# Ltx 2.3 Quality · Extend Video API

> Heldur myndskeiði áfram fram á við eða aftur á bak, með valfrjálsri mynd af lykilramma í lokin

Lengir núverandi myndskeið með því að búa til nýtt myndefni samkvæmt nauðsynlegu `prompt`. `extend_direction` er `forward` til að halda áfram frá lokum eða `backward` til að búa til nýtt upphaf. `num_context_frames` (9 to 121) stillir hversu stór hluti upprunans skarast, en `num_frames` (9 to 481) stillir lengd hlutans. Valfrjálst `end_image_url` festir síðasta lykilrammann og `match_input_fps` heldur upprunalegum rammatíðni.

- 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/is/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 |  |  | Kvaðning sem tilgreinir æskda framhaldið á myndbandinu. |
| `video_url` | `video` | string (video URL) | yes |  |  | Slóð á myndbandið sem verður lengt. |
| `extend_direction` |  | enum (string) | no | `forward` | `forward`, `backward` | Hamur fyrir lengingu myndbands: 'backward' býr til nýtt upphaf, en 'forward' heldur myndbandinu áfram eftir lok þess. |
| `num_frames` |  | integer | no | `121` | 9 – 481 | Fjöldi ramma í lengingu, háður stöðugum efnisgerðar-fjárhagsramma fyrir upplausn margfaldaða með römmum: við 24 fps um 20 sekúndur fyrir 480p-flokk, 11 sekúndur fyrir 720p-flokk eða 5 sekúndur fyrir 1080p-flokk. Beiðnir sem fara yfir fjárhagsrammann skila 422; lækkaðu `num_frames` eða veldu minni upplausn. Fjöldinn inniheldur `num_context_frames` sem skarast við upprunann, þannig að viðbótarlengdin er um það bil (`num_frames` - `num_context_frames`) / `frames_per_second` sekúndur. |
| `num_context_frames` |  | integer | no | `25` | 9 – 121 | Fjöldi ramma úr upprunanum sem óskað er eftir fyrir samhengi/skörun lengingar, takmarkaður af fjölda ramma í upprunanum. Fjöldinn er námundaður niður svo hann passi við LTX-röðina 8k+1. |
| `end_image_url` | `end_image` | string (image URL) \| null | no |  |  | Valfrjáls lykilrammamynd sem stillir nýjan upphafsramma lengingar þegar lengt er aftur á bak eða lokaramma hennar þegar lengt er áfram. |
| `end_image_strength` |  | number | no | `1` | 0 – 1 | Valfrjáls skilyrðingarstyrkur lokalykilsramma: lækkun hans gefur líkaninu meira frelsi, en 1.0 framfylgir nákvæmri samsvörun. |
| `resolution` |  | object {width, height} \| enum (string) | no | `auto` | `auto`, `square_hd`, `square`, `portrait_4_3`, `portrait_16_9`, `landscape_4_3`, `landscape_16_9` | Mál myndaðs myndbands, samræmd við 32px þrep — til dæmis verður 1920x1080 að 1888x1056 — og uppruninn er endurstærður í þessi mál fyrir saumað úttak. Stöðugar lengingar geta verið lengri við lægri upplausn og styttri við hærri upplausn. Val á 'auto' heldur málum og hlutfalli upprunans eins langt og LTX-takmarkanir leyfa. |
| `match_input_fps` |  | boolean | no | `true` |  | Rammatíðni úttaks samræmd við upprunann þegar hún er virk og yfirskrifar `frames_per_second`. FPS upprunans er námundað að heiltölu og takmarkað við studda bilið. |
| `frames_per_second` |  | number | no | `24` | 1 – 60 | Rammatíðni úttaksvídeós, mæld í römmum á sekúndu. |
| `video_strength` |  | number | no | `1` | 0 – 1 | Skilyrðingarstyrkur samhengis uppruna: lækkun hans leyfir líkaninu meira frelsi. Við 1.0 haldast skörunar­rammarnir læstir við upprunann, sem gerir umskiptin saumlaus. |
| `num_inference_steps` |  | integer | no | `15` | 8 – 30 | Stilltu hversu mörg ályktunarskref eigi að keyra, allt að 30; ef þetta er óbreytt eru 15 notuð. |
| `guidance_scale` |  | number | no | `1` | 1 – 20 | Stilltu classifier-free guidance með þessum kvarða; sjálfgefin kvörðun hans miðar að bæði háum gæðum og hraðri efnisgerð. |
| `generate_audio` |  | boolean | no | `true` |  | Kveikja fyrir hljóði lengingar: óvirk stilling skilur viðbótarhlutann eftir hljóðlausan en heldur hljóðrás upprunamyndbandsins. Virk stilling býr til hljóð fyrir lenginguna og krossblandar það við upprunann á samskeytunum. |
| `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` |  | Neikvæð kvaðning sem tilgreinir hverju efnisgerðin á að forðast. |
| `seed` |  | integer \| null | no |  |  | Sáðgildi sem gerir efnisgerð endurtekningarhæfa. Ef það er stillt á None er sáðgildi valið af handahófi. |
| `enable_prompt_expansion` |  | boolean | no | `true` |  | Stýrir því hvort kvaðning sé útvíkkuð. |
| `enable_safety_checker` |  | boolean | no | `true` |  | Stýrir því hvort öryggisathugun sé virk. |
| `video_quality` |  | enum (string) | no | `high` | `low`, `medium`, `high`, `maximum` | Gæðaforstilling notuð á úttaksvídeóið. |
| `video_write_mode` |  | enum (string) | no | `balanced` | `fast`, `balanced`, `small` | Skrifhamur myndbandsins sem verður til. |

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} | Myndband sem líkanið býr til. |
| `seed` | integer | Raunverulegt fræ sem notað er við efnisgerð. |
| `prompt` | string | Efnisgerðarkvaðning, þar á meðal öll útvíkkun sem er beitt áður en hún er notuð. |

## 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