# Kling 4.0 Flash Video Editing > Kling 4.0 Flash edits an input video using text instructions and optional image, video or element references, producing 3 to 20-second videos at 720p. ## Overview - **Endpoint**: `https://fal.run/kling/v4/flash/video-to-video` - **Model ID**: `kling/v4/flash/video-to-video` - **Category**: video-to-video - **Kind**: inference **Tags**: kling, v4, flash, video-to-video, video-editing ## Pricing Video costs **$0.063** per second at **720p**, billed on the output duration plus the greater of the input video duration and the output duration. For more details, see [fal.ai pricing](https://fal.ai/pricing). ## API Information This model can be used via our HTTP API or more conveniently via our client libraries. See the input and output schema below, as well as the usage examples. ### Input Schema The API accepts the following input parameters: - **`prompt`** (`string`, _required_): Edit instruction. Reference the source video as @Video1. - Examples: "The blocky car proxy is the KESSEL R4 rally car from @Image1 - chalk-white body with the diagonal signal-orange and charcoal band, black 27 on a white roundel on the doors, slim LED headlamps joined by a light bar, roof scoop, rear wing, red mudflaps, white six-spoke gravel wheels. The grey road ribbon is the loose ochre-grey gravel stage and the cones and cylinders are the pine and birch forest of @Image2, on a crisp autumn morning with low sun raking through the trees and hanging dust. The mannequin proxies behind the rope are rally spectators in muted outdoor jackets and beanies behind red-and-white tape. Keep the exact blocking, timing, camera position and pan of the playblast. Physically real gravel rally: the car slides through the hairpin with opposite lock, rear wheels throwing a thick fan of gravel and a rolling dust cloud that drifts across the spectators; stones rattle off the bank; the suspension works over the ruts; spectators flinch, cheer and raise phones. Sound: a turbocharged four-cylinder rally engine on anti-lag with pops and bangs, gravel spray, crowd cheering. No text other than the number 27, no sponsor logos." - **`video_url`** (`string`, _required_): The video to edit (3-20s), referenced as @Video1. Max file size: 300.0MB, Min width: 700px, Min height: 700px, Max width: 4553px, Max height: 4553px, Min aspect ratio: 0.40, Max aspect ratio: 2.50, Min duration: 3.0s, Max duration: 20.05s, Min FPS: 23.9, Max FPS: 60.05, Timeout: 30.0s - Examples: "https://v3b.fal.media/files/b/0aad8e8d/Nig30TEV-F60iywH0q2z6_source_video.mp4" - **`image_urls`** (`list`, _optional_): Reference images, referenced as @Image1, @Image2, ... (max 10). - Array of string - Examples: ["https://v3b.fal.media/files/b/0aad8e8d/cWf3NfeTaRd6UzjMUpBDV_image_1.png","https://v3b.fal.media/files/b/0aad8e8d/Lf2iDZzwyoaqzTBkzg7OB_image_2.png"] - **`video_urls`** (`list`, _optional_): Reference videos, referenced as @Video2, @Video3, ... (max 4). The source, reference and element videos must total at most 20s. - Array of string - Examples: null - **`elements`** (`list`, _optional_): Characters/objects, referenced as @Element1, @Element2, ... (max 7). Up to 3 may be video elements. Flash does not accept voices. - Array of KlingV4FlashElement - Examples: null - **`duration`** (`integer`, _optional_): Output duration in seconds (3-20). Defaults to the source video's length. - Range: `3` to `20` - Examples: 8 - **`resolution`** (`ResolutionEnum`, _optional_): Output resolution. Flash is 720p only. Default value: `"720p"` - Default: `"720p"` - Options: `"720p"` **Required Parameters Example**: ```json { "prompt": "The blocky car proxy is the KESSEL R4 rally car from @Image1 - chalk-white body with the diagonal signal-orange and charcoal band, black 27 on a white roundel on the doors, slim LED headlamps joined by a light bar, roof scoop, rear wing, red mudflaps, white six-spoke gravel wheels. The grey road ribbon is the loose ochre-grey gravel stage and the cones and cylinders are the pine and birch forest of @Image2, on a crisp autumn morning with low sun raking through the trees and hanging dust. The mannequin proxies behind the rope are rally spectators in muted outdoor jackets and beanies behind red-and-white tape. Keep the exact blocking, timing, camera position and pan of the playblast. Physically real gravel rally: the car slides through the hairpin with opposite lock, rear wheels throwing