Generate videos with Kling 4.0 Flash Reference 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/reference-to-video", {
input: {
prompt: "10-second macro product film for the fictional watchmaker AUREL, 16:9, black-velvet studio, one raking strip light. Four shots, hard cuts, slow and precise.
REFERENCES: @Image1 locks the dial (grand-feu white enamel, slim blued leaf hands, polished baton indices, small seconds at six, 'AUREL' under twelve). @Image2 locks the movement seen through the caseback. @Image3 locks the case flank, brushed and polished bevels and the fluted crown. @Image4 is the end card - reproduce it exactly.
0-3 s: @Image1. A motion-control slider glides slowly left to right across the dial at macro distance; the strip-light reflection travels across the domed sapphire; the blued small-seconds hand steps in fine six-beats-per-second increments.
3-6 s: @Image2. Slow push-in on the movement; the balance wheel oscillates steadily (about three swings per second), the hairspring breathing; light rakes across the Geneva stripes and blued screws.
6-8 s: @Image3. Locked-off extreme macro; the thin strip rim light travels slowly along the mirror-polished bevel and over the fluted crown, one bright glint running edge to edge across the dry steel.
8-10 s: hard cut as the glint leaves the crown to the end card of @Image4, held perfectly still; 'AUREL' and 'CALIBRE 7' pixel-identical.
AUDIO: close-mic mechanical ticking at six beats per second, crisp and dominant; a low warm analogue drone under it; a faint high metallic shimmer as the glint crosses the crown at about 7.8 s; one soft low piano note at 8 s that rings under the end card. No voice-over, no music beyond that note.
LOCKS: same case, dial, hands and indices across shots; no numerals appearing on the dial; no text except the dial print and the end card.
AVOID: any water, droplets, condensation or liquid anywhere, dial text drift or extra words, warped hands, hands moving at the wrong speed, a ticking quartz-style seconds jump on a sweep dial, lens flares, CG plastic look, fast cutting."
},
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/reference-to-video", {
input: {
prompt: "10-second macro product film for the fictional watchmaker AUREL, 16:9, black-velvet studio, one raking strip light. Four shots, hard cuts, slow and precise.
REFERENCES: @Image1 locks the dial (grand-feu white enamel, slim blued leaf hands, polished baton indices, small seconds at six, 'AUREL' under twelve). @Image2 locks the movement seen through the caseback. @Image3 locks the case flank, brushed and polished bevels and the fluted crown. @Image4 is the end card - reproduce it exactly.
0-3 s: @Image1. A motion-control slider glides slowly left to right across the dial at macro distance; the strip-light reflection travels across the domed sapphire; the blued small-seconds hand steps in fine six-beats-per-second increments.
3-6 s: @Image2. Slow push-in on the movement; the balance wheel oscillates steadily (about three swings per second), the hairspring breathing; light rakes across the Geneva stripes and blued screws.
6-8 s: @Image3. Locked-off extreme macro; the thin strip rim light travels slowly along the mirror-polished bevel and over the fluted crown, one bright glint running edge to edge across the dry steel.
8-10 s: hard cut as the glint leaves the crown to the end card of @Image4, held perfectly still; 'AUREL' and 'CALIBRE 7' pixel-identical.
AUDIO: close-mic mechanical ticking at six beats per second, crisp and dominant; a low warm analogue drone under it; a faint high metallic shimmer as the glint crosses the crown at about 7.8 s; one soft low piano note at 8 s that rings under the end card. No voice-over, no music beyond that note.
LOCKS: same case, dial, hands and indices across shots; no numerals appearing on the dial; no text except the dial print and the end card.
AVOID: any water, droplets, condensation or liquid anywhere, dial text drift or extra words, warped hands, hands moving at the wrong speed, a ticking quartz-style seconds jump on a sweep dial, lens flares, CG plastic look, fast cutting."
},
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/reference-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/reference-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 string* requiredText prompt. Reference inputs as @Image1, @Video1, @Element1, etc.
duration integerVideo duration in seconds (3-20). Default value: 5
start_image_url stringOptional image to use as the first frame. Counts toward the image reference limit.
Reference images, referenced as @Image1, @Image2, ... (max 10).
Reference videos (3-20s each, 20s combined with element videos), referenced as @Video1, @Video2, ... (max 5).
Characters/objects, referenced as @Element1, @Element2, ... (max 7). Up to 3 may be video elements. Flash does not accept voices.
resolution ResolutionEnumOutput resolution. Flash is 720p only. Default value: "720p"
Possible enum values: 720p
aspect_ratio AspectRatioEnumAspect ratio of the generated video. 'auto' adapts it to the references. Default value: "16:9"
Possible enum values: auto, 16:9, 9:16, 1:1, 21:9
{
"prompt": "10-second macro product film for the fictional watchmaker AUREL, 16:9, black-velvet studio, one raking strip light. Four shots, hard cuts, slow and precise.\nREFERENCES: @Image1 locks the dial (grand-feu white enamel, slim blued leaf hands, polished baton indices, small seconds at six, 'AUREL' under twelve). @Image2 locks the movement seen through the caseback. @Image3 locks the case flank, brushed and polished bevels and the fluted crown. @Image4 is the end card - reproduce it exactly.\n0-3 s: @Image1. A motion-control slider glides slowly left to right across the dial at macro distance; the strip-light reflection travels across the domed sapphire; the blued small-seconds hand steps in fine six-beats-per-second increments.\n3-6 s: @Image2. Slow push-in on the movement; the balance wheel oscillates steadily (about three swings per second), the hairspring breathing; light rakes across the Geneva stripes and blued screws.\