# LTX-2.3 22B · Extend Video API

> Fortsætter en eksisterende video ud fra en prompt med genereret lyd og et valgfrit slutbillede

Tager `video_url` og en `prompt` og genererer en fortsættelse på `num_frames` frames (9 til 481). En valgfri `end_image_url` angiver, hvor forlængelsen slutter. `match_input_fps` bevarer kildens billedhastighed, `generate_audio` tilføjer lyd, og `video_size` er som standard auto. Outputtet kan være mp4, webm, mov eller 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/da/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 anvendt som grundlag for videogenerering. |
| `video_url` | `video` | string (video URL) | yes |  |  | URL, der peger på videoen, som skal forlænges. |
| `end_image_url` | `end_image` | string (image URL) \| null | no |  |  | Angiv et slut-frame-billede via URL for at definere, hvordan den forlængede video slutter. |
| `num_frames` |  | integer | no | `121` | 9 – 481 | Antal frames i det genererede output. |
| `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` | Dimensioner for den genererede video. |
| `generate_audio` |  | boolean | no | `true` |  | Styrer, om videoen indeholder genereret lyd. |
| `use_multiscale` |  | boolean | no | `true` |  | Multi-skala-generering for bedre sammenhæng og detaljer. Med True guider en foreløbig mindre video en anden generering, hvis størrelse opfylder eller overstiger de ønskede dimensioner. |
| `match_input_fps` |  | boolean | no | `true` |  | Tilsidesættelse af output-framehastigheden, som erstatter standard-FPS med kildevideoens FPS, når den er aktiveret. |
| `fps` |  | number | no | `24` | 1 – 60 | Billedhastighed for outputvideo målt i frames per sekund. |
| `num_inference_steps` |  | integer | no | `40` | 8 – 50 | Antal udførte inferenstrin. |
| `video_cfg_scale` |  | number | no | `3` | 1 – 20 | Videovejledningsindstilling: øg den for større sammenhæng og fokus i det genererede indhold. Bruger classifier-free guidance (CFG). |
| `video_stg_scale` |  | number | no | `0` | 0 – 20 | Styrer videoens sammenhæng og fokus via Spatiotemporal Guidance (STG)-skalaen; øg indstillingen for at styrke begge egenskaber. |
| `video_rescaling_scale` |  | number | no | `0.7` | 0 – 1 | Justering af videoskalering, der balancerer classifier-free og spatiotemporal guidance som et forhold. |
| `video_modality_scale` |  | number | no | `3` | 0 – 10 | Justering af videomodalitet, der balancerer videoens og lydens bidrag som et forhold. |
| `audio_cfg_scale` |  | number | no | `7` | 1 – 20 | Lydvejledningsindstilling: øg den for større sammenhæng og fokus i det genererede indhold. Bruger classifier-free guidance (CFG). |
| `audio_stg_scale` |  | number | no | `0` | 0 – 20 | Styrer lydens sammenhæng og fokus via Spatiotemporal Guidance (STG)-skalaen; øg indstillingen for at styrke begge egenskaber. |
| `audio_rescaling_scale` |  | number | no | `0.7` | 0 – 1 | Justering af lydskalering, der balancerer classifier-free og spatiotemporal guidance som et forhold. |
| `audio_modality_scale` |  | number | no | `3` | 0 – 10 | Justering af lydmodalitet, der balancerer videoens og lydens bidrag som et forhold. |
| `gradient_estimation_gamma` |  | number | no | `2` | 0 – 10 | Indstilling for estimering af støjfjernelsesgradienten: 0 deaktiverer estimering; ellers angiver værdien gamma. |
| `use_restart_sampling` |  | boolean | no | `false` |  | Genstart af sampling for muligvis bedre videokvalitet: aktivering tilføjer lidt støj ved hvert trin i støjfjernelsen. |
| `scheduler` |  | enum (string) | no | `ltx2` | `ltx2`, `linear_quadratic`, `beta` | Valg af scheduler. |
| `acceleration` |  | enum (string) | no | `regular` | `none`, `regular`, `high`, `full` | Accelerationsniveau anvendt på behandlingen. |
| `camera_lora` |  | enum (string) | no | `none` | `dolly_in`, `dolly_out`, `dolly_left`, `dolly_right`, `jib_up`, `jib_down`, `static`, `none` | Valg af kamera-LoRA til mere præcis styring af bevægelse i den genererede video end med kamerabevægelsesprompts alene. |
| `camera_lora_scale` |  | number | no | `1` | 0 – 1 | Kamera-LoRA-styrke til mere præcis styring af bevægelse i den genererede video end med kamerabevægelsesprompts alene. |
| `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` |  | Negativ prompt brugt under videogenerering. |
| `seed` |  | integer \| null | no |  |  | Seed-værdi, der initialiserer generering af tilfældige tal. |
| `enable_prompt_expansion` |  | boolean | no | `true` |  | Styrer, om promptudvidelse er aktiveret. |
| `enable_safety_checker` |  | boolean | no | `true` |  | Styrer, om sikkerhedskontrol er aktiveret. |
| `video_output_type` |  | enum (string) | no | `X264 (.mp4)` | `X264 (.mp4)`, `VP9 (.webm)`, `PRORES4444 (.mov)`, `GIF (.gif)` | Outputtype for den resulterende video. |
| `video_quality` |  | enum (string) | no | `high` | `low`, `medium`, `high`, `maximum` | Kvalitetsniveau for den resulterende video. |
| `video_write_mode` |  | enum (string) | no | `balanced` | `fast`, `balanced`, `small` | Skrivetilstand for den resulterende video. |
| `distill_lora_first_pass_scale` |  | number | no | `0.2` | 0 – 1 | Styrer første gennemløbs distill-LoRA-skalering; brug 0 til at deaktivere den. |
| `distill_lora_second_pass_scale` |  | number | no | `0.5` | 0 – 1 | Styrer distill-LoRA-skaleringen for hvert gennemløb efter det første. |
| `extend_direction` |  | enum (string) | no | `forward` | `forward`, `backward` | Den side af videoen, der skal forlænges: vælg 'backward' for at tilføje indhold før begyndelsen eller 'forward' for at tilføje indhold efter slutningen. |
| `num_context_frames` |  | integer | no | `25` | 0 – 121 | Frame-antal brugt til at give kontekst ved forlængelse af videoen. |
| `video_strength` |  | number | no | `1` | 0 – 1 | Friheden til at ændre videoindhold styres af denne konditioneringsstyrke: lavere indstillinger giver modellen større spillerum. |
| `audio_strength` |  | number | no | `1` | 0 – 1 | Friheden til at ændre lydindhold styres af denne konditioneringsstyrke: lavere indstillinger giver modellen større spillerum. |
| `end_image_strength` |  | number | no | `1` | 0 – 1 | Styrer, hvor meget slutbilledet påvirker den genererede 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-2.3-22b/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 produceret af modellen. |
| `seed` | integer | Seed-værdi brugt til at initialisere generering af tilfældige tal. |
| `prompt` | string | Prompt brugt til at styre genereringen. |

## 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