# Ltx 2.3 Quality · Extend Video API

> Meneruskan video ke hadapan atau ke belakang, dengan imej bingkai kunci penamat pilihan

Memanjangkan klip sedia ada dengan menjana rakaman baharu berdasarkan `prompt` yang diperlukan. `extend_direction` ialah `forward` untuk meneruskan dari penghujung atau `backward` untuk mencipta permulaan baharu. `num_context_frames` (9 hingga 121) menetapkan jumlah pertindihan sumber, manakala `num_frames` (9 hingga 481) menetapkan panjang segmen. `end_image_url` pilihan menetapkan bingkai utama terakhir, dan `match_input_fps` mengekalkan kadar bingkai sumber.

- Model id: `ltx-2.3-quality/extend-video`
- Made by: Lightricks
- Category: Video to Video
- Output: video
- Price per megapixel of your output video: $0.00241 / megapixel of output video (cheapest run $0.003 (3 API credits))
- Run: `POST https://api.doitong.com/v1/run/ltx-2.3-quality/extend-video`
- Quote: `POST https://api.doitong.com/v1/quote/ltx-2.3-quality/extend-video`
- Docs page: https://doitong.com/ms/developers/models/ltx-2.3-quality/extend-video

## Pricing

Price: **$0.00241 / megapixel of output video**. Price per megapixel 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.

The full example input below costs $0.27 = 270 API credits (112 MP output video × $0.002408).

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-quality/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 |
|---|---|---|---|---|---|---|
| `prompt` |  | string | yes |  |  | Prompt yang menyatakan sambungan video yang dikehendaki. |
| `video_url` | `video` | string (video URL) | yes |  |  | URL yang menunjuk kepada video yang akan dipanjangkan. |
| `extend_direction` |  | enum (string) | no | `forward` | `forward`, `backward` | Mod sambungan video: 'backward' mencipta permulaan baharu, manakala 'forward' meneruskan video melepasi penghujungnya. |
| `num_frames` |  | integer | no | `121` | 9 – 481 | Jumlah bingkai sambungan, tertakluk kepada belanjawan penjanaan stabil pada resolusi yang didarab dengan bingkai: pada 24 fps, kira-kira 20 saat untuk kelas 480p, 11 saat untuk kelas 720p atau 5 saat untuk kelas 1080p. Permintaan yang melebihi belanjawan mengembalikan 422; kurangkan `num_frames` atau pilih resolusi yang lebih kecil. Jumlah ini termasuk `num_context_frames` yang bertindih dengan sumber, jadi tempoh tambahan ialah kira-kira (`num_frames` - `num_context_frames`) / `frames_per_second` saat. |
| `num_context_frames` |  | integer | no | `25` | 9 – 121 | Jumlah bingkai sumber yang diminta untuk konteks/pertindihan sambungan, dihadkan oleh jumlah bingkai yang terkandung dalam sumber. Jumlah ini dibundarkan ke bawah agar sepadan dengan grid LTX 8k+1. |
| `end_image_url` | `end_image` | string (image URL) \| null | no |  |  | Imej bingkai utama pilihan yang menetapkan bingkai pertama baharu sambungan apabila memanjangkan ke belakang atau bingkai terakhirnya apabila memanjangkan ke hadapan. |
| `end_image_strength` |  | number | no | `1` | 0 – 1 | Kekuatan pengkondisian bingkai utama akhir pilihan: mengurangkannya memberikan model lebih banyak kebebasan, manakala 1.0 menguatkuasakan padanan tepat. |
| `resolution` |  | object {width, height} \| enum (string) | no | `auto` | `auto`, `square_hd`, `square`, `portrait_4_3`, `portrait_16_9`, `landscape_4_3`, `landscape_16_9` | Dimensi video yang dijana, diselaraskan kepada peningkatan 32px—contohnya, 1920x1080 menjadi 1888x1056—dengan sumber diubah saiz kepada dimensi ini untuk output yang dicantumkan. Sambungan stabil boleh menjadi lebih panjang pada resolusi lebih rendah dan lebih pendek pada resolusi lebih tinggi. Memilih 'auto' mengekalkan dimensi dan nisbah aspek sumber setakat yang dibenarkan oleh had LTX. |
| `match_input_fps` |  | boolean | no | `true` |  | Pemadanan kadar bingkai output dengan sumber apabila didayakan, mengatasi `frames_per_second`. FPS sumber dibundarkan kepada integer dan dihadkan kepada julat yang disokong. |
| `frames_per_second` |  | number | no | `24` | 1 – 60 | Kadar bingkai video output, diukur dalam bingkai sesaat. |
| `video_strength` |  | number | no | `1` | 0 – 1 | Kekuatan pengkondisian konteks sumber: mengurangkannya membenarkan lebih banyak kebebasan kepada model. Pada 1.0, bingkai yang bertindih kekal dikunci kepada sumber, menjadikan peralihan lancar. |
| `num_inference_steps` |  | integer | no | `15` | 8 – 30 | Tetapkan jumlah langkah inferens untuk dijalankan, sehingga 30; membiarkannya tidak berubah menggunakan 15. |
| `guidance_scale` |  | number | no | `1` | 1 – 20 | Laraskan panduan tanpa pengelas menggunakan skala ini; penalaan lalainya menyasarkan kualiti tinggi dan penjanaan pantas. |
| `generate_audio` |  | boolean | no | `true` |  | Togol audio sambungan: mati membiarkan segmen tambahan senyap sambil mengekalkan trek audio video sumber. Hidup menjana audio untuk sambungan dan melakukan silang pudar dengan sumber pada titik cantuman. |
| `negative_prompt` |  | string | no | `color distortion, overexposure, static, blurry details, subtitles, style, artwork, painting, frame, still, dim overall tone, worst quality, low quality, JPEG compression artifacts, ugly, mutilated, extra fingers, poorly drawn hands, poorly drawn face, deformed, disfigured, malformed limbs, fused fingers, motionless frame, cluttered background, three legs, crowded background, walking backwards` |  | Prompt negatif yang menyatakan perkara yang perlu dielakkan oleh penjanaan. |
| `seed` |  | integer \| null | no |  |  | Seed yang menjadikan penjanaan boleh diulang. Menetapkannya kepada None memilih seed secara rawak. |
| `enable_prompt_expansion` |  | boolean | no | `true` |  | Mengawal sama ada pengembangan prompt didayakan. |
| `enable_safety_checker` |  | boolean | no | `true` |  | Mengawal sama ada pemeriksaan keselamatan didayakan. |
| `video_quality` |  | enum (string) | no | `high` | `low`, `medium`, `high`, `maximum` | Praset kualiti yang digunakan pada video output. |
| `video_write_mode` |  | enum (string) | no | `balanced` | `fast`, `balanced`, `small` | Mod penulisan untuk video yang terhasil. |

