> ## Documentation Index > Fetch the complete documentation index at: https://docs.poyo.ai/llms.txt > Use this file to discover all available pages before exploring further. # Kling 4.0 > Generate 3–30 second videos from text, reference images, and reference videos at 720p or 1080p. > [!TIP] > > 1. After submission, a `task_id` will be returned. If you provided a `callback_url`, when the task status becomes `finished` or `failed`, a POST request will be sent to the `callback_url`. > 2. Regardless of whether `callback_url` is provided, you can retrieve the response result through the unified [Query Task Status](/api-manual/task-management/status.md) endpoint. Kling 4.0 creates videos from a text prompt and optional visual references. Combine reference images and reference videos to guide appearance, movement, and scene composition. ## Models * **kling-4.0** — Text and reference-guided video generation ## Features * **Flexible duration**: Generate 3–30 second videos at `720p` or `1080p`. * **Visual references**: Supply up to 10 reference images and up to 5 reference videos. Refer to them in the prompt as `@image_1` and `@video_1`, using their positions in the corresponding arrays. * **Aspect ratios**: Use `auto`, `16:9`, `9:16`, `1:1`, or `21:9`. ## Required parameters * `prompt` (string): Video instructions, 1–8,000 characters. Must contain at least one non-whitespace character. Reference uploaded materials with `@image_1` or `@video_1`. ## Optional parameters * `duration` (integer): Output duration from 3 to 30 seconds. Default: `5`. * `resolution` (string): `720p` or `1080p`. Default: `720p`. * `aspect_ratio` (string): `auto`, `16:9`, `9:16`, `1:1`, or `21:9`. When omitted, the ratio adapts to supplied materials; without materials, it defaults to `16:9`. * `reference_image_urls` (array of strings): Up to 10 publicly accessible HTTP or HTTPS image URLs. * `reference_video_urls` (array of strings): Up to 5 publicly accessible HTTP or HTTPS video URLs. Each video must last 3–30 seconds. ## Examples * **Text-to-video**: Send a `prompt` without reference materials. Set `duration`, `resolution`, or `aspect_ratio` only when needed. * **Reference images**: Supply `reference_image_urls` and refer to the first image as `@image_1`. * **Reference videos**: Supply `reference_video_urls` and use `@video_1` to refer to the first video. The request examples in the API playground demonstrate these inputs. ## Notes * Provide at most 10 reference images and at most 5 reference videos. The combined duration of all reference videos cannot exceed 30 seconds. * Reference indexes start at 1 and follow the order of the corresponding input array. Use publicly accessible media URLs and omit unused optional fields. ## OpenAPI ````yaml api-manual/video-series/kling-4-0.json POST /api/generate/submit openapi: 3.0.0 info: title: Kling 4.0 description: Generate videos from text, reference images, and reference videos. version: 1.0.0 servers: - url: https://api.poyo.ai security: - BearerAuth: [] paths: /api/generate/submit: post: summary: Submit a Kling 4.0 video task operationId: submit_kling_4_0 requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/SubmitRequest' examples: text-to-video: summary: Generate video from a text prompt value: model: kling-4.0 input: prompt: A paper boat floats through a miniature city at sunset. reference-image: summary: Guide the video with a reference image value: model: kling-4.0 input: prompt: >- The character in @image_1 walks along a sunlit forest trail. reference_image_urls: - https://example.com/character.png duration: 10 resolution: 1080p aspect_ratio: '16:9' reference-video: summary: Guide movement with a reference video value: model: kling-4.0 input: prompt: >- Recreate the camera movement from @video_1 in a snowy mountain landscape. reference_video_urls: - https://example.com/camera-motion.mp4 duration: 10 responses: '200': description: Task submitted successfully content: application/json: schema: $ref: '#/components/schemas/SubmitResponse' '400': description: Invalid request parameters content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '401': description: Unauthorized - Invalid API key content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' components: schemas: SubmitRequest: type: object additionalProperties: false required: - model - input properties: model: type: string enum: - kling-4.0 description: Public model identifier. callback_url: type: string format: uri description: Optional webhook URL for task completion or failure notifications. input: type: object additionalProperties: false required: - prompt description: >- Text instructions with up to 10 reference images and up to 5 reference videos. The combined duration of all reference videos must not exceed 30 seconds. properties: prompt: type: string minLength: 1 maxLength: 8000 description: >- Video instructions. Must contain at least one non-whitespace character. Use @image_1 and @video_1 to reference the first item in the corresponding reference array. Reference indexes start at 1. duration: type: integer minimum: 3 maximum: 30 default: 5 description: Output duration in whole seconds. resolution: type: string enum: - 720p - 1080p default: 720p description: Output video resolution. aspect_ratio: type: string enum: - auto - '16:9' - '9:16' - '1:1' - '21:9' description: >- Output aspect ratio. When omitted, adapts to supplied materials; without materials, defaults to 16:9. reference_image_urls: type: array maxItems: 10 items: type: string format: uri description: >- Up to 10 publicly accessible HTTP or HTTPS reference image URLs. Reference them as @image_1, @image_2, and so on, in array order. reference_video_urls: type: array maxItems: 5 x-video-duration-seconds: minimum: 3 maximum: 30 items: type: string format: uri description: >- Publicly accessible HTTP or HTTPS reference videos, each lasting 3-30 seconds. Reference them as @video_1, @video_2, and so on, in array order. Provide at most 5 videos with a combined duration of at most 30 seconds. SubmitResponse: type: object required: - code - data properties: code: type: integer example: 200 data: type: object required: - task_id - status - created_time properties: task_id: type: string example: task-unified-1792741800-example status: type: string enum: - not_started example: not_started created_time: type: string format: date-time example: '2026-10-23T10:30:00' ErrorResponse: type: object required: - code - error properties: code: type: integer example: 400 error: type: object required: - message - type properties: message: type: string example: Invalid request parameters type: type: string example: invalid_request_error securitySchemes: BearerAuth: type: http scheme: bearer bearerFormat: API Key ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.