a thick fan of gravel and a rolling dust cloud that drifts across the spectators; stones rattle off the bank; the suspension works over the ruts; spectators flinch, cheer and raise phones. Sound: a turbocharged four-cylinder rally engine on anti-lag with pops and bangs, gravel spray, crowd cheering. No text other than the number 27, no sponsor logos.", "video_url": "https://v3b.fal.media/files/b/0aad8e8d/Nig30TEV-F60iywH0q2z6_source_video.mp4" } ``` **Full Example**: ```json { "prompt": "The blocky car proxy is the KESSEL R4 rally car from @Image1 - chalk-white body with the diagonal signal-orange and charcoal band, black 27 on a white roundel on the doors, slim LED headlamps joined by a light bar, roof scoop, rear wing, red mudflaps, white six-spoke gravel wheels. The grey road ribbon is the loose ochre-grey gravel stage and the cones and cylinders are the pine and birch forest of @Image2, on a crisp autumn morning with low sun raking through the trees and hanging dust. The mannequin proxies behind the rope are rally spectators in muted outdoor jackets and beanies behind red-and-white tape. Keep the exact blocking, timing, camera position and pan of the playblast. Physically real gravel rally: the car slides through the hairpin with opposite lock, rear wheels throwing a thick fan of gravel and a rolling dust cloud that drifts across the spectators; stones rattle off the bank; the suspension works over the ruts; spectators flinch, cheer and raise phones. Sound: a turbocharged four-cylinder rally engine on anti-lag with pops and bangs, gravel spray, crowd cheering. No text other than the number 27, no sponsor logos.", "video_url": "https://v3b.fal.media/files/b/0aad8e8d/Nig30TEV-F60iywH0q2z6_source_video.mp4", "image_urls": [ "https://v3b.fal.media/files/b/0aad8e8d/cWf3NfeTaRd6UzjMUpBDV_image_1.png", "https://v3b.fal.media/files/b/0aad8e8d/Lf2iDZzwyoaqzTBkzg7OB_image_2.png" ], "video_urls": null, "elements": null, "duration": 8, "resolution": "720p" } ``` ### Output Schema The API returns the following output format: - **`video`** (`File`, _required_): The generated video. - Examples: {"url":"https://v3b.fal.media/files/b/0ab1204d/IVTSiS7Vp0-ChChUzFh12_output.mp4","content_type":"video/mp4","file_size":18009112,"file_name":"output.mp4"} **Example Response**: ```json { "video": { "url": "https://v3b.fal.media/files/b/0ab1204d/IVTSiS7Vp0-ChChUzFh12_output.mp4", "content_type": "video/mp4", "file_size": 18009112, "file_name": "output.mp4" } } ``` ## Usage Examples ### cURL ```bash curl --request POST \ --url https://fal.run/kling/v4/flash/video-to-video \ --header "Authorization: Key $FAL_KEY" \ --header "Content-Type: application/json" \ --data '{ "prompt": "The blocky car proxy is the KESSEL R4 rally car from @Image1 - chalk-white body with the diagonal signal-orange and charcoal band, black 27 on a white roundel on the doors, slim LED headlamps joined by a light bar, roof scoop, rear wing, red mudflaps, white six-spoke gravel wheels. The grey road ribbon is the loose ochre-grey gravel stage and the cones and cylinders are the pine and birch forest of @Image2, on a crisp autumn morning with low sun raking through the trees and hanging dust. The mannequin proxies behind the rope are rally spectators in muted outdoor jackets and beanies behind red-and-white tape. Keep the exact blocking, timing, camera position and pan of the playblast. Physically real gravel rally: the car slides through the hairpin with opposite lock, rear wheels throwing a thick fan of gravel and a rolling dust cloud that drifts across the spectators; stones rattle off the bank; the suspension works over the ruts; spectators flinch, cheer and raise phones. Sound: a turbocharged four-cylinder rally engine on anti-lag with pops and bangs, gravel spray, crowd cheering. No text other than the number 27, no sponsor logos.", "video_url": "https://v3b.fal.media/files/b/0aad8e8d/Nig30TEV-F60iywH0q2z6_source_video.mp4" }' ``` ### Python Ensure you have the Python client installed: ```bash pip install fal-client ``` Then use the API client to make requests: ```python import fal_client def on_queue_update(update): if isinstance(update, fal_client.InProgress): for log in update.logs: print(log["message"]) result = fal_client.subscribe( "kling/v4/flash/video-to-video", arguments={ "prompt": "The blocky car proxy is the KESSEL R4 rally car from @Image1 - chalk-white body with the diagonal