# LTX Video 2.3 Pro · Extend Video API

> Mở rộng video chuyên nghiệp, tiếp tục clip ở cuối hoặc đầu trong 2 đến 20 giây

Kéo dài video có sẵn, theo lời nhắc tùy chọn mô tả phần mới. `duration` là 2 đến 20 giây (mặc định 5). `mode` chọn mở rộng ở cuối hoặc đầu. `context` (1 đến 20 giây) đặt lượng nguồn được dùng làm ngữ cảnh; mặc định sử dụng nhiều nhất có thể trong giới hạn 505 khung hình.

- Model id: `ltx-2.3/extend-video`
- Made by: Lightricks
- Category: Video to Video
- Output: video
- Price: $0.10 / second (5 s ≈ $0.50) (cheapest run $0.50 (500 API credits))
- Run: `POST https://api.doitong.com/v1/run/ltx-2.3/extend-video`
- Quote: `POST https://api.doitong.com/v1/quote/ltx-2.3/extend-video`
- Docs page: https://doitong.com/vi/developers/models/ltx-2.3/extend-video

## Pricing

Price: **$0.10 / second (5 s ≈ $0.50)**. Billed per second of output (`duration`, default 20).

The full example input below costs $0.50 = 500 API credits (5 s × 100 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/ltx-2.3/extend-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 |
|---|---|---|---|---|---|---|
| `video_url` | `video` | string (video URL) | yes |  |  | URL trỏ đến video sẽ được kéo dài. |
| `prompt` |  | string \| null | no |  | ≤ 5000 characters | Mô tả các sự kiện cần tạo trong phần mở rộng của video. |
| `duration` |  | number | no | `5` | 2 – 20 | Độ dài mở rộng video, giới hạn trong khoảng từ 2 giây đến 20 giây. |
| `mode` |  | enum (string) | no | `end` | `start`, `end` | Vị trí mở rộng: 'end' thêm cảnh quay sau video, còn 'start' thêm cảnh quay trước video. |
| `context` |  | number \| null | no |  | 1 – 20 | Độ dài ngữ cảnh video đầu vào dùng để tạo phần mở rộng. Bỏ qua giá trị này sẽ chọn lượng ngữ cảnh khả dụng tối đa trong giới hạn 505 khung hình; thời lượng rõ ràng phải nằm trong khoảng từ 1 giây đến 20 giây. |
| `enable_safety_checker` |  | boolean | no | `true` |  | Có thể nới lỏng việc kiểm duyệt bằng cách đặt thành false, nếu người gọi được cấp quyền. |

File parameters (`video`) 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
{
  "video": "https://content.doitong.com/video/showcase/v3/gen_fox_cartoon.mp4"
}
```

A fuller example:

```json
{
  "video_url": "https://content.doitong.com/video/showcase/v3/gen_fox_cartoon.mp4"
}
```

## 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/ltx-2.3/extend-video?wait=20" \
  -H "Authorization: Bearer $DOITONG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "video_url": "https://content.doitong.com/video/showcase/v3/gen_fox_cartoon.mp4"
  }'

# 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/ltx-2.3/extend-video?wait=20", {
  method: "POST",
  headers,
  body: JSON.stringify({
    "video_url": "https://content.doitong.com/video/showcase/v3/gen_fox_cartoon.mp4"
  }),
});
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 = {
    "video_url": "https://content.doitong.com/video/showcase/v3/gen_fox_cartoon.mp4",
}

# Run the model; wait up to 20 s for the finished result in the same call
r = requests.post(API + "/run/ltx-2.3/extend-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": "ltx-2.3/extend-video",
      "input": {
        "video_url": "https://content.doitong.com/video/showcase/v3/gen_fox_cartoon.mp4"
      },
      "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": "ltx-2.3/extend-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": 500,
    "usd": "0.50",
    "charged": 500,
    "refunded": 0
  },
  "input": {
    "video_url": "https://content.doitong.com/video/showcase/v3/gen_fox_cartoon.mp4"
  },
  "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,
      "width": 1024,
      "height": 768,
      "fps": 1.0,
      "duration": 5,
      "num_frames": 1
    }
  },
  "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, width, height, fps, duration, num_frames} | Tệp video chứa kết quả mở rộng. |

## Related models

- [LTX 2.3 Video Fast · Text to Video](https://doitong.com/developers/models/ltx-2.3/text-to-video/fast.md) (`ltx-2.3/text-to-video/fast`): from $0.06 / second
- [LTX Video 2.3 Pro · Text to Video](https://doitong.com/developers/models/ltx-2.3/text-to-video.md) (`ltx-2.3/text-to-video`): from $0.08 / second
- [LTX 2.3 Video Fast · Image to Video](https://doitong.com/developers/models/ltx-2.3/image-to-video/fast.md) (`ltx-2.3/image-to-video/fast`): from $0.06 / second
- [LTX 2.3 Video Pro · Image to Video](https://doitong.com/developers/models/ltx-2.3/image-to-video.md) (`ltx-2.3/image-to-video`): from $0.08 / second
- [Ltx 2.3](https://doitong.com/developers/models/ltx-2.3/reframe.md) (`ltx-2.3/reframe`): from $0.10 / second of input video
- [LTX Video 2.3 Pro · Retake Video](https://doitong.com/developers/models/ltx-2.3/retake-video.md) (`ltx-2.3/retake-video`): $0.10 / second
- [LTX 2.3 Video Pro · Audio to Video](https://doitong.com/developers/models/ltx-2.3/audio-to-video.md) (`ltx-2.3/audio-to-video`): $0.10 / second of input audio
- [LTX 2.3 22B](https://doitong.com/developers/models/ltx-2.3-22b/reference-video-to-video/lora.md) (`ltx-2.3-22b/reference-video-to-video/lora`): $0.00181 / megapixel of output video

## Links

- HTML page: https://doitong.com/developers/models/ltx-2.3/extend-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=ltx-2.3/extend-video
- Errors: https://doitong.com/developers/docs/errors
- Model details as JSON: https://api.doitong.com/v1/models/ltx-2.3/extend-video