# Ltx 2.3 Quality · Extend Video API

> Turpina video uz priekšu vai atpakaļ, pēc izvēles izmantojot beigu atslēgkadru attēlu

Paplašina esošu klipu, ģenerējot jaunus kadrus, vadoties pēc obligātā `prompt`. `extend_direction` vērtība `forward` turpina no beigām, bet `backward` izveido jaunu sākumu. `num_context_frames` (9 līdz 121) nosaka avota pārklājuma apjomu, bet `num_frames` (9 līdz 481) — segmenta garumu. Neobligāts `end_image_url` nosaka beigu atslēgas kadru, bet `match_input_fps` saglabā avota kadru nomaiņas ātrumu.

- 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/lv/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 |  |  | Uzvedne, kas norāda vēlamo video turpinājumu. |
| `video_url` | `video` | string (video URL) | yes |  |  | URL, kas norāda uz pagarināmo video. |
| `extend_direction` |  | enum (string) | no | `forward` | `forward`, `backward` | Video pagarināšanas režīms: 'backward' izveido jaunu sākumu, bet 'forward' turpina video aiz tā beigām. |
| `num_frames` |  | integer | no | `121` | 9 – 481 | Pagarinājuma kadru skaits, uz kuru attiecas stabilas ģenerēšanas budžets, kas ierobežo izšķirtspējas un kadru skaita reizinājumu: pie 24 fps aptuveni 20 sekundes 480p klases, 11 sekundes 720p klases vai 5 sekundes 1080p klases saturam. Budžeta pārsniegšana atgriež 422; samaziniet `num_frames` vai izvēlieties mazāku izšķirtspēju. Skaitā ietilpst `num_context_frames`, kas pārklājas ar avotu, tāpēc pievienotais ilgums ir aptuveni (`num_frames` - `num_context_frames`) / `frames_per_second` sekundes. |
| `num_context_frames` |  | integer | no | `25` | 9 – 121 | Avota kadru skaits, kas pieprasīts pagarinājuma kontekstam/pārklājumam un ierobežots ar avotā esošo kadru skaitu. Skaits tiek noapaļots uz leju, lai atbilstu LTX režģim 8k+1. |
| `end_image_url` | `end_image` | string (image URL) \| null | no |  |  | Neobligāts atslēgkadru attēls, kas nosaka jauno pirmo kadru, pagarinot atpakaļ, vai pēdējo kadru, pagarinot uz priekšu. |
| `end_image_strength` |  | number | no | `1` | 0 – 1 | Neobligāts beigu atslēgkadra nosacījuma stiprums: samazināšana ļauj modelim lielāku brīvību, bet 1.0 nodrošina precīzu atbilstību. |
| `resolution` |  | object {width, height} \| enum (string) | no | `auto` | `auto`, `square_hd`, `square`, `portrait_4_3`, `portrait_16_9`, `landscape_4_3`, `landscape_16_9` | Ģenerētā video izmēri, kas pielāgoti 32px soļiem — piemēram, 1920x1080 kļūst par 1888x1056 — un avots tiek mainīts uz šiem izmēriem saliktajai izvadei. Stabilie pagarinājumi var būt garāki ar zemāku izšķirtspēju un īsāki ar augstāku. Izvēloties 'auto', tiek saglabāti avota izmēri un malu attiecība, ciktāl to pieļauj LTX ierobežojumi. |
| `match_input_fps` |  | boolean | no | `true` |  | Kadru ātruma saskaņošana ar avotu, ja iespējota, aizstājot `frames_per_second`. Avota FPS tiek noapaļots līdz veselam skaitlim un ierobežots līdz atbalstītajam diapazonam. |
| `frames_per_second` |  | number | no | `24` | 1 – 60 | Izvades video kadru ātrums, mērīts kadros sekundē. |
| `video_strength` |  | number | no | `1` | 0 – 1 | Avota konteksta nosacījuma stiprums: samazināšana ļauj modelim lielāku brīvību. Pie 1.0 pārklājošie kadri paliek piesaistīti avotam, padarot pāreju nemanāmu. |
| `num_inference_steps` |  | integer | no | `15` | 8 – 30 | Iestatiet izpildāmo secināšanas soļu skaitu, nepārsniedzot 30; nemainot šo vērtību, tiek izmantoti 15. |
| `guidance_scale` |  | number | no | `1` | 1 – 20 | Pielāgojiet classifier-free guidance, izmantojot šo mērogu; tā noklusējuma regulējums ir paredzēts augstai kvalitātei un ātrai ģenerēšanai. |
| `generate_audio` |  | boolean | no | `true` |  | Pagarinājuma audio pārslēgs: izslēgts atstāj pievienoto segmentu klusu, saglabājot avota video audio celiņu. Ieslēgts ģenerē pagarinājuma audio un savienojuma vietā to sapludina ar avotu. |
| `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` |  | Negatīvā uzvedne, kas norāda, no kā ģenerēšanā jāizvairās. |
| `seed` |  | integer \| null | no |  |  | Sēkla, kas padara ģenerēšanu atkārtojamu. Iestatot None, sēkla tiek izvēlēta nejauši. |
| `enable_prompt_expansion` |  | boolean | no | `true` |  | Kontrolē, vai ir iespējota uzvednes paplašināšana. |
| `enable_safety_checker` |  | boolean | no | `true` |  | Nosaka, vai drošības pārbaude ir iespējota. |
| `video_quality` |  | enum (string) | no | `high` | `low`, `medium`, `high`, `maximum` | Izvades video pielietotais kvalitātes iestatījums. |
| `video_write_mode` |  | enum (string) | no | `balanced` | `fast`, `balanced`, `small` | Iegūtā video ierakstīšanas režīms. |

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} | Modeļa izveidotais video. |
| `seed` | integer | Faktiskā sēkla, kas izmantota ģenerēšanas laikā. |
| `prompt` | string | Ģenerēšanas uzvedne, tostarp jebkāda pirms izmantošanas veikta paplašināšana. |

## 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