# Ltx 2.3 Quality · Extend Video API

> Melanjutkan video ke depan atau ke belakang, dengan gambar keyframe akhir opsional

Memperpanjang klip yang ada dengan membuat footage baru berdasarkan `prompt` wajib. `extend_direction` adalah `forward` untuk melanjutkan dari akhir atau `backward` untuk membuat awal baru. `num_context_frames` (9 hingga 121) menentukan seberapa banyak sumber yang tumpang tindih, dan `num_frames` (9 hingga 481) menentukan panjang segmen. `end_image_url` opsional menetapkan bingkai kunci akhir, sedangkan `match_input_fps` mempertahankan laju 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/id/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 menentukan kelanjutan video yang diinginkan. |
| `video_url` | `video` | string (video URL) | yes |  |  | URL yang mengarah ke video yang akan diperpanjang. |
| `extend_direction` |  | enum (string) | no | `forward` | `forward`, `backward` | Mode perpanjangan video: 'backward' membuat awal baru, sedangkan 'forward' melanjutkan video setelah akhirnya. |
| `num_frames` |  | integer | no | `121` | 9 – 481 | Jumlah bingkai perpanjangan, yang tunduk pada anggaran pembuatan stabil berdasarkan hasil perkalian resolusi dan bingkai: pada 24 fps, sekitar 20 detik untuk kelas 480p, 11 detik untuk kelas 720p, atau 5 detik untuk kelas 1080p. Permintaan yang melebihi anggaran mengembalikan 422; kurangi `num_frames` atau pilih resolusi yang lebih kecil. Jumlah ini mencakup `num_context_frames` yang tumpang tindih dengan sumber, sehingga durasi tambahan kira-kira (`num_frames` - `num_context_frames`) / `frames_per_second` detik. |
| `num_context_frames` |  | integer | no | `25` | 9 – 121 | Jumlah bingkai sumber yang diminta untuk konteks/tumpang tindih perpanjangan, dibatasi oleh jumlah bingkai yang dimiliki sumber. Jumlahnya dibulatkan ke bawah agar sesuai dengan grid LTX sebesar 8k+1. |
| `end_image_url` | `end_image` | string (image URL) \| null | no |  |  | Gambar keyframe opsional yang menetapkan bingkai pertama baru perpanjangan saat memperpanjang ke belakang atau bingkai terakhir saat memperpanjang ke depan. |
| `end_image_strength` |  | number | no | `1` | 0 – 1 | Kekuatan conditioning keyframe akhir opsional: menguranginya memberi model lebih banyak kebebasan, sedangkan 1.0 memaksakan kecocokan persis. |
| `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 dibuat, diselaraskan ke kenaikan 32px—misalnya, 1920x1080 menjadi 1888x1056—dengan sumber diubah ukurannya ke dimensi ini untuk output yang digabungkan. Perpanjangan stabil dapat lebih panjang pada resolusi rendah dan lebih pendek pada resolusi tinggi. Memilih 'auto' mempertahankan dimensi dan rasio aspek sumber sejauh diizinkan oleh batas LTX. |
| `match_input_fps` |  | boolean | no | `true` |  | Pencocokan laju bingkai output dengan sumber saat diaktifkan, menggantikan `frames_per_second`. FPS sumber dibulatkan menjadi bilangan bulat dan dibatasi pada rentang yang didukung. |
| `frames_per_second` |  | number | no | `24` | 1 – 60 | Laju bingkai video output, diukur dalam bingkai per detik. |
| `video_strength` |  | number | no | `1` | 0 – 1 | Kekuatan conditioning konteks sumber: menguranginya memberi model lebih banyak kebebasan. Pada 1.0, bingkai yang tumpang tindih tetap terkunci pada sumber sehingga transisi menjadi mulus. |
| `num_inference_steps` |  | integer | no | `15` | 8 – 30 | Atur jumlah langkah inferensi yang dijalankan, hingga 30; jika tidak diubah, nilainya 15. |
| `guidance_scale` |  | number | no | `1` | 1 – 20 | Sesuaikan classifier-free guidance menggunakan skala ini; penyetelan bawaannya menargetkan kualitas tinggi sekaligus pembuatan cepat. |
| `generate_audio` |  | boolean | no | `true` |  | Sakelar audio perpanjangan: nonaktif membuat segmen tambahan tanpa suara sambil mempertahankan trek audio video sumber. Aktif menghasilkan audio untuk perpanjangan dan melakukan crossfade dengan sumber pada titik penyambungan. |
| `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 menentukan hal-hal yang harus dihindari dalam pembuatan. |
| `seed` |  | integer \| null | no |  |  | Seed yang membuat pembuatan dapat direproduksi. Mengaturnya ke None akan memilih seed secara acak. |
| `enable_prompt_expansion` |  | boolean | no | `true` |  | Mengontrol apakah perluasan prompt diaktifkan. |
| `enable_safety_checker` |  | boolean | no | `true` |  | Mengontrol apakah pemeriksaan keamanan diaktifkan. |
| `video_quality` |  | enum (string) | no | `high` | `low`, `medium`, `high`, `maximum` | Preset kualitas yang diterapkan pada video output. |
| `video_write_mode` |  | enum (string) | no | `balanced` | `fast`, `balanced`, `small` | Mode penulisan untuk video yang dihasilkan. |

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 model. |
| `seed` | integer | Seed aktual yang diterapkan selama pembuatan. |
| `prompt` | string | Prompt pembuatan, termasuk ekspansi yang diterapkan sebelum digunakan. |

## 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