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

# Kling-4.0 Reference to Video

> - Kling-4.0 Reference to Video (kling-v4-reference-to-video) generates new videos from reference images and videos
- Reference videos provide feature references (not direct editing) and can be combined with text and reference images
- Asynchronous processing mode, use the returned task ID to [query status](/en/api-manual/task-management/get-task-detail)
- Generated video links are valid for 24 hours, please save them promptly



## OpenAPI

````yaml en/api-manual/video-series/kling/kling-v4-reference-to-video.json POST /v1/videos/generations
openapi: 3.1.0
info:
  title: kling-v4-reference-to-video API
  description: Create reference-to-video tasks using AI models
  license:
    name: MIT
  version: 1.0.0
servers:
  - url: https://api.evolink.ai
    description: Production
security:
  - bearerAuth: []
tags:
  - name: Video Generation
    description: AI video generation APIs
paths:
  /v1/videos/generations:
    post:
      tags:
        - Video Generation
      summary: kling-v4-reference-to-video API
      description: >-
        - Kling-4.0 Reference to Video (kling-v4-reference-to-video) generates
        new videos from reference images and videos

        - Reference videos provide feature references (not direct editing) and
        can be combined with text and reference images

        - Asynchronous processing mode, use the returned task ID to [query
        status](/en/api-manual/task-management/get-task-detail)

        - Generated video links are valid for 24 hours, please save them
        promptly
      operationId: createVideoGeneration
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/VideoGenerationRequest'
            examples:
              basic:
                summary: Basic Video Reference
                value:
                  model: kling-v4-reference-to-video
                  prompt: >-
                    Keep the same motion style as <<<video_1>>> and replace the
                    background with a snowy scene
                  video_urls:
                    - https://example.com/reference.mp4
                  duration: 5
                  aspect_ratio: '16:9'
                  quality: 720p
              pro:
                summary: High-quality portrait video
                value:
                  model: kling-v4-reference-to-video
                  prompt: >-
                    Generate a street dance video following the movement rhythm
                    in <<<video_1>>>
                  video_urls:
                    - https://example.com/dance.mp4
                  duration: 10
                  aspect_ratio: '9:16'
                  quality: 1080p
              with_reference_image:
                summary: Video and image references
                value:
                  model: kling-v4-reference-to-video
                  prompt: >-
                    The person from <<<image_1>>> walks through a scene in the
                    style of <<<video_1>>>
                  video_urls:
                    - https://example.com/reference.mp4
                  image_urls:
                    - https://example.com/character.jpg
                  duration: 8
                  quality: 1080p
              image_only:
                summary: Reference images only
                value:
                  model: kling-v4-reference-to-video
                  prompt: >-
                    The product from <<<image_1>>> sits on a wooden table as the
                    camera slowly circles it
                  image_urls:
                    - https://example.com/product.jpg
                  duration: 5
                  aspect_ratio: '1:1'
                  quality: 720p
      responses:
        '200':
          description: Video generation task created successfully
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/VideoGenerationResponse'
        '400':
          description: Invalid request parameters
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                error:
                  code: invalid_request
                  message: Invalid request parameters
                  type: invalid_request_error
        '401':
          description: Unauthenticated, token invalid or expired
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                error:
                  code: unauthorized
                  message: Invalid or expired token
                  type: authentication_error
        '402':
          description: Insufficient quota, top-up required
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                error:
                  code: insufficient_quota
                  message: Insufficient quota. Please top up your account.
                  type: insufficient_quota
        '403':
          description: Access denied
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                error:
                  code: model_access_denied
                  message: >-
                    Token does not have access to model:
                    kling-v4-reference-to-video
                  type: invalid_request_error
        '429':
          description: Rate limit exceeded
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                error:
                  code: rate_limit_exceeded
                  message: Too many requests, please try again later
                  type: rate_limit_error
        '500':
          description: Internal server error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
              example:
                error:
                  code: internal_error
                  message: Internal server error
                  type: api_error
components:
  schemas:
    VideoGenerationRequest:
      type: object
      required:
        - model
        - prompt
      properties:
        model:
          type: string
          description: Video generation model name
          enum:
            - kling-v4-reference-to-video
          default: kling-v4-reference-to-video
          example: kling-v4-reference-to-video
        prompt:
          type: string
          description: >-
            Text prompt, up to 2500 characters


            **Reference syntax:** Use `<<<xxx>>>` in the prompt to reference
            images and videos, for example: `The person from <<<image_1>>> walks
            down the street following the camera movement in <<<video_1>>>`
          example: >-
