Generate videos with Kling 4.0 Flash Image to Video
The client provides a convenient way to interact with the model API.
npm install --save @fal-ai/clientThe @fal-ai/serverless-client package has been deprecated in favor of @fal-ai/client. Install the new package and update your imports — see client setup.
Set FAL_KEY as an environment variable in your runtime.
export FAL_KEY="YOUR_API_KEY"The client API handles the API submit protocol. It will handle the request status updates and return the result when the request is completed.
import { fal } from "@fal-ai/client";
const result = await fal.subscribe("kling/v4/flash/image-to-video", {
input: {
start_image_url: "https://v3b.fal.media/files/b/0aad8e98/IExjfxS5kaUm5jnqK5yfB_image_1.png"
},
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);The API uses an API Key for authentication. It is recommended you set the FAL_KEY environment variable in your runtime when possible.
import { fal } from "@fal-ai/client";
fal.config({
credentials: "YOUR_FAL_KEY"
});When running code on the client-side (e.g. in a browser, mobile app or GUI applications), make sure to not expose your FAL_KEY. Instead, use a server-side proxy to make requests to the API. For more information, check out our server-side integration guide.
The client API provides a convenient way to submit requests to the model.
import { fal } from "@fal-ai/client";
const { request_id } = await fal.queue.submit("kling/v4/flash/image-to-video", {
input: {
start_image_url: "https://v3b.fal.media/files/b/0aad8e98/IExjfxS5kaUm5jnqK5yfB_image_1.png"
},
webhookUrl: "https://optional.webhook.url/for/results",
});You can fetch the status of a request to check if it is completed or still in progress.
import { fal } from "@fal-ai/client";
const status = await fal.queue.status("kling/v4/flash/image-to-video", {
requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b",
logs: true,
});Once the request is completed, you can fetch the result. See the Output Schema for the expected result format.
import { fal } from "@fal-ai/client";
const result = await fal.queue.result("kling/v4/flash/image-to-video", {
requestId: "764cabcf-b745-4b3e-ae38-1200304cf45b"
});
console.log(result.data);
console.log(result.requestId);Some attributes in the API accept file URLs as input. Whenever that's the case you can pass your own URL or a Base64 data URI.
You can pass a Base64 data URI as a file input. The API will handle the file decoding for you. Keep in mind that for large files, this alternative although convenient can impact the request performance.
You can also pass your own URLs as long as they are publicly accessible. Be aware that some hosts might block cross-site requests, rate-limit, or consider the request as a bot.
We provide a convenient file storage that allows you to upload files and use them in your requests. You can upload files using the client API and use the returned URL in your requests.
import { fal } from "@fal-ai/client";
const file = new File(["Hello, World!"], "hello.txt", { type: "text/plain" });
const url = await fal.storage.upload(file);The client will auto-upload the file for you if you pass a binary object (e.g. File, Data).
Read more about file handling in our file upload guide.
prompt stringOptional text prompt describing the shot.
start_image_url string* requiredImage to use as the first frame of the video. Flash does not take an end frame.
Max file size: 30.0MB, Min width: 300px, Min height: 300px, Min aspect ratio: 0.40, Max aspect ratio: 2.50, Timeout: 20.0s
duration integerVideo duration in seconds (3-20). Default value: 5
resolution ResolutionEnumOutput resolution. Flash is 720p only. Default value: "720p"
Possible enum values: 720p
{
"prompt": "The same elements in the reference are rigid: the fictional KITO Runner 01 low-top sneaker: off-white suede overlays (#EEE9DF) on a bone-coloured finely perforated engineered mesh upper, a sage-green suede heel tab (#8FA383), a natural gum-rubber cupsole with a fine herringbone edge, tonal off-white flat laces and tonal off-white stitching; the only marking is a small debossed \"KITO\" on the sage heel tab. It is a single right shoe standing on a warm light-grey paper seamless that curves up into the background with no visible horizon line. Preserve every element exactly; the shoe and the set are frozen, only the camera moves along the keyframed trajectory: one complete, eased 360-degree orbit around the shoe like a motion-control product rig, dipping slightly lower as it passes the back and the inner side, then rising and pushing in gently to finish on a slightly higher hero three-quarter view of the same outer side it started on.\nUNSEEN SIDES must be coherent with the visible ones: the heel shows the full sage-green suede heel tab with the small debossed 'KITO' centred on it; the medial (inner) side mirrors the lateral side's off-white suede overlay layout on the perforated bone mesh; the gum cupsole wraps all the way round with the same height and herringbone edge; tonal off-white laces and stitching everywhere. The shoe is one pair-half: never a second shoe.\nLIGHT is fixed in the world: one large soft key from the upper left, so as the camera orbits the suede nap and perforations catch raking light on the far side and the gum sole glows slightly translucent when backlit; the soft contact shadow stays anchored to the floor.\nAVOID: the shoe rotating or sliding instead of the camera, sole thickness changing, extra eyelets, lace geometry re-tying itself, stripes or swoosh-like marks appearing, logo text anywhere except the heel tab, seamless edge or studio gear coming into frame, flicker, warped toe box.",
"start_image_url": "https://v3b.fal.media/files/b/0aad8e98/IExjfxS5kaUm5jnqK5yfB_image_1.png",
"duration": 10,
"resolution": "720p"
}The generated video.
{
"video": {
"url": "https://v3b.fal.media/files/b/0ab11f9e/u_FE9bAbOG_cCzLBiqCN2_i2v.mp4",
"content_type": "video/mp4",
"file_size": 16480268,
"file_name": "output.mp4"
}
}url string* requiredThe URL where the file can be downloaded from.
content_type stringThe mime type of the file.
file_name stringThe name of the file. It will be auto-generated if not provided.
file_size integerThe size of the file in bytes.