File parameters (`video`, `end_image`) 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
{
  "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
  "video": "https://content.doitong.com/video/showcase/v3/gen_fox_cartoon.mp4"
}
```

A fuller example:

```json
{
  "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
  "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-quality/extend-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",
    "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-quality/extend-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",
    "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 = {
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
    "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-quality/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-quality/extend-video",
      "input": {
        "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
        "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-quality/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": 270,
    "usd": "0.27",
    "charged": 270,
    "refunded": 0
  },
  "input": {
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
    "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
    },
    "seed": 42,
    "prompt": "string"
  },
  "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 yang dihasilkan oleh model. |
| `seed` | integer | Seed sebenar yang digunakan semasa penjanaan. |
| `prompt` | string | Prompt penjanaan, termasuk sebarang pengembangan yang digunakan sebelum pemprosesan. |

## Related models

- [Ltx 2.3 Quality · Text to Video](https://doitong.com/developers/models/ltx-2.3-quality/text-to-video.md) (`ltx-2.3-quality/text-to-video`): $0.00241 / megapixel of output video
- [Ltx 2.3 Quality · Text to Video · LoRA](https://doitong.com/developers/models/ltx-2.3-quality/text-to-video/lora.md) (`ltx-2.3-quality/text-to-video/lora`): $0.00271 / megapixel of output video
- [Ltx 2.3 Quality · Image to Video](https://doitong.com/developers/models/ltx-2.3-quality/image-to-video.md) (`ltx-2.3-quality/image-to-video`): $0.00241 / megapixel of output video
- [Ltx 2.3 Quality · Image to Video · LoRA](https://doitong.com/developers/models/ltx-2.3-quality/image-to-video/lora.md) (`ltx-2.3-quality/image-to-video/lora`): $0.00271 / megapixel of output video
- [Ltx 2.3 Quality · Ingredient](https://doitong.com/developers/models/ltx-2.3-quality/ingredient.md) (`ltx-2.3-quality/ingredient`): $0.00241 / megapixel of output video
- [Ltx 2.3 Quality · Clean Plate](https://doitong.com/developers/models/ltx-2.3-quality/clean-plate.md) (`ltx-2.3-quality/clean-plate`): $0.00241 / megapixel of output video
- [Ltx 2.3 Quality · Colorization](https://doitong.com/developers/models/ltx-2.3-quality/colorization.md) (`ltx-2.3-quality/colorization`): $0.00241 / megapixel of output video
- [Ltx 2.3 Quality · Cross Eyed](https://doitong.com/developers/models/ltx-2.3-quality/cross-eyed.md) (`ltx-2.3-quality/cross-eyed`): $0.00241 / megapixel of output video

## Links

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