            The person from <<<image_1>>> walks down the street following the
            camera movement in <<<video_1>>>
          maxLength: 2500
        video_urls:
          type: array
          description: >-
            Reference video URL array, up to `5` clips, corresponding in order
            to `<<<video_1>>>`, `<<<video_2>>>`, etc. in the prompt


            **Video requirements:**

            - Formats: MP4 / MOV

            - Size: ≤ 200MB per clip

            - Duration: ≥ 3 seconds per clip, ≤ 30 seconds in total

            - Dimensions: width and height from 720px to 2160px

            - Frame rate: 24fps to 60fps

            - Video URLs must be directly accessible by the server
          items:
            type: string
            format: uri
          maxItems: 5
          example:
            - https://example.com/reference.mp4
        image_urls:
          type: array
          description: >-
            Reference image URL array (style, scene, or subject references),
            corresponding in order to `<<<image_1>>>`, `<<<image_2>>>`, etc. in
            the prompt


            **Constraints:** Up to `10` images

            **Note:** Image URLs must be directly accessible by the server or
            trigger a direct download when accessed
          items:
            type: string
            format: uri
          example:
            - https://example.com/character.jpg
          maxItems: 10
        duration:
          type: integer
          description: Video duration in seconds, from 3 to 30
          minimum: 3
          maximum: 30
          default: 5
          example: 5
        aspect_ratio:
          type: string
          description: |-
            Video aspect ratio

            **Options:**
            - `16:9`: Landscape
            - `9:16`: Portrait
            - `1:1`: Square
            - `21:9`: Ultrawide
          enum:
            - '16:9'
            - '9:16'
            - '1:1'
            - '21:9'
          example: '16:9'
          default: '16:9'
        quality:
          type: string
          description: |-
            Resolution tier

            **Options:**
            - `720p`: Standard 720P
            - `1080p`: High quality 1080P
          enum:
            - 720p
            - 1080p
          default: 720p
          example: 720p
        callback_url:
          type: string
          description: >-
            HTTPS callback URL for task completion


            **Callback Timing:**

            - Triggered when task is completed, failed, or cancelled

            - Sent after billing confirmation


            **Security Restrictions:**

            - HTTPS protocol only

            - Internal IP addresses are prohibited (127.0.0.1, 10.x.x.x,
            172.16-31.x.x, 192.168.x.x, etc.)

            - URL length must not exceed `2048` characters


            **Callback Mechanism:**

            - Timeout: `10` seconds

            - Maximum `3` retries after failure (at `1`/`2`/`4` seconds after
            failure)

            - Callback response format is consistent with task query API

            - 2xx status code is considered successful, other codes trigger
            retry
          format: uri
          example: https://your-domain.com/webhooks/video-task-completed
    VideoGenerationResponse:
      type: object
      properties:
        created:
          type: integer
          description: Task creation timestamp
          example: 1757169743
        id:
          type: string
          description: Task ID
          example: task-unified-1757169743-7cvnl5zw
        model:
          type: string
          description: Actual model name used
          example: kling-v4-reference-to-video
        object:
          type: string
          enum:
            - video.generation.task
          description: Task type
        progress:
          type: integer
          description: Task progress percentage (0-100)
          minimum: 0
          maximum: 100
          example: 0
        status:
          type: string
          description: Task status
          enum:
            - pending
            - processing
            - completed
            - failed
          example: pending
        task_info:
          $ref: '#/components/schemas/VideoTaskInfo'
          description: Video task details
        type:
          type: string
          enum:
            - text
            - image
            - audio
            - video
          description: Task output type
          example: video
        usage:
          $ref: '#/components/schemas/VideoUsage'
          description: Usage and billing information
    ErrorResponse:
      type: object
      properties:
        error:
          type: object
          properties:
            code:
              type: string
              description: Error code identifier
            message:
              type: string
              description: Error description
            type:
              type: string
              description: Error type
    VideoTaskInfo:
      type: object
      properties:
        can_cancel:
          type: boolean
          description: Whether the task can be cancelled
          example: true
        estimated_time:
          type: integer
          description: Estimated completion time (seconds)
          minimum: 0
          example: 300
        video_duration:
          type: integer
          description: Video duration (seconds)
          example: 9
    VideoUsage:
      type: object
      description: Usage and billing information
      properties:
        billing_rule:
          type: string
          description: Billing rule
          enum:
            - per_call
            - per_token
            - per_second
          example: per_second
        credits_reserved:
          type: number
          description: Estimated credits consumed
          minimum: 0
          example: 53.38
        user_group:
          type: string
          description: User group category
          example: default
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: >-
        ## All APIs require Bearer Token authentication ##


        **Get API Key:**


        Visit [API Key Management Page](https://evolink.ai/dashboard/keys) to
        get your API Key


        **Add to request header:**

        ```

        Authorization: Bearer YOUR_API_KEY

        ```

````

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