> ## Documentation Index > Fetch the complete documentation index at: https://docs.vidgo.ai/llms.txt > Use this file to discover all available pages before exploring further. # Kling 2.1 Pro Image to Video > Kling 2.1 Pro image-to-video with a required start frame and an optional end frame. 1. Submit the request with `VIDGO_API_KEY`. A `task_id` is returned immediately. Keep it until the task reaches `finished` or `failed`. 2. Use [Query Task Status](/api-manual/task-management/status) to retrieve the result. If you provide a `callback_url`, Vidgo sends the result to your [webhook](/api-manual/task-management/webhooks) when the task finishes or fails. # Kling 2.1 Pro Image to Video Kling 2.1 Pro image-to-video with a required start frame and an optional end frame. ## Available Models * **kwaivgi/kling-video/v2.1/pro/image-to-video** - Generate video from image input. ## Duration Options * **5, 10 seconds** - Set `duration` as an integer. Optional. Default: **5 seconds** when omitted. Strings, booleans, null and fractional values are rejected. ## Key Features * Generate video from image input. * Use `start_image_url` to supply the starting frame. * Optionally supply an ending frame with `end_image_url`. ## Advanced Parameters Set `model` and optional `callback_url` at the request root. Place all workflow parameters, including output options, inside `input`. Send only the input fields supported by this workflow. Unsupported `input` fields are rejected before credits are deducted. Input URLs must use HTTP(S), include a hostname, and contain no embedded credentials. ### Prompt * `prompt`: Required. Describe the scene and desired motion. Length: **1-5,000 characters**. * The value must be a string and must not be blank after trimming. Non-string values are rejected. ### Start Image URL * `start_image_url`: Required. Provide the starting frame URL. Use a publicly accessible HTTP(S) URL without credentials or whitespace. Empty URLs and null are rejected. ### End Image URL * `end_image_url`: Optional. Provide the ending frame URL. Use a publicly accessible HTTP(S) URL without credentials or whitespace. Empty URLs and null are rejected. ### Negative Prompt * `negative_prompt`: Optional. Describe content to avoid. ## Billing Factors Billed per video according to the selected model tier (Standard or Pro) and video duration (`duration`). Credits are deducted on submission and refunded if the task fails. ## OpenAPI ````yaml api-manual/video-series/kwaivgi-kling-video-v2-1-pro-image-to-video.json POST /api/generate/submit openapi: 3.0.0 info: title: Vidgo API - Kling 2.1 Pro Image to Video description: >- Kling 2.1 Pro image-to-video with a required start frame and an optional end frame. version: 1.0.0 servers: - url: https://api.vidgo.ai security: - BearerAuth: [] paths: /api/generate/submit: post: tags: - Video Series summary: Kling 2.1 Pro Image to Video description: >- Kling 2.1 Pro image-to-video with a required start frame and an optional end frame. Unsupported input fields are rejected before credits are deducted. Billed per video according to the selected model tier (Standard or Pro) and video duration (`duration`). operationId: submit_kwaivgi_kling_video_v2_1_pro_image_to_video requestBody: required: true content: application/json: schema: type: object required: - model - input additionalProperties: true properties: model: type: string example: kwaivgi/kling-video/v2.1/pro/image-to-video input: type: object required: - prompt - start_image_url properties: prompt: type: string maxLength: 5000 minLength: 1 description: >- Required nonblank string, maximum 5,000 Unicode characters after trimming. duration: type: integer enum: - 5 - 10 default: 5 description: >- Optional integer: 5 or 10 seconds. Defaults to 5 when omitted. Strings, booleans, null and fractional durations are rejected. start_image_url: type: string format: uri description: >- Required first-frame public HTTP(S) URL, with a hostname and no credentials or whitespace. Empty URLs and null are rejected. end_image_url: type: string format: uri description: >- Optional last frame public HTTP(S) URL, with a hostname and no credentials or whitespace. Omit optional fields when unused; empty URLs and null are rejected. negative_prompt: type: string description: Negative prompt. additionalProperties: false callback_url: type: string nullable: true description: >- Optional public HTTP(S) endpoint for task completion notifications. HTTPS is recommended. Omit, use null, or use an empty string to disable callbacks. description: >- Keep model and callback_url at the root. Unknown root fields are ignored; unsupported input fields are rejected. examples: basic: summary: Basic workflow value: model: kwaivgi/kling-video/v2.1/pro/image-to-video input: prompt: >- A quiet forest under soft morning light, with natural detail. start_image_url: https://example.com/image.png duration: 5 callback: summary: Receive a completion callback value: model: kwaivgi/kling-video/v2.1/pro/image-to-video input: prompt: >- A quiet forest under soft morning light, with natural detail. start_image_url: https://example.com/image.png duration: 5 callback_url: https://your-domain.com/callback with_end_frame: summary: Pro with an optional end frame value: model: kwaivgi/kling-video/v2.1/pro/image-to-video input: prompt: >- A quiet forest under soft morning light, with natural detail. start_image_url: https://example.com/image.png duration: 5 end_image_url: https://example.com/end-frame.png responses: '200': description: Task submitted content: application/json: schema: type: object required: - code - data properties: code: type: integer enum: - 200 data: type: object required: - task_id - status - created_time properties: task_id: type: string status: type: string enum: - not_started - running - finished - failed created_time: type: string format: date-time example: code: 200 data: task_id: task-unified-example status: running created_time: '2026-09-10T08:00:00' '400': description: >- Invalid input, unsupported tier, inaccessible media, or insufficient credits content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '401': description: Invalid credentials content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '403': description: Access denied content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '404': description: Unknown or disabled model content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '408': description: Request timed out content: text/plain: schema: type: string example: Request timeout '422': description: Invalid JSON or non-object request body content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '429': description: Rate or API key credit limit exceeded content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '500': description: Internal error content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '502': description: Unable to create the upstream generation task content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} '503': description: Model configuration or capability is not approved content: application/json: schema: type: object required: - detail properties: detail: oneOf: - type: string - type: object additionalProperties: true - type: array items: {} components: securitySchemes: BearerAuth: type: http scheme: bearer description: Use VIDGO_API_KEY. ````