These three models belong to the same Veo 3.1 family and share an identical request structure. You can switch between veo-3.1-generate-001, veo-3.1-fast-generate-001, and veo-3.1-lite by changing only the model field. The differences are: Veo 3.1 and Veo 3.1 Fast support resolutions up to 4K (2160p), while Veo 3.1 Lite supports up to 1080p; and the guidances.image_reference parameter is available only on veo-3.1-generate-001.

Sample Request

curl --request POST \
     --url https://cloud.leonardo.ai/api/rest/v2/generations \
     --header 'accept: application/json' \
     --header 'authorization: Bearer <YOUR_API_KEY>' \
     --header 'content-type: application/json' \
     --data '
{
    "model": "veo-3.1-generate-001",
    "public": false,
    "parameters": {
      "prompt": "<YOUR_PROMPT>",
      "guidances": {
        "start_frame": [
          {
            "image": {
              "id": "<YOUR_START_IMAGE_ID>",
              "type": "UPLOADED"
            }
          }
        ],
        "end_frame": [
          {
            "image": {
              "id": "<YOUR_END_IMAGE_ID>",
              "type": "UPLOADED"
            }
          }
        ]
      },
      "duration": 8,
      "motion_has_audio": true,
      "quantity": 1,
      "width": 1280,
      "height": 720
    }
}
'

API Request Endpoint, Headers, Parameters

Endpoint

https://cloud.leonardo.ai/api/rest/v2/generations

Headers

--header "accept: application/json" \
--header "authorization: Bearer <YOUR_API_KEY>" \
--header "content-type: application/json"

Body Parameters

Parameter	Type	Definition
duration	`integer`	Length of the generated video in seconds. Set to `4`, `6`, or `8`. Defaults to `8`.
guidances.end_frame	`array`	Maximum 1 item. Each item includes image.id and image.type (`GENERATED` or `UPLOADED`). Only available when `start_frame` is provided.
guidances.image_reference	`array`	Reference images to guide your video generation. Maximum 3 items. Each item includes image.id, image.type, and strength (`LOW`, `MID`, `HIGH`; defaults to `MID`). Available only on `veo-3.1-generate-001`.
guidances.start_frame	`array`	Maximum 1 item. Each item includes image.id and image.type (`GENERATED` or `UPLOADED`).
height	`integer`	Sets the height of the output video in pixels. See the Dimensions table for accepted values.
model	`string`	Specifies the model used for generation. Set to `veo-3.1-generate-001`, `veo-3.1-fast-generate-001`, or `veo-3.1-lite`. These three models are interchangeable and accept the same request structure.
motion_has_audio	`boolean`	Whether the video generation will include audio. Valid values are `true` and `false`. Defaults to `true`.
negative_prompt	`string`	The negative prompt to use for the generation. Maximum of 1000 characters.
prompt	`string`	Text description of the video content to generate. Maximum of 9999 characters.
public	`boolean`	Controls whether the generated video is public (true) or private (false).
quantity	`integer`	The number of outputs to generate. Must be `1`. Defaults to `1`.
seed	`number`	The seed value for generation. Accepts a value from `0` to `4294967295`.
width	`integer`	Sets the width of the output video in pixels. See the Dimensions table for accepted values.

Dimensions

The API accepts width and height parameters in the following aspect ratio combinations:

Resolution	Aspect Ratio	Pixel Values (Width x Height)
720p	16:9 (Landscape)	1280x720
	9:16 (Portrait)	720x1280
1080p	16:9 (Landscape)	1920x1080
	9:16 (Portrait)	1080x1920
2160p / 4K (not supported on Veo 3.1 Lite)	16:9 (Landscape)	3840x2160
	9:16 (Portrait)	2160x3840