> ## Documentation Index > Fetch the complete documentation index at: https://docs.goenhance.ai/llms.txt > Use this file to discover all available pages before exploring further. # Kling 4.0 Flash Video Edit > Kling 4.0 Flash video edit. Change an existing clip of **3 to 20 seconds** with a prompt — swap outfits, restyle the scene, regrade the colors — optionally guided by up to **10 style reference images**. 720p only. The output keeps the aspect ratio and the original audio of your video. Refer to the source video in `prompt` as `<<>>` and to reference images as `<<>>`, `<<>>` … in the order of `image_urls`. **Pricing** — in tokens (USD at $0.02/token), billed on **output seconds + max(source video seconds, output seconds)**: | resolution | tokens/s | USD/s | |---|---|---| | 720p | 3.7143 | $0.074286 | The source video length is measured from your file before any tokens are charged, and rounded up to a whole second. With the default `duration: "auto"` the output is as long as the source, so a request is billed for twice the source length. Reference images are not charged. Examples: - 5-second source, `duration` auto: 10 billed seconds, 37.14 tokens (= $0.7428) - 10-second source, `duration` 20: 40 billed seconds, 148.57 tokens (= $2.9714) Returns an `img_uuid`; poll GET /api/v1/jobs/detail (or use `custom_callback_url`) to get the edited video. **Not accepted by this model** (rejected before any tokens are charged): source videos longer than 20 seconds (they are not trimmed), `ratio` / `aspect_ratio` (the output follows the source video), `sound` / `generate_audio` (the output always keeps the audio of your video), `negative_prompt`, `seed`, `image_url` / `image_end_url` / `keyframes`, and 1080p / 4K. ## OpenAPI ````yaml api-reference/video-generations/openapi-kling-4-0-flash-edit.json POST /api/v1/videos/generations openapi: 3.1.0 info: title: GoEnhance API - Kling 4.0 Flash Video Edit description: >- Video editing with Kling 4.0 Flash. Same endpoint as the other Kling models; the model is selected by model. version: 1.0.0 servers: - url: https://api.goenhance.ai security: [] paths: /api/v1/videos/generations: post: tags: - VideoGenerations summary: Kling 4.0 Flash Video Edit description: >- Kling 4.0 Flash video edit. Change an existing clip of **3 to 20 seconds** with a prompt — swap outfits, restyle the scene, regrade the colors — optionally guided by up to **10 style reference images**. 720p only. The output keeps the aspect ratio and the original audio of your video. Refer to the source video in `prompt` as `<<>>` and to reference images as `<<>>`, `<<>>` … in the order of `image_urls`. **Pricing** — in tokens (USD at $0.02/token), billed on **output seconds + max(source video seconds, output seconds)**: | resolution | tokens/s | USD/s | |---|---|---| | 720p | 3.7143 | $0.074286 | The source video length is measured from your file before any tokens are charged, and rounded up to a whole second. With the default `duration: "auto"` the output is as long as the source, so a request is billed for twice the source length. Reference images are not charged. Examples: - 5-second source, `duration` auto: 10 billed seconds, 37.14 tokens (= $0.7428) - 10-second source, `duration` 20: 40 billed seconds, 148.57 tokens (= $2.9714) Returns an `img_uuid`; poll GET /api/v1/jobs/detail (or use `custom_callback_url`) to get the edited video. **Not accepted by this model** (rejected before any tokens are charged): source videos longer than 20 seconds (they are not trimmed), `ratio` / `aspect_ratio` (the output follows the source video), `sound` / `generate_audio` (the output always keeps the audio of your video), `negative_prompt`, `seed`, `image_url` / `image_end_url` / `keyframes`, and 1080p / 4K. parameters: - name: Authorization in: header description: '' required: false example: '{{Authorization}}' schema: type: string requestBody: content: application/json: schema: type: object description: >- Kling 4.0 Flash video edit (one source video, optional style reference images). **Pricing** — per billed second (output + max(source, output)): - 720p — 3.7143 tokens ($0.074286) properties: model: type: string enum: - kling-4-0-flash-edit description: Model name. Must be `kling-4-0-flash-edit` on this page. prompt: type: string maxLength: 2500 description: >- Editing instructions. Required, up to 2500 characters. Refer to the source video as `<<>>` and to reference images as `<<>>` …; a number with no matching asset is rejected. video_urls: type: array minItems: 1 maxItems: 1 items: type: string format: uri description: >- The video to edit — exactly one URL. 3 to 20 seconds (longer videos are rejected, not trimmed). MP4 or MOV, up to 200MB, height 700-4553px. image_urls: type: array maxItems: 10 items: type: string format: uri description: >- Optional style reference image URLs (up to 10). `<<>>` is the first item. Up to 10MB each, width and height at least 300px, aspect ratio between 2:5 and 5:2. Smaller images are upscaled automatically. duration: oneOf: - type: integer minimum: 3 maximum: 20 - type: string enum: - auto default: auto description: >- Output duration: `"auto"` (default) matches the source video, or any integer from 3 to 20 seconds. Billing uses output + max(source, output) seconds. resolution: type: string enum: - 720p default: 720p description: >- Output resolution. Kling 4.0 Flash only supports 720p. `quality` is accepted as a compatible alias. custom_callback_url: type: string format: uri description: >- Optional. A publicly accessible HTTPS URL. When the task status changes (processing / success / failed), GoEnhance sends a POST request to this URL. The request body is identical to the response of GET /api/v1/jobs/detail. If your server does not respond with HTTP 200, the notification is retried up to 3 times, with a 3-second timeout per attempt. example: https://your-server.com/goenhance/callback required: - model - prompt - video_urls example: model: kling-4-0-flash-edit prompt: >- Replace the coat worn by the person in <<>> with the style in <<>> video_urls: - https://your-cdn.com/original.mp4 image_urls: - https://your-cdn.com/coat-style.jpg responses: '200': description: '' content: application/json: schema: type: object properties: code: type: integer msg: type: string data: type: object properties: img_uuid: type: string cost: type: number description: >- Tokens deducted for this request. This is the amount actually charged, so it already reflects any discount active on your account and can be lower than the listed price. Tokens are deducted when the task is accepted, and refunded automatically if the generation ends in failure. example: 5.82 required: - img_uuid - cost required: - code - msg - data examples: '1': summary: Success value: code: 0 msg: Success data: img_uuid: c12b656c-747a-44fd-9c80-add79b0c52d5 cost: 5.82 '2': summary: Insufficient tokens value: code: 100 msg: tokens is not enough quota: summary: API key quota exceeded value: code: 101 msg: 'API key quota exceeded: 4990 of 5000 tokens used (monthly)' headers: {} '401': description: '' content: application/json: schema: type: object properties: code: type: integer msg: type: string required: - code - msg examples: '1': summary: Unauthorized value: code: 401 msg: Unauthorized headers: {} deprecated: false security: [] ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.