# LTX-2.3 22B · Extend Video API

> Continúa un video existente a partir de un prompt, con audio generado y una imagen final opcional

Acepta `video_url` y un `prompt`, y genera una continuación de `num_frames` fotogramas (9 a 481). Un `end_image_url` opcional establece dónde termina la extensión. `match_input_fps` mantiene la frecuencia de fotogramas de la fuente, `generate_audio` añade sonido y `video_size` tiene como valor predeterminado auto. El resultado puede ser mp4, webm, mov o GIF.

- Model id: `ltx-2.3-22b/extend-video`
- Made by: Lightricks
- Category: Video to Video
- Output: video
- Price per megapixel of your output video: $0.00161 / megapixel of output video (cheapest run $0.002 (2 API credits))
- Run: `POST https://api.doitong.com/v1/run/ltx-2.3-22b/extend-video`
- Quote: `POST https://api.doitong.com/v1/quote/ltx-2.3-22b/extend-video`
- Docs page: https://doitong.com/es/developers/models/ltx-2.3-22b/extend-video

## Pricing

Price: **$0.00161 / 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 $0.18 = 180 API credits (112 MP output video × $0.001605).

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-2.3-22b/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 utilizado como base para la generación de video. |
| `video_url` | `video` | string (video URL) | yes |  |  | URL que apunta al video que se extenderá. |
| `end_image_url` | `end_image` | string (image URL) \| null | no |  |  | Proporciona mediante URL una imagen del fotograma final para definir cómo termina el video extendido. |
| `num_frames` |  | integer | no | `121` | 9 – 481 | Cantidad de fotogramas de la salida generada. |
| `video_size` |  | object {width, height} \| enum (string) | no | `auto` | `auto`, `square_hd`, `square`, `portrait_4_3`, `portrait_16_9`, `landscape_4_3`, `landscape_16_9` | Dimensiones del video generado. |
| `generate_audio` |  | boolean | no | `true` |  | Controla si el video incluye audio generado. |
| `use_multiscale` |  | boolean | no | `true` |  | Alternador de generación multiescala para mejorar la coherencia y el detalle. Con True, un video preliminar más pequeño guía una segunda generación cuyo tamaño iguala o supera las dimensiones solicitadas. |
| `match_input_fps` |  | boolean | no | `true` |  | Sobrescritura de la velocidad de fotogramas de salida que reemplaza los FPS objetivo predeterminados por los FPS del video de origen cuando está activada. |
| `fps` |  | number | no | `24` | 1 – 60 | Velocidad de fotogramas del video de salida, medida en fotogramas por segundo. |
| `num_inference_steps` |  | integer | no | `40` | 8 – 50 | Cantidad de pasos de inferencia realizados. |
| `video_cfg_scale` |  | number | no | `3` | 1 – 20 | Configuración de guía del video: auméntala para obtener mayor coherencia y enfoque en el contenido generado. Usa guía sin clasificador (CFG). |
| `video_stg_scale` |  | number | no | `0` | 0 – 20 | Control de coherencia y enfoque del video mediante la escala de Guía espaciotemporal (STG); aumenta la configuración para reforzar ambas cualidades. |
| `video_rescaling_scale` |  | number | no | `0.7` | 0 – 1 | Ajuste de reescalado del video para equilibrar la guía sin clasificador y la guía espaciotemporal como proporción. |
| `video_modality_scale` |  | number | no | `3` | 0 – 10 | Ajuste de modalidad del video para equilibrar las contribuciones del video y el audio como proporción. |
| `audio_cfg_scale` |  | number | no | `7` | 1 – 20 | Configuración de guía del audio: auméntala para obtener mayor coherencia y enfoque en el contenido generado. Usa guía sin clasificador (CFG). |
| `audio_stg_scale` |  | number | no | `0` | 0 – 20 | Control de coherencia y enfoque del audio mediante la escala de Guía espaciotemporal (STG); aumenta la configuración para reforzar ambas cualidades. |
| `audio_rescaling_scale` |  | number | no | `0.7` | 0 – 1 | Ajuste de reescalado del audio para equilibrar la guía sin clasificador y la guía espaciotemporal como proporción. |
| `audio_modality_scale` |  | number | no | `3` | 0 – 10 | Ajuste de modalidad del audio para equilibrar las contribuciones del video y el audio como proporción. |
| `gradient_estimation_gamma` |  | number | no | `2` | 0 – 10 | Configuración de estimación del gradiente de eliminación de ruido: 0 desactiva la estimación; de lo contrario, el valor especifica gamma. |
| `use_restart_sampling` |  | boolean | no | `false` |  | Alternador de muestreo con reinicio para obtener potencialmente una mejor calidad de video: al habilitarlo se introduce un poco de ruido en cada paso de eliminación de ruido. |
| `scheduler` |  | enum (string) | no | `ltx2` | `ltx2`, `linear_quadratic`, `beta` | Selección del programador. |
| `acceleration` |  | enum (string) | no | `regular` | `none`, `regular`, `high`, `full` | Nivel de aceleración aplicado al procesamiento. |
| `camera_lora` |  | enum (string) | no | `none` | `dolly_in`, `dolly_out`, `dolly_left`, `dolly_right`, `jib_up`, `jib_down`, `static`, `none` | Selección de Camera LoRA para controlar el movimiento en el video generado con mayor precisión que usando solo prompt de movimiento de cámara. |
| `camera_lora_scale` |  | number | no | `1` | 0 – 1 | Intensidad de Camera LoRA para controlar el movimiento en el video generado con mayor precisión que usando solo prompt de movimiento de cámara. |
| `negative_prompt` |  | string | no | `news broadcast, 3d animation, computer graphics, pc game, console game, video game, cartoon, childish, watermark, logo, text, on screen text, subtitles, titles, signature, slowmo, static` |  | Prompt negativo utilizado durante la generación de video. |
| `seed` |  | integer \| null | no |  |  | Valor de semilla que inicializa la generación de números aleatorios. |
| `enable_prompt_expansion` |  | boolean | no | `true` |  | Controla si la expansión del prompt está habilitada. |
| `enable_safety_checker` |  | boolean | no | `true` |  | Controla si la comprobación de seguridad está activada. |
| `video_output_type` |  | enum (string) | no | `X264 (.mp4)` | `X264 (.mp4)`, `VP9 (.webm)`, `PRORES4444 (.mov)`, `GIF (.gif)` | Tipo de salida del video resultante. |
| `video_quality` |  | enum (string) | no | `high` | `low`, `medium`, `high`, `maximum` | Nivel de calidad del video resultante. |
| `video_write_mode` |  | enum (string) | no | `balanced` | `fast`, `balanced`, `small` | Modo de escritura del video resultante. |
| `distill_lora_first_pass_scale` |  | number | no | `0.2` | 0 – 1 | Controla la escala de distill LoRA de la primera pasada; usa 0 para desactivarla. |
| `distill_lora_second_pass_scale` |  | number | no | `0.5` | 0 – 1 | Controla la escala de distill LoRA para cada pasada posterior a la primera. |
| `extend_direction` |  | enum (string) | no | `forward` | `forward`, `backward` | Lado del video que se extenderá: elige 'backward' para añadir contenido antes de su inicio o 'forward' para añadir contenido después de su final. |
| `num_context_frames` |  | integer | no | `25` | 0 – 121 | Número de fotogramas utilizado para proporcionar contexto al extender el video. |
| `video_strength` |  | number | no | `1` | 0 – 1 | Esta intensidad de condicionamiento controla la libertad para modificar el contenido del video: los valores menores permiten al modelo mayor libertad. |
| `audio_strength` |  | number | no | `1` | 0 – 1 | Esta intensidad de condicionamiento controla la libertad para modificar el contenido del audio: los valores menores permiten al modelo mayor libertad. |
| `end_image_strength` |  | number | no | `1` | 0 – 1 | Controla cuánto influye la imagen final en el video generado. |

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-2.3-22b/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-2.3-22b/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-2.3-22b/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-2.3-22b/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-2.3-22b/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": 180,
    "usd": "0.18",
    "charged": 180,
    "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,
      "width": 1024,
      "height": 768,
      "fps": 1.0,
      "duration": 5,
      "num_frames": 1
    },
    "seed": 42,
    "prompt": "A woman stands still amid a busy neon-lit street at night. The camera slowly dollies in toward her face as people blur past, their motion emphasizing her calm presence. City lights flicker and reflections shift across her denim jacket."
  },
  "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} | Video producido por el modelo. |
| `seed` | integer | Valor de seed utilizado para inicializar la generación de números aleatorios. |
| `prompt` | string | Prompt utilizado para guiar la generación. |

## Related models

- [LTX-2.3 22B · Text to Video](https://doitong.com/developers/models/ltx-2.3-22b/text-to-video.md) (`ltx-2.3-22b/text-to-video`): $0.00161 / megapixel of output video
- [LTX-2.3 22B · Text to Video · LoRA](https://doitong.com/developers/models/ltx-2.3-22b/text-to-video/lora.md) (`ltx-2.3-22b/text-to-video/lora`): $0.00181 / megapixel of output video
- [LTX-2.3 22B · Image to Video](https://doitong.com/developers/models/ltx-2.3-22b/image-to-video.md) (`ltx-2.3-22b/image-to-video`): $0.00161 / megapixel of output video
- [LTX-2.3 22B · Image to Video · LoRA](https://doitong.com/developers/models/ltx-2.3-22b/image-to-video/lora.md) (`ltx-2.3-22b/image-to-video/lora`): $0.00181 / megapixel of output video
- [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
- [LTX-2.3 22B · Extend Video · LoRA](https://doitong.com/developers/models/ltx-2.3-22b/extend-video/lora.md) (`ltx-2.3-22b/extend-video/lora`): $0.00181 / megapixel of output video
- [LTX-2.3 22B · Reference Video to Video](https://doitong.com/developers/models/ltx-2.3-22b/reference-video-to-video.md) (`ltx-2.3-22b/reference-video-to-video`): $0.00161 / megapixel of output video
- [LTX-2.3 22B · Video to Video](https://doitong.com/developers/models/ltx-2.3-22b/video-to-video.md) (`ltx-2.3-22b/video-to-video`): $0.00161 / megapixel of output video

## Links

- HTML page: https://doitong.com/developers/models/ltx-2.3-22b/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-2.3-22b/extend-video
- Errors: https://doitong.com/developers/docs/errors
- Model details as JSON: https://api.doitong.com/v1/models/ltx-2.3-22b/extend-video