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

# Veo 3.1 Fast

> ### Veo 3.1 Fast

Cost-efficient Veo 3.1 tier that still delivers strong visual results. Generates from a text prompt, a single image, or first / last frames.

> For reference-image driven generation use `veo-3-1-fast-refs`. Sending `image_urls` / `ref_imgs` to this endpoint returns an error.

#### Pricing

Billed **per second** of output. Resolution changes the rate; 720p and 1080p are the same price.

| Resolution | Tokens / s | USD / s |
|---|---|---|
| 720p / 1080p | 8.06 | $0.1612 |
| 4k | 24.18 | $0.4836 |

1 token = $0.02.

Example: an 8s clip at 720p / 1080p costs 64.48 tokens.

#### Duration

**4**, **6** or **8** seconds. Billing is per second, so a shorter clip costs proportionally less.




## OpenAPI

````yaml api-reference/video-generations/openapi-veo-3-1-fast.json POST /api/v1/videos/generations
openapi: 3.1.0
info:
  title: GoEnhance API - Veo 3.1 Fast
  description: Video generation with Google Veo 3.1 Fast.
  version: 1.0.0
servers:
  - url: https://api.goenhance.ai
security: []
paths:
  /api/v1/videos/generations:
    post:
      tags:
        - VideoGenerations
      summary: Veo 3.1 Fast
      description: >
        ### Veo 3.1 Fast


        Cost-efficient Veo 3.1 tier that still delivers strong visual results.
        Generates from a text prompt, a single image, or first / last frames.


        > For reference-image driven generation use `veo-3-1-fast-refs`. Sending
        `image_urls` / `ref_imgs` to this endpoint returns an error.


        #### Pricing


        Billed **per second** of output. Resolution changes the rate; 720p and
        1080p are the same price.


        | Resolution | Tokens / s | USD / s |

        |---|---|---|

        | 720p / 1080p | 8.06 | $0.1612 |

        | 4k | 24.18 | $0.4836 |


        1 token = $0.02.


        Example: an 8s clip at 720p / 1080p costs 64.48 tokens.


        #### Duration


        **4**, **6** or **8** seconds. Billing is per second, so a shorter clip
        costs proportionally less.
      parameters:
        - name: Authorization
          in: header
          description: ''
          required: false
          example: '{{Authorization}}'
          schema:
            type: string
      requestBody:
        content:
          application/json:
            schema:
              type: object
              properties:
                model:
                  type: string
                  enum:
                    - veo-3-1-fast
                  description: Model name. Must be `veo3_1_fast`.
                  default: veo-3-1-fast
                prompt:
                  type: string
                  description: >-
                    Text prompt describing the video. Max 2000 tokens.
                    Translated to English automatically.
                image_url:
                  type: string
                  format: uri
                  description: >-
                    Optional. With only image_url the video unfolds from that
                    image; add image_end_url to generate a transition between
                    the two frames.
                image_end_url:
                  type: string
                  format: uri
                  description: >-
                    Optional. Last-frame image URL. Requires `image_url` —
                    last-frame-only is not supported.
                duration:
                  type: integer
                  enum:
                    - 4
                    - 6
                    - 8
                  default: 8
                  description: >-
                    Clip length in seconds. Billing is per video, so 4s and 8s
                    cost the same — 8 gives the most content for the price.
                quality:
                  type: string
                  enum:
                    - 720p
                    - 1080p
                    - 4k
                  default: 720p
                  description: >-
                    Output resolution. Changes the price — see the pricing table
                    above.
                ratio:
                  type: string
                  enum:
                    - '16:9'
                    - '9:16'
                    - Auto
                  default: '16:9'
                  description: >-
                    Output aspect ratio. `auto` lets the model pick from the
                    input image, or from the prompt for text-to-video. ⚠️ Fixed
                    at 16:9 when `ref_imgs` is used. `aspect_ratio` is accepted
                    as a compatible alias.
                custom_callback_url:
                  type: string
                  format: uri
                  description: >-
                    Optional. A publicly accessible HTTPS URL. When the task
                    status changes (processing / success / failed), GoEnhance
                    sends a POST request to this URL. The request body is
                    identical to the response of GET /api/v1/jobs/detail. If
                    your server does not respond with HTTP 200, the notification
                    is retried up to 3 times, with a 3-second timeout per
                    attempt.
                  example: https://your-server.com/goenhance/callback
              required:
                - model
                - prompt
            example:
              model: veo3_1_fast
              prompt: A cat playing piano in a jazz bar, cinematic
              duration: 6
              quality: 1080p
              ratio: '16:9'
              generate_audio: true
      responses:
        '200':
          description: ''
          content:
            application/json:
              schema:
                type: object
                properties:
                  code:
                    type: integer
                  msg:
                    type: string
                  data:
                    type: object
                    properties:
                      img_uuid:
                        type: string
                    required:
                      - img_uuid
                required:
                  - code
                  - msg
                  - data
              examples:
                '1':
                  summary: Success
                  value:
                    code: 0
                    msg: Success
                    data:
                      img_uuid: c12b656c-747a-44fd-9c80-add79b0c52d5
                '2':
                  summary: Insufficient tokens
                  value:
                    code: 100
                    msg: tokens is not enough
                quota:
                  summary: API key quota exceeded
                  value:
                    code: 101
                    msg: 'API key quota exceeded: 4990 of 5000 tokens used (monthly)'
          headers: {}
        '401':
          description: ''
          content:
            application/json:
              schema:
                type: object
                properties:
                  code:
                    type: integer
                  msg:
                    type: string
                required:
                  - code
                  - msg
          headers: {}
      deprecated: false

````