# Kling 4.0 Reference to Video API

> Ģenerē 3–30 sekunžu videoklipus, saglabājot līdz 10 atsauces attēlu, 5 atsauces videoklipu un 7 elementu vizuālo izskatu

Izveido videoklipu no teksta `prompt`, kā arī atsauces attēliem, atsauces videoklipiem un rakstzīmju vai objektu elementiem, uz kuriem uzvednē atsaucas kā @Image1, @Video1 vai @Element1. Ilgums ir no 3 līdz 30 sekundēm (noklusējums: 5), izvades izšķirtspēja ir 720p vai 1080p, bet malu attiecība var būt auto, 16:9, 9:16, 1:1 vai 21:9. Izmantojiet `multi_prompt` atsevišķām uzņemšanas ainām paredzētām uzvednēm; šādā gadījumā kopējais ilgums ir ainu ilgumu summa. Ierobežojumi: 10 attēli, 5 videoklipi pa 3–30 s katrs un 7 elementi, no kuriem līdz 3 var ietvert balsi.

- 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/lv/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 | Ģenerēšanas norādījumi, kas izpilda prasību norādīt `prompt` vai `multi_prompt`. Lai atsauktos uz ievadēm, izmantojiet @Image1, @Video1, @Element1 utt. |
| `multi_prompt` |  | array of object {prompt, duration} \| null | no |  | ≥ 1 items | Ģenerēšanas norādījumi pa kadrējumiem; katra uzvedne definē vienu kadrējumu, kura ilgums veido video kopējo ilgumu. |
| `multi_prompt[].prompt` |  | string | yes |  | 1 – 512 characters | Teksta norādījumi pašreizējam kadrējumam. |
| `multi_prompt[].duration` |  | integer | no | `5` | 1 – 30 | Atsevišķa kadrējuma ilgums sekundēs. |
| `duration` |  | integer | no | `5` | 3 – 30 | Video ilgums sekundēs no 3 līdz 30. |
| `start_image_url` | `image` | string (image URL) \| null | no |  |  | Neobligāts pirmā kadra attēls, kas tiek ieskaitīts attēlu atsauču limitā. Maksimālais faila lielums ir 30.0 MB; platumam un augstumam jābūt vismaz 300 px, bet malu attiecībai — no 0.40 līdz 2.50. |
| `image_urls` | `images` | array of image URL \| null | no |  | ≤ 10 items | Attēlu atsauces, uz kurām atsaucas ar @Image1, @Image2 utt.; ne vairāk kā 10 attēli. Katra faila lielums nedrīkst pārsniegt 30.0 MB, abiem izmēriem jābūt vismaz 300 px, bet malu attiecībai — no 0.40 līdz 2.50. |
| `video_urls` | `videos` | array of video URL \| null | no |  | ≤ 5 items | Līdz 5 atsauces video, uz kuriem atsaucas ar @Video1, @Video2 utt.; katra ilgums ir 3–30 sekundes (ne vairāk kā 30.05 sekundes), un to kopējais ilgums kopā ar elementu video nedrīkst pārsniegt 30 sekundes. Katra faila lielums nedrīkst pārsniegt 300 MB, platumam un augstumam jābūt no 700 px līdz 4553 px. Malu attiecībai jābūt no 0.40 līdz 2.50, bet kadru nomaiņas ātrumam — no 23.9 līdz 60.05 FPS. |
| `elements` |  | array of object {frontal_image_url, reference_image_urls, video_url, voice_id} \| null | no |  | ≤ 7 items | Līdz 7 tēlu vai objektu kolekcija, no kuriem ne vairāk kā 3 var ietvert `voice_id` un ne vairāk kā 3 var izmantot video. Atsaucieties uz šiem elementiem ar @Element1, @Element2 utt. |
| `elements[].frontal_image_url` |  | string (image URL) \| null | no |  |  | Priekšskata attēls, kas rāda elementa galveno skatu. Maksimālais faila lielums ir 30.0 MB; abiem izmēriem jābūt vismaz 300 px, bet malu attiecībai — no 0.40 līdz 2.50. |
| `elements[].reference_image_urls` |  | array of image URL \| null | no |  | ≤ 3 items | Papildu attēli dažādu elementa leņķu rādīšanai, ar 1–3 skatiem. Katra faila lielums nedrīkst pārsniegt 30.0 MB, abiem izmēriem jābūt vismaz 300 px, bet malu attiecībai — no 0.40 līdz 2.50. |
| `elements[].video_url` |  | string (video URL) \| null | no |  |  | Elementa video attēlojums attēlu vietā, kas ilgst 3–30 sekundes (ne vairāk kā 30.05 sekundes). Faila lielums nedrīkst pārsniegt 300 MB; platumam un augstumam jābūt no 700 līdz 4553 px. Atbalstītās malu attiecības ir 0.40–2.50, bet kadru nomaiņas ātrums — 23.9–60.05 FPS. |
| `elements[].voice_id` |  | string \| null | no |  |  | Elementam piešķirtā balss. |
| `resolution` |  | enum (string) | no | `1080p` | `720p`, `1080p` | Izvades izšķirtspēja. |
| `aspect_ratio` |  | enum (string) | no | `16:9` | `auto`, `16:9`, `9:16`, `1:1`, `21:9` | Video proporcijas, kas atlasītas tieši vai iegūtas no atsaucēm, izvēloties '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} | Modeļa izveidotais video. |

## 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