signal-orange and charcoal band, black 27 on a white roundel on the doors, slim LED headlamps joined by a light bar, roof scoop, rear wing, red mudflaps, white six-spoke gravel wheels. The grey road ribbon is the loose ochre-grey gravel stage and the cones and cylinders are the pine and birch forest of @Image2, on a crisp autumn morning with low sun raking through the trees and hanging dust. The mannequin proxies behind the rope are rally spectators in muted outdoor jackets and beanies behind red-and-white tape. Keep the exact blocking, timing, camera position and pan of the playblast. Physically real gravel rally: the car slides through the hairpin with opposite lock, rear wheels throwing a thick fan of gravel and a rolling dust cloud that drifts across the spectators; stones rattle off the bank; the suspension works over the ruts; spectators flinch, cheer and raise phones. Sound: a turbocharged four-cylinder rally engine on anti-lag with pops and bangs, gravel spray, crowd cheering. No text other than the number 27, no sponsor logos.", "video_url": "https://v3b.fal.media/files/b/0aad8e8d/Nig30TEV-F60iywH0q2z6_source_video.mp4" }, with_logs=True, on_queue_update=on_queue_update, ) print(result) ``` ### JavaScript Ensure you have the JavaScript client installed: ```bash npm install --save @fal-ai/client ``` Then use the API client to make requests: ```javascript import { fal } from "@fal-ai/client"; const result = await fal.subscribe("kling/v4/flash/video-to-video", { input: { prompt: "The blocky car proxy is the KESSEL R4 rally car from @Image1 - chalk-white body with the diagonal signal-orange and charcoal band, black 27 on a white roundel on the doors, slim LED headlamps joined by a light bar, roof scoop, rear wing, red mudflaps, white six-spoke gravel wheels. The grey road ribbon is the loose ochre-grey gravel stage and the cones and cylinders are the pine and birch forest of @Image2, on a crisp autumn morning with low sun raking through the trees and hanging dust. The mannequin proxies behind the rope are rally spectators in muted outdoor jackets and beanies behind red-and-white tape. Keep the exact blocking, timing, camera position and pan of the playblast. Physically real gravel rally: the car slides through the hairpin with opposite lock, rear wheels throwing a thick fan of gravel and a rolling dust cloud that drifts across the spectators; stones rattle off the bank; the suspension works over the ruts; spectators flinch, cheer and raise phones. Sound: a turbocharged four-cylinder rally engine on anti-lag with pops and bangs, gravel spray, crowd cheering. No text other than the number 27, no sponsor logos.", video_url: "https://v3b.fal.media/files/b/0aad8e8d/Nig30TEV-F60iywH0q2z6_source_video.mp4" }, logs: true, onQueueUpdate: (update) => { if (update.status === "IN_PROGRESS") { update.logs.map((log) => log.message).forEach(console.log); } }, }); console.log(result.data); console.log(result.requestId); ``` ## Deploy your own model To run your own weights, a fine-tune or a custom pipeline on the GPUs that serve this API, deploy it on fal Serverless. GPUs from H100 (80GB) to B300 (288GB), billed per second; an H100 is $4.50/h list, as low as $2.49/h. Prices, GPU specs and deploy steps: [fal Serverless](https://fal.ai/serverless.md). ## Additional Resources ### Documentation - [Model Playground](https://fal.ai/models/kling/v4/flash/video-to-video) - [API Documentation](https://fal.ai/models/kling/v4/flash/video-to-video/api) - [OpenAPI Schema](https://fal.ai/api/openapi/queue/openapi.json?endpoint_id=kling/v4/flash/video-to-video) ### fal.ai Platform - [Platform Documentation](https://fal.ai/docs/documentation) - [Python Client](https://fal.ai/docs/api-reference/client-libraries/python) - [JavaScript Client](https://fal.ai/docs/api-reference/client-libraries/javascript) ### Other agent-readable surfaces This file covers one model. To find anything else: - [Platform overview](https://fal.ai/llms.txt): Entry points and representative endpoint IDs - [Documentation index](https://fal.ai/docs/llms.txt): Every documentation page - [Full documentation text](https://fal.ai/docs/llms-full.txt): The whole documentation inlined - [Pricing](https://fal.ai/pricing.md): Model API and Serverless GPU prices - [fal Serverless](https://fal.ai/serverless.md): Deploy your own models: GPU prices, specs and steps - Any other model: `https://fal.ai/models//llms.txt`