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

# Veo 3.1 Video Generation (Reverse)

Video generation and query API

<Tip>
  This is an **async** API that only returns the task\_id of the async task. Use the task\_id to call the [Get Async Task Result API](/docs/models/reference-get-async-task-result) to retrieve the generated result.
</Tip>

## Request Headers

<ParamField header="Content-Type" type="string" required={true}>
  Enum: `application/json`
</ParamField>

<ParamField header="Authorization" type="string" required={true}>
  Bearer authentication format: Bearer \{\{API Key}}.
</ParamField>

## Request Body

<ParamField body="size" type="string">
  Width x Height. Exact values are ignored; width > height produces landscape orientation, width \< height produces portrait orientation. Supported values: 1280x720, 720x1280.
</ParamField>

<ParamField body="prompt" type="string" required={true}>
  Text prompt to guide video generation. Example: Characters in the image start racing and then collide with each other.
</ParamField>

<ParamField body="seconds" type="integer">
  Video duration. Currently only 8 seconds is supported.
</ParamField>

<ParamField body="watermark" type="boolean">
  Whether to add a watermark. Default: no watermark.
</ParamField>

<ParamField body="input_images" type="array">
  Image files to guide video generation. veo-3.1-reverse supports uploading first frame and last frame images.
</ParamField>

## Response

<ResponseField name="task_id" type="string" required={true}>
  Use the task\_id to call the [Get Async Task Result API](/docs/models/reference-get-async-task-result) to retrieve the generated output.
</ResponseField>