# LTX-2 19b Video to Video — API Reference

Model ID: `model_ltx-2-19b-video-to-video`

---

## Authentication

Scenario API uses HTTP Basic Auth. Encode your credentials in Base64 and pass them as the `Authorization` header.

```
Authorization: Basic base64("<API_KEY>:<API_SECRET>")
```

- **API_KEY** and **API_SECRET** are found in your [Scenario Project Settings](https://app.scenario.com/team&tab=project_api_keys) under API Keys.
- In shell: `$(echo -n '<API_KEY>:<API_SECRET>' | base64)`
- In JavaScript: `btoa("<API_KEY>:<API_SECRET>")`
- In Python: `base64.b64encode(f"{api_key}:{api_secret}".encode()).decode()`

---

## Generate

**Endpoint:** `POST https://api.cloud.scenario.com/v1/generate/custom/model_ltx-2-19b-video-to-video`

### Parameters

| Parameter | Type | Required | Default | Description |
|-----------|------|----------|---------|-------------|
| `prompt` | string | yes | - | Text prompt for video generation |
| `videoStrength` | number | - | `1` | Reference video conditioning strength (0-1). Higher = more faithful to input video structure. |
| `imageStrength` | number | - | `1` | First-frame image conditioning strength (0-1). |
| `negativePrompt` | string | - | - | Negative prompt to guide what to avoid in generation |
| `resolution` | string | - | `auto` | Video resolution. 'Match Input' replicates input video dimensions (recommended). |
| `width` | number | - | - | Explicit video width in pixels. Must be used with height. Rounded to multiple of 64. |
| `height` | number | - | - | Explicit video height in pixels. Must be used with width. Rounded to multiple of 64. |
| `cameraMotion` | string | - | `none` | Camera movement type in the generated video. |
| `cameraMotionStrength` | number | - | `1` | Strength of camera motion (0-2). Higher values = stronger effect. |
| `duration` | number | - | - | Output video duration in seconds (3-20). Leave empty to match input video. |
| `aspectRatio` | string | - | `auto` | Video aspect ratio. 'Match Input' detects from input video (recommended). |
| `fps` | number | - | - | Output frame rate (1-60 fps). Leave empty to match input video. |
| `audioSource` | string | - | `original` | Audio for output: copy from input, generate new, or none. |
| `modality` | string | - | `none` | IC-LoRA control: canny (edges), depth, pose (skeleton), detailer, or none. |
| `modalityStrength` | number | - | `1` | Strength of IC-LoRA modality (0-2). Higher values = stronger control. |
| `numInferenceSteps` | number | - | `40` | Number of inference steps. Higher = better quality, slower. |
| `guidanceScale` | number | - | `3` | Classifier-free guidance scale. Higher = stronger prompt adherence. |
| `enhancePrompt` | boolean | - | `false` | Use Gemma to enhance the prompt for better video generation |
| `seed` | number | - | - | Random seed for reproducibility. Leave blank for random. |

### Example Requests

**cURL**

```bash
curl -X POST "https://api.cloud.scenario.com/v1/generate/custom/model_ltx-2-19b-video-to-video" \
  -H "Authorization: Basic $(echo -n '<API_KEY>:<API_SECRET>' | base64)" \
  -H "Content-Type: application/json" \
  --data-binary @- <<'EOF'
{
  "prompt": "A fantasy landscape",
  "videoStrength": 1,
  "imageStrength": 1,
  "resolution": "auto",
  "cameraMotion": "none",
  "cameraMotionStrength": 1,
  "aspectRatio": "auto",
  "audioSource": "original",
  "modality": "none",
  "modalityStrength": 1,
  "numInferenceSteps": 40,
  "guidanceScale": 3,
  "enhancePrompt": false
}
EOF
```

**Python**

```python
import requests
import base64

api_key = "<API_KEY>"
api_secret = "<API_SECRET>"
token = base64.b64encode(f"{api_key}:{api_secret}".encode()).decode()

url = "https://api.cloud.scenario.com/v1/generate/custom/model_ltx-2-19b-video-to-video"
headers = {
    "Authorization": f"Basic {token}",
    "Content-Type": "application/json"
}
payload = {
    "prompt": "A fantasy landscape",
    "videoStrength": 1,
    "imageStrength": 1,
    "resolution": "auto",
    "cameraMotion": "none",
    "cameraMotionStrength": 1,
    "aspectRatio": "auto",
    "audioSource": "original",
    "modality": "none",
    "modalityStrength": 1,
    "numInferenceSteps": 40,
    "guidanceScale": 3,
    "enhancePrompt": False
}

response = requests.post(url, headers=headers, json=payload)
print(response.json())
```

**JavaScript**

```javascript
const token = btoa("<API_KEY>:<API_SECRET>");

const body = {
  "prompt": "A fantasy landscape",
  "videoStrength": 1,
  "imageStrength": 1,
  "resolution": "auto",
  "cameraMotion": "none",
  "cameraMotionStrength": 1,
  "aspectRatio": "auto",
  "audioSource": "original",
  "modality": "none",
  "modalityStrength": 1,
  "numInferenceSteps": 40,
  "guidanceScale": 3,
  "enhancePrompt": false
};

const response = await fetch(
  "https://api.cloud.scenario.com/v1/generate/custom/model_ltx-2-19b-video-to-video",
  {
    method: "POST",
    headers: {
      "Authorization": `Basic ${token}`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify(body),
  }
);

const data = await response.json();
console.log(data);
```

---

## Retrieve Results

After submitting a generation request, you receive a `jobId`. Poll the job status endpoint until the job completes.

**Endpoint:** `GET https://api.cloud.scenario.com/v1/jobs/{jobId}`

**Headers:**
```
Authorization: Basic base64("<API_KEY>:<API_SECRET>")
```

Poll until `job.status` is `"success"`. The generated asset IDs are in `job.metadata.assetIds`.

**Example response:**
```json
{
  "job": {
    "jobId": "job_abc123",
    "status": "success",
    "metadata": {
      "assetIds": [
        "asset_abc123"
      ]
    }
  }
}
```

> **Important:** Generated asset URLs are **temporary** and expire after a short period. Download and store any images you wish to keep before the URL expires. More info: [Content Delivery Network (CDN)](https://docs.scenario.com/docs/content-delivery-network-cdn).

---

*Generated by [Scenario](https://app.scenario.com)*