# LTX-2.3 22B · Extend Video API

> Continuescha in video existent tenor in prompt, cun audio generà ed in maletg final facultativ

Prenda `video_url` ed in `prompt` e generescha ina cuntinuaziun da `num_frames` frames (9 fin 481). In `end_image_url` opziunal fixescha il punct final da l’extensiun. `match_input_fps` mantegna la frequenza da frames da la funtauna, `generate_audio` agiunta tun, e `video_size` è auto per standard. L’output po esser mp4, webm, mov u 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/rm/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 utilisà sco basa per la generaziun dal video. |
| `video_url` | `video` | string (video URL) | yes |  |  | URL che mussa al video che vegn prolungà. |
| `end_image_url` | `end_image` | string (image URL) \| null | no |  |  | Furnir tras URL in maletg dal frame final per definir co ch’il video prolungà finescha. |
| `num_frames` |  | integer | no | `121` | 9 – 481 | Dumber da frames per l'output generà. |
| `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` | Dimensiuns dal video generà. |
| `generate_audio` |  | boolean | no | `true` |  | Controlla sche il video cuntegna audio generà. |
| `use_multiscale` |  | boolean | no | `true` |  | Interrupziun per la generaziun multiscala per meglier coherenza e detagl. Cun True gida in video preliminar pli pitschen ina segunda generaziun, la quala cuntanscha u surpassa las dimensiuns dumandadas. |
| `match_input_fps` |  | boolean | no | `true` |  | Surdefiniziun dal frame-rate da l’output che remplazza il FPS standard cun il FPS dal video d’origin sch’ella è activada. |
| `fps` |  | number | no | `24` | 1 – 60 | Frame rate dal video d'output, mesirà en frames per secunda. |
| `num_inference_steps` |  | integer | no | `40` | 8 – 50 | Dumber da pass d'inferenza exequids. |
| `video_cfg_scale` |  | number | no | `3` | 1 – 20 | Configuraziun da guida dal video: auzai ella per dapli consistenza e focus en il cuntegn generà. Utilisescha classifier-free guidance (CFG). |
| `video_stg_scale` |  | number | no | `0` | 0 – 20 | Controlla la consistenza e il focus dal video tras la scala Spatiotemporal Guidance (STG); auzai la configuraziun per rinforzar omadus. |
| `video_rescaling_scale` |  | number | no | `0.7` | 0 – 1 | Ajustament da rescalaziun dal video per equilibrar la classifier-free guidance cun la guida spaziotemporala sco ratio. |
| `video_modality_scale` |  | number | no | `3` | 0 – 10 | Ajustament da la modalitad dal video per equilibrar las contribuziuns dal video e da l’audio sco ratio. |
| `audio_cfg_scale` |  | number | no | `7` | 1 – 20 | Configuraziun da guida da l’audio: auzai ella per dapli consistenza e focus en il cuntegn generà. Utilisescha classifier-free guidance (CFG). |
| `audio_stg_scale` |  | number | no | `0` | 0 – 20 | Controlla la consistenza e il focus da l’audio tras la scala Spatiotemporal Guidance (STG); auzai la configuraziun per rinforzar omadus. |
| `audio_rescaling_scale` |  | number | no | `0.7` | 0 – 1 | Ajustament da rescalaziun da l’audio per equilibrar la classifier-free guidance cun la guida spaziotemporala sco ratio. |
| `audio_modality_scale` |  | number | no | `3` | 0 – 10 | Ajustament da la modalitad da l’audio per equilibrar las contribuziuns dal video e da l’audio sco ratio. |
| `gradient_estimation_gamma` |  | number | no | `2` | 0 – 10 | Configuraziun da l’estimaziun dal gradient da denoisaziun: 0 deactivescha l’estimaziun; autramain definescha il valur gamma. |
| `use_restart_sampling` |  | boolean | no | `false` |  | Interrupziun dal sampling da restart per eventualmain meglier qualitad dal video: l’activaziun agiunta in pau canun ad ogni pass da denoisaziun. |
| `scheduler` |  | enum (string) | no | `ltx2` | `ltx2`, `linear_quadratic`, `beta` | Selecziun dal scheduler. |
| `acceleration` |  | enum (string) | no | `regular` | `none`, `regular`, `high`, `full` | Nivel d'acceleraziun applitgà a l'elavuraziun. |
| `camera_lora` |  | enum (string) | no | `none` | `dolly_in`, `dolly_out`, `dolly_left`, `dolly_right`, `jib_up`, `jib_down`, `static`, `none` | Selecziun da Camera LoRA per controllar il moviment en il video generà pli precis che mo cun prompts da moviment da camera. |
| `camera_lora_scale` |  | number | no | `1` | 0 – 1 | Furza da Camera LoRA per controllar il moviment en il video generà pli precis che mo cun prompts da moviment da camera. |
| `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 negativ utilisà durant la generaziun dal video. |
| `seed` |  | integer \| null | no |  |  | Valur da seed che inizialisescha la generaziun da nums casuals. |
| `enable_prompt_expansion` |  | boolean | no | `true` |  | Controlla sche l'expansiun dal prompt è activada. |
| `enable_safety_checker` |  | boolean | no | `true` |  | Controllescha sche la verificaziun da segirezza è activada. |
| `video_output_type` |  | enum (string) | no | `X264 (.mp4)` | `X264 (.mp4)`, `VP9 (.webm)`, `PRORES4444 (.mov)`, `GIF (.gif)` | Tip d'output dal video resultà. |
| `video_quality` |  | enum (string) | no | `high` | `low`, `medium`, `high`, `maximum` | Nivel da qualitad dal video resultà. |
| `video_write_mode` |  | enum (string) | no | `balanced` | `fast`, `balanced`, `small` | Modus da scriver per il video resultà. |
| `distill_lora_first_pass_scale` |  | number | no | `0.2` | 0 – 1 | Controllar la scala da distill LoRA dal prim pass; utilisar 0 per la deactivar. |
| `distill_lora_second_pass_scale` |  | number | no | `0.5` | 0 – 1 | Controllar la scala da distill LoRA per mintga pass suenter l’emprim. |
| `extend_direction` |  | enum (string) | no | `forward` | `forward`, `backward` | Lad dal video da prolungar: tscherner 'backward' per agiuntar cuntegn avant l’inizi u 'forward' per agiuntar cuntegn suenter la fin. |
| `num_context_frames` |  | integer | no | `25` | 0 – 121 | Dumber da frames utilisà per furnir context durant il prolungament dal video. |
| `video_strength` |  | number | no | `1` | 0 – 1 | La libertad da midar il cuntegn dal video vegn controllada da questa furza da cundiziunament: valurs pli pitschnas dattan al model dapli libertad. |
| `audio_strength` |  | number | no | `1` | 0 – 1 | La libertad da midar il cuntegn audio vegn controllada da questa furza da cundiziunament: valurs pli pitschnas dattan al model dapli libertad. |
| `end_image_strength` |  | number | no | `1` | 0 – 1 | Controllar quant che il maletg final influenzescha il video generà. |

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 producì dal model. |
| `seed` | integer | Valur da seed utilisà per inizialisar la generaziun da nums casuals. |
| `prompt` | string | Prompt utilisà per dirigir la generaziun. |

## 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