Kling 4.0 animates a starting image into a 3 to 30-second video at 720p or 1080p, with optional ending frames and per-shot prompts.
The client provides a convenient way to interact with the model API.
npm install --save @fal-ai/clientSet 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/image-to-video", {
input: {
start_image_url: "https://v3b.fal.media/files/b/rabbit/NaslJIC7F2WodS6DFZRRJ.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"
});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/image-to-video", {
input: {
start_image_url: "https://v3b.fal.media/files/b/rabbit/NaslJIC7F2WodS6DFZRRJ.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/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/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);Read more about file handling in our file upload guide.
prompt stringOptional text prompt. Leave empty (and omit multi_prompt) to animate the frames without one.
start_image_url string* requiredImage to use as the first frame of the video.
Max file size: 30.0MB, Min width: 300px, Min height: 300px, Min aspect ratio: 0.40, Max aspect ratio: 2.50, Timeout: 20.0s
Ordered keyframes between the first and last frames (max 8).
end_image_url stringImage to use as the last frame of the video.
Per-shot prompts for multi-shot generation. The video duration is the sum of the shot durations.
duration integerVideo duration in seconds (3-30). Default value: 5
resolution ResolutionEnumOutput resolution. Default value: "1080p"
Possible enum values: 720p, 1080p
{
"prompt": "A detective in a black trench coat stands on a rooftop in the rain, looking through a telescope at the street below.",
"start_image_url": "https://v3b.fal.media/files/b/rabbit/NaslJIC7F2WodS6DFZRRJ.png",
"middle_image_urls": null,
"end_image_url": "https://v3b.fal.media/files/b/tiger/BwHi22qoQnqaTNMMhe533.png",
"multi_prompt": null,
"duration": 5,
"resolution": "1080p"
}The generated video.
{
"video": {
"file_name": "output.mp4",
"content_type": "video/mp4",
"file_size": 2953131,
"url": "https://v3b.fal.media/files/b/0aac4496/HjUbnyfTPVcavQNpRh1QJ_clip_image.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.
prompt string* requiredThe prompt for this shot.
duration integerShot duration in seconds. Default value: 5