# Kling O3 Reference to Video [Pro] API

> Pro reference-to-video that keeps characters and objects consistent using images and elements

Builds video scenes from reference `image_urls` cited as @Image1 and so on, plus `elements` for characters or objects. Optional `start_image_url` and `end_image_url` fix the first and last frames. Duration is 3 to 15 seconds, aspect ratio 16:9, 9:16 or 1:1. Supports `multi_prompt` shots and optional audio.

- Model id: `kling-video/o3/pro/reference-to-video`
- Made by: Kling
- Category: Reference to Video
- Output: video
- Price: from $0.112 / second (5 s ≈ $0.56) (cheapest run $0.56 (560 API credits))
- Run: `POST https://api.doitong.com/v1/run/kling-video/o3/pro/reference-to-video`
- Quote: `POST https://api.doitong.com/v1/quote/kling-video/o3/pro/reference-to-video`
- Docs page: https://doitong.com/developers/models/kling-video/o3/pro/reference-to-video

## Pricing

Price: **from $0.112 / second (5 s ≈ $0.56)** (the lowest tier; the quote prices your exact input). Billed per second of output (`duration`, default 15).

Price rules (the first rule that matches the input wins; a parameter you leave out counts as its default):

- When `generate_audio` = true: $0.14 (140 API credits) / second

The full example input below costs $0.56 = 560 API credits (5 s × 112 API credits).

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-video/o3/pro/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 |
|---|---|---|---|---|---|---|
| `enable_safety_checker` |  | boolean | no | `true` |  | Safety checks can be disabled only with account authorization; requests without authorization always undergo checking. |
| `prompt` |  | string \| null | no |  | ≤ 2500 characters | Text instructions used to generate the video. Supply exactly one of prompt or multi_prompt. |
| `multi_prompt` |  | array of object {prompt, duration} \| null | no |  |  | Prompt list used to generate a video with multiple shots. |
| `multi_prompt[].prompt` |  | string | yes |  |  | Text instructions for the current shot. |
| `multi_prompt[].duration` |  | enum (string) | no | `5` | `1`, `2`, `3`, `4`, `5`, `6`, `7`, `8`, `9`, `10`, `11`, `12`, `13`, `14`, `15` | Length of the current shot, measured in seconds. |
| `start_image_url` | `image` | string (image URL) \| null | no |  |  | Image used for the video's opening frame. File size must not exceed 50 MB; width and height must each be at least 300px, with an aspect ratio between 0.40 and 2.50. |
| `end_image_url` | `end_image` | string (image URL) \| null | no |  |  | Image that supplies the video's final frame, limited to 50 MB. Width and height must each be at least 300 px, with an aspect ratio from 0.40 to 2.50. |
| `image_urls` | `images` | array of image URL \| null | no |  |  | Images that guide style or appearance, addressed in the prompt using @Image1, @Image2, and so on. With video input, elements and reference images together cannot exceed 4 entries. Each file is limited to 50 MB, with width and height each at least 300 px and an aspect ratio from 0.40 to 2.50. |
| `elements` |  | array of object {frontal_image_url, reference_image_urls, video_url, voice_id} \| null | no |  |  | Characters or objects to include, addressed in the prompt using @Element1 and @Element2. |
| `elements[].frontal_image_url` |  | string (image URL) \| null | no |  |  | Front-facing image showing the element's main view. File size must not exceed 50 MB; width and height must each be at least 300px, with an aspect ratio between 0.40 and 2.50. |
| `elements[].reference_image_urls` |  | array of image URL \| null | no |  |  | Supply 1–3 additional reference images showing different angles. Each image must have an aspect ratio between 0.40 and 2.50, measure at least 300px in both dimensions, and be no larger than 50.0MB. |
| `elements[].video_url` |  | string (video URL) \| null | no |  |  | URL pointing to an element's video; only one element per request may include a video. The file must be at most 200 MB, with width and height each between 720px and 2160px. Duration must fall between 3 seconds and 10.05 seconds, and FPS between 24.0 and 60.0. |
| `elements[].voice_id` |  | string \| null | no |  |  | Voice ID assigned to the element. References to that element use its assigned voice. |
| `generate_audio` |  | boolean | no | `false` |  | Controls whether native audio is generated alongside the video. |
| `duration` |  | enum (string) | no | `5` | `3`, `4`, `5`, `6`, `7`, `8`, `9`, `10`, `11`, `12`, `13`, `14`, `15` | Video length, ranging from 3 to 15 seconds. |
| `shot_type` |  | enum (string) | no | `customize` | `customize`, `intelligent` | Choose how multi-shot generation plans its shots; selecting 'intelligent' delegates the shot structure to the model. |
| `aspect_ratio` |  | enum (string) | no | `16:9` | `16:9`, `9:16`, `1:1` | Width-to-height ratio for frames in the generated video. |

File parameters (`image`, `end_image`, `images`) 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-video/o3/pro/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-video/o3/pro/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-video/o3/pro/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-video/o3/pro/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-video/o3/pro/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": 560,
    "usd": "0.56",
    "charged": 560,
    "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 produced by the model. |

## Related models

- [Kling O3 Text to Video \[Pro\]](https://doitong.com/developers/models/kling-video/o3/pro/text-to-video.md) (`kling-video/o3/pro/text-to-video`): from $0.112 / second
- [Kling O3 Text to Video \[Standard\]](https://doitong.com/developers/models/kling-video/o3/standard/text-to-video.md) (`kling-video/o3/standard/text-to-video`): from $0.084 / second
- [Kling Video · O3 · 4k · Text to Video](https://doitong.com/developers/models/kling-video/o3/4k/text-to-video.md) (`kling-video/o3/4k/text-to-video`): $0.42 / second
- [Kling O3 Image to Video · Pro](https://doitong.com/developers/models/kling-video/o3/pro/image-to-video.md) (`kling-video/o3/pro/image-to-video`): from $0.112 / second
- [Kling O3 Image to Video · Standard](https://doitong.com/developers/models/kling-video/o3/standard/image-to-video.md) (`kling-video/o3/standard/image-to-video`): from $0.084 / second
- [Kling Video · O3 · 4k · Image to Video](https://doitong.com/developers/models/kling-video/o3/4k/image-to-video.md) (`kling-video/o3/4k/image-to-video`): $0.42 / 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
- [Kling Video · O3 · 4k · Reference to Video](https://doitong.com/developers/models/kling-video/o3/4k/reference-to-video.md) (`kling-video/o3/4k/reference-to-video`): $0.42 / second

## Links

- HTML page: https://doitong.com/developers/models/kling-video/o3/pro/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-video/o3/pro/reference-to-video
- Errors: https://doitong.com/developers/docs/errors
- Model details as JSON: https://api.doitong.com/v1/models/kling-video/o3/pro/reference-to-video