# Seedance 2.0 Fast — API Reference

Model ID: `model_bytedance-seedance-2-0-fast`

---

## 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_bytedance-seedance-2-0-fast`

### Parameters

| Parameter | Type | Required | Default | Description |
|-----------|------|----------|---------|-------------|
| `prompt` | string | - | - | Text prompt for video generation. Use "@" such as "@image1" or "@video1" to quickly reference selected images/videos. Prompt is optional if you provide a first frame or reference images/videos. |
| `image` | assetId | - | - | First frame image (frame mode). Mutually exclusive with reference images/videos. |
| `lastFrameImage` | assetId | - | - | Last frame image. Only valid when a first frame image is provided. |
| `referenceImages` | assetId[] | - | - | Reference images for multimodal mode (up to 9). Mutually exclusive with first frame. |
| `referenceVideos` | assetId[] | - | - | Reference videos for multimodal mode (up to 3). Mutually exclusive with first frame. |
| `referenceAudio` | assetId[] | - | - | Reference audio tracks (up to 3). Requires at least one reference image or video. |
| `duration` | number | - | `-1` | Duration in seconds (4–15), or Auto: with reference videos, bill at the longest reference clip length (clamped 4–15s). |
| `resolution` | string | - | `720p` | Output video resolution |
| `aspectRatio` | string | - | `adaptive` | Output aspect ratio |
| `generateAudio` | boolean | - | `true` | Whether to generate audio for the video |
| `seed` | number | - | - | Optional seed for reproducible results (0–4294967295). |

### Example Requests

**cURL**

```bash
curl -X POST "https://api.cloud.scenario.com/v1/generate/custom/model_bytedance-seedance-2-0-fast" \
  -H "Authorization: Basic $(echo -n '<API_KEY>:<API_SECRET>' | base64)" \
  -H "Content-Type: application/json" \
  --data-binary @- <<'EOF'
{
  "duration": -1,
  "resolution": "720p",
  "aspectRatio": "adaptive",
  "generateAudio": true
}
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_bytedance-seedance-2-0-fast"
headers = {
    "Authorization": f"Basic {token}",
    "Content-Type": "application/json"
}
payload = {
    "duration": -1,
    "resolution": "720p",
    "aspectRatio": "adaptive",
    "generateAudio": True
}

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

**JavaScript**

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

const body = {
  "duration": -1,
  "resolution": "720p",
  "aspectRatio": "adaptive",
  "generateAudio": true
};

const response = await fetch(
  "https://api.cloud.scenario.com/v1/generate/custom/model_bytedance-seedance-2-0-fast",
  {
    method: "POST",
    headers: {
      "Authorization": `Basic ${token}`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify(body),
  }
);

const data = await response.json();
console.info(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)*