# Veo 3.1 Video Generation

> Generate videos with Veo 3.1 models through UniAll video APIs.

Canonical URL: https://docs.uniall.ai/models/video/veo-3-1
Locale: en

Veo 3.1 supports text-to-video, image-to-video, first-last-frame generation, multi-image reference generation, and video extension. Use the public model name to select the resolution and speed tier.

## Supported Models

| Model | Tier |
| --- | --- |
| `veo3.1-video-720p` | Standard 720p. |
| `veo3.1-video-1080p` | Standard 1080p. |
| `veo3.1-video-4k` | Standard 4K. |
| `veo3.1-fast-video-720p` | Fast 720p. |
| `veo3.1-fast-video-1080p` | Fast 1080p. |
| `veo3.1-fast-video-4k` | Fast 4K. |

## Endpoint

```http
POST /v1/video/generations
GET  /v1/videos/{task_id}
```

## Authentication

```http
Authorization: Bearer sk-***
Content-Type: application/json
```

## Request Parameters

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `model` | string | Yes | Veo 3.1 public model ID. |
| `prompt` | string | Strongly recommended | Main prompt. The schema is lenient, but production requests should include it. |
| `image` | string | Conditional | Single source image URL for image-to-video. |
| `images` | string[] | Conditional | `2` to `3` reference image URLs for multi-image reference generation. |
| `last_image` | string | Conditional | Target last-frame image URL; use with `image`. |
| `video` | string | Conditional | Source video URL for extension. |
| `size` | string | Recommended | Resolution hint, aligned to the selected model tier. |
| `aspect_ratio` | string | No | Text-to-video accepts `16:9` or `9:16`. Image-to-video and extension may not honor it. |
| `duration` | integer | Conditional | Output seconds. Allowed values: `4`, `6`, or `8`. Not used for video extension. |
| `extra_body.generate_audio` | boolean | No | Whether to generate audio; upstream usually defaults to `true`. |
| `extra_body.negative_prompt` | string | No | Content to avoid. |
| `extra_body.seed` | integer | No | Random seed for reproducibility. |

## Text-To-Video Example

```bash
curl -X POST "{BASE_URL}/v1/video/generations" \
  -H "Authorization: Bearer sk-***" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "veo3.1-video-1080p",
    "prompt": "A golden-hour street interview shot, slight handheld movement, natural city ambience, realistic human speech.",
    "size": "1080p",
    "aspect_ratio": "16:9",
    "duration": 8,
    "extra_body": {
      "generate_audio": true,
      "negative_prompt": "watermark, blur",
      "seed": 7
    }
  }'
```

## Image-To-Video Example

```bash
curl -X POST "{BASE_URL}/v1/video/generations" \
  -H "Authorization: Bearer sk-***" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "veo3.1-video-720p",
    "prompt": "A product slowly rotates on a clean studio desk with soft reflected light.",
    "image": "https://example.com/keyframe.png",
    "size": "720p",
    "aspect_ratio": "16:9",
    "duration": 6,
    "extra_body": {
      "generate_audio": false,
      "negative_prompt": "artifacts, camera shake"
    }
  }'
```

## First-Last-Frame Example

```bash
curl -X POST "{BASE_URL}/v1/video/generations" \
  -H "Authorization: Bearer sk-***" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "veo3.1-fast-video-1080p",
    "prompt": "Transition naturally from the first frame to the last frame, preserving subject identity and camera continuity.",
    "image": "https://example.com/start-frame.png",
    "last_image": "https://example.com/end-frame.png",
    "size": "1080p",
    "aspect_ratio": "16:9",
    "duration": 6
  }'
```

## Query Task Status

```bash
curl "{BASE_URL}/v1/videos/task_xxx" \
  -H "Authorization: Bearer sk-***"
```

```json
{
  "id": "task_xxx",
  "task_id": "task_xxx",
  "object": "video.generation.job",
  "model": "veo3.1-video-1080p",
  "status": "completed",
  "progress": 100,
  "video_url": "https://example.com/output.mp4"
}
```

## Billing Notes

Veo billing depends on model tier, speed tier, resolution, output duration, and audio generation. Use task settlement and current product pricing as the final source.

## Common Errors

- Passing `duration` outside `4`, `6`, or `8`.
- Mismatching `size` with the selected model tier.
- Expecting `aspect_ratio` to be honored for image-to-video or extension requests.
- Sending more than `3` reference images.
- Passing `video` without clarifying the extension use case in the prompt or extra body.

## Related Pages

- [Video Generation Overview](/models/video/overview)
- [Kling Video Generation](/models/video/kling)
- [Vidu Video Generation](/models/video/vidu)