> ## Documentation Index
> Fetch the complete documentation index at: https://docs.routerbase.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Doubao-Seedance 2.0 Fast — Text to Video

> Accelerated, lower-cost Doubao-Seedance 2.0 — 720p-only text to video.

|              |                                      |
| ------------ | ------------------------------------ |
| **Model ID** | `bytedance/seedance-2-fast-t2v`      |
| **Family**   | `seedance-2-fast`                    |
| **Task**     | `text-to-video`                      |
| **Modality** | Video                                |
| **Upstream** | ByteDance Doubao-Seedance 2.0 (Fast) |

<Note>
  The Fast tier is accelerated and lower-cost but supports **720p only** —
  `resolution: "1080p"` is rejected. Use the [Standard model](/bytedance-seedance-2-api/text-to-video) for 1080p.
</Note>

## Endpoint

```http theme={null}
POST https://routerbase.com/v1/videos/generations
```

Async — returns `{id, status: "pending"}`; poll `GET /v1/videos/generations/{id}` until `success` or `failed`.

## Parameters

<ParamField body="prompt" type="string" required>
  Text prompt describing the video. Max 5000 characters.
</ParamField>

<ParamField body="resolution" type="&#x22;720p&#x22;" default="&#x22;720p&#x22;">
  Fast is 720p-only.
</ParamField>

<ParamField body="ratio" type="string" default="&#x22;16:9&#x22;">
  Aspect ratio: `16:9`, `9:16`, `1:1`, `4:3`, `3:4`, `21:9`.
</ParamField>

<ParamField body="duration" type="integer" default="5">
  Clip length in seconds. Range `[3, 12]`.
</ParamField>

<ParamField body="seed" type="integer">
  Reproducibility seed. Range `[0, 2147483647]`.
</ParamField>

## Example

```bash theme={null}
curl https://routerbase.com/v1/videos/generations \
  -H "Authorization: Bearer $ROUTERBASE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "bytedance/seedance-2-fast-t2v",
    "prompt": "a calm beach at sunrise, cinematic",
    "duration": 5
  }'
```

## See also

Full request/response schema and pricing: [Video Generation](/api-reference/videos).