# Ltx 2.3 Quality · Extend Video API

> Ipinagpapatuloy ang video pasulong o paatras, na may opsyonal na end keyframe na larawan

Pinapahaba ang isang clip sa pamamagitan ng pagbuo ng bagong footage gamit ang kinakailangang `prompt`. Ang `extend_direction` ay `forward` para magpatuloy mula sa dulo o `backward` para gumawa ng bagong simula. Tinutukoy ng `num_context_frames` (9 hanggang 121) kung gaano kalaking bahagi ng source ang magkakapatong, at ng `num_frames` (9 hanggang 481) ang haba ng segment. Maaaring magtakda ang opsyonal na `end_image_url` ng huling keyframe, habang pinananatili ng `match_input_fps` ang frame rate ng source.

- 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/fil/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 na tumutukoy sa nais na pagpapatuloy ng video. |
| `video_url` | `video` | string (video URL) | yes |  |  | URL na tumutukoy sa video na palalawigin. |
| `extend_direction` |  | enum (string) | no | `forward` | `forward`, `backward` | Mode ng pagpapalawak ng video: gumagawa ang 'backward' ng bagong simula, habang ipinagpapatuloy ng 'forward' ang video lampas sa dulo nito. |
| `num_frames` |  | integer | no | `121` | 9 – 481 | Bilang ng frame para sa extension, na sakop ng stable-generation badyet sa resolution na minultiply sa mga frame: sa 24 fps, humigit-kumulang 20 segundo para sa 480p-class, 11 segundo para sa 720p-class, o 5 segundo para sa 1080p-class. Nagbabalik ng 422 ang mga kahilingang lumalampas sa badyet; bawasan ang `num_frames` o pumili ng mas maliit na resolution. Kasama sa bilang ang `num_context_frames` na nag-o-overlap sa source, kaya ang idinagdag na tagal ay humigit-kumulang (`num_frames` - `num_context_frames`) / `frames_per_second` segundo. |
| `num_context_frames` |  | integer | no | `25` | 9 – 121 | Bilang ng source frame na hinihingi para sa context/overlap ng extension, na nililimitahan ng dami ng frame na nasa source. Ibinababa ang rounding ng bilang upang umangkop sa LTX grid na 8k+1. |
| `end_image_url` | `end_image` | string (image URL) \| null | no |  |  | Opsyonal na keyframe larawan na nagtatakda ng bagong unang frame ng extension kapag backward o huling frame kapag forward. |
| `end_image_strength` |  | number | no | `1` | 0 – 1 | Opsyonal na conditioning strength ng end-keyframe: nagbibigay ng mas malaking kalayaan sa modelo ang pagbabawas nito, habang nagpapatupad ang 1.0 ng eksaktong pagtutugma. |
| `resolution` |  | object {width, height} \| enum (string) | no | `auto` | `auto`, `square_hd`, `square`, `portrait_4_3`, `portrait_16_9`, `landscape_4_3`, `landscape_16_9` | Mga sukat ng nabuong video, naka-align sa mga increment na 32px—halimbawa, nagiging 1888x1056 ang 1920x1080—at nire-resize ang source sa mga sukat na ito para sa stitched output. Mas mahaba ang stable extension sa mas mababang resolution at mas maikli sa mas mataas. Pinananatili ng pagpiling 'auto' ang mga sukat at aspect ratio ng source hangga't pinapahintulutan ng mga limitasyon ng LTX. |
| `match_input_fps` |  | boolean | no | `true` |  | Pagtutugma ng output frame rate sa source kapag naka-enable, na ino-override ang `frames_per_second`. Niroround ang source FPS sa integer at nililimitahan sa suportadong range. |
| `frames_per_second` |  | number | no | `24` | 1 – 60 | Frame rate ng output video, na sinusukat sa frames per segundo. |
| `video_strength` |  | number | no | `1` | 0 – 1 | Conditioning strength ng source context: nagbibigay ng mas malaking kalayaan sa modelo ang pagbabawas nito. Sa 1.0, nananatiling naka-lock sa source ang magkakapatong na frame, kaya seamless ang transition. |
| `num_inference_steps` |  | integer | no | `15` | 8 – 30 | Itakda kung ilang inference step ang tatakbuhin, hanggang 30; kapag hindi binago, 15 ang ginagamit. |
| `guidance_scale` |  | number | no | `1` | 1 – 20 | Ayusin ang classifier-free guidance gamit ang scale na ito; nakatuon ang default tuning nito sa mataas na kalidad at mabilis na pagbuo. |
| `generate_audio` |  | boolean | no | `true` |  | Toggle ng audio para sa extension: iniiwang tahimik ng off ang idinagdag na segment habang pinananatili ang audio track ng source video. Gumagawa ang On ng audio para sa extension at nagka-crossfade ito sa source sa dugtungan. |
| `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` |  | Negative prompt na tumutukoy sa dapat iwasan ng pagbuo. |
| `seed` |  | integer \| null | no |  |  | Seed na ginagawang reproducible ang pagbuo. Ang pagtatakda nito sa None ay random na pumipili ng seed. |
| `enable_prompt_expansion` |  | boolean | no | `true` |  | Kinokontrol kung naka-enable ang prompt expansion. |
| `enable_safety_checker` |  | boolean | no | `true` |  | Kinokontrol kung pinapagana ang safety checking. |
| `video_quality` |  | enum (string) | no | `high` | `low`, `medium`, `high`, `maximum` | Quality preset na inilalapat sa output video. |
| `video_write_mode` |  | enum (string) | no | `balanced` | `fast`, `balanced`, `small` | Write mode para sa resultang video. |

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} | Videong ginawa ng modelo. |
| `seed` | integer | Aktuwal na seed na ginagamit habang bumubuo. |
| `prompt` | string | Prompt sa pagbuo, kabilang ang anumang expansion na inilapat bago gamitin. |

## 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