> ## 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.

# Kling V2.1 Master Image-to-Video

Kling 2.1 Master is the flagship version of the Kling 2.1 series, featuring top-tier image-to-video generation capabilities with exceptional motion smoothness, cinematic visual quality, outstanding prompt comprehension, and support for 1080p HD video output.

<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="image" type="string" required={true}>
  First frame image for the video. Supported image formats include `.jpg`, `.jpeg`, `.png`. Image file size must not exceed 10MB, with a minimum resolution of 300\*300 pixels.
</ParamField>

<ParamField body="prompt" type="string" required={true}>
  Positive prompt text for video generation. Must not exceed 2500 characters.
</ParamField>

<ParamField body="duration" type="string" default="5">
  Duration of the generated video (in seconds).

  Possible values: `5`, `10`
</ParamField>

<ParamField body="guidance_scale" type="number" default={0.5}>
  Guidance scale parameter that controls how closely the generated content adheres to the prompt.

  Range: 0 to 1<br />
  Step: 0.01
</ParamField>

<ParamField body="negative_prompt" type="string">
  Negative prompt to specify content to avoid in the generation. Must not exceed 2500 characters.
</ParamField>

## Response

<ResponseField name="task_id" type="string" required={true}>
  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.
</ResponseField>