> ## 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.

# Kling v3.0 4K — Image to Video

> Animate a reference image into a 4K video with Kuaishou Kling 3.0. Optional synthesized audio.

|              |                            |
| ------------ | -------------------------- |
| **Model ID** | `kuaishou/kling-v3-4k-i2v` |
| **Family**   | `kling-v3-novita`          |
| **Task**     | `image-to-video`           |
| **Modality** | Video                      |
| **Upstream** | Kuaishou Kling 3.0 (4K)    |

<Note>
  `sound: true` switches the per-second billing rate from **$0.399/s**
      (no audio) to **$0.599/s** (with audio). The default is `false`.
</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 motion / scene changes. Max 2500 characters.
</ParamField>

<ParamField body="image_urls" type="string[]" required>
  Exactly one source-image URL (HTTPS, PNG / JPEG).
</ParamField>

<ParamField body="end_image" type="string">
  Optional public HTTPS URL pinning the final frame of the output.
</ParamField>

<ParamField body="duration" type="integer" default="5">
  Length of the generated clip in seconds. Range `[3, 15]`. Drives
  billing.
</ParamField>

<ParamField body="sound" type="boolean" default="false">
  Whether to synthesize an audio track. Flips the per-second rate from
  $0.399/s to $0.599/s.
</ParamField>

<ParamField body="cfg_scale" type="number" default="0.5">
  Classifier-free guidance strength. Range `[0, 1]`.
</ParamField>

<ParamField body="negative_prompt" type="string">
  Content to steer the model away from. Max 2500 characters.
</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": "kuaishou/kling-v3-4k-i2v",
    "prompt": "the subject turns toward the camera and smiles",
    "image_urls": ["https://example.com/portrait.jpg"],
    "duration": 5,
    "sound": true
  }'
```

```json theme={null}
{ "id": "kling_002…", "status": "pending", "model": "kuaishou/kling-v3-4k-i2v" }
```

Poll until terminal:

```bash theme={null}
curl https://routerbase.com/v1/videos/generations/kling_002… \
  -H "Authorization: Bearer $ROUTERBASE_API_KEY"
```

```json theme={null}
{
  "id": "kling_002…",
  "status": "success",
  "data": [{ "url": "https://…mp4" }]
}
```

## Reference