.05 seconden) en de totale duur samen met elementvideo's mag niet meer dan 30 seconden bedragen. Elk bestand mag maximaal 300 MB groot zijn, met breedte en hoogte elk tussen 700 px en 4553 px. De beeldverhouding moet tussen 0.40 en 2.50 liggen en de framesnelheid tussen 23.9 en 60.05 FPS. |
| `elements` |  | array of object {frontal_image_url, reference_image_urls, video_url, voice_id} \| null | no |  | ≤ 7 items | Verzameling van maximaal 7 personages of objecten, waarvan maximaal 3 een `voice_id` mogen bevatten en maximaal 3 video mogen gebruiken. Duid deze elementen aan als @Element1, @Element2 enzovoort. |
| `elements[].frontal_image_url` |  | string (image URL) \| null | no |  |  | Frontale afbeelding die het hoofdbeeld van het element toont. De maximale bestandsgrootte is 30.0 MB; beide afmetingen moeten minimaal 300 px zijn en de beeldverhouding moet tussen 0.40 en 2.50 liggen. |
| `elements[].reference_image_urls` |  | array of image URL \| null | no |  | ≤ 3 items | Aanvullende afbeeldingen vanuit verschillende hoeken van het element, met 1 tot 3 weergaven. Elk bestand mag maximaal 30.0 MB groot zijn, moet minimaal 300 px in beide afmetingen meten en moet een beeldverhouding tussen 0.40 en 2.50 hebben. |
| `elements[].video_url` |  | string (video URL) \| null | no |  |  | Videoweergave van een element in plaats van afbeeldingen, met een duur van 3–30 seconden (maximaal 30.05 seconden). Het bestand mag niet groter zijn dan 300 MB; breedte en hoogte moeten elk tussen 700–4553 px liggen. Ondersteunde beeldverhoudingen lopen van 0.40–2.50, met framesnelheden van 23.9–60.05 FPS. |
| `elements[].voice_id` |  | string \| null | no |  |  | Stem die aan het element is toegewezen. |
| `resolution` |  | enum (string) | no | `1080p` | `720p`, `1080p` | Resolutie van de uitvoer. |
| `aspect_ratio` |  | enum (string) | no | `16:9` | `auto`, `16:9`, `9:16`, `1:1`, `21:9` | Videoproporties, expliciet geselecteerd of afgeleid van de referenties door 'auto' te kiezen. |

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} | Video die door het model is geproduceerd. |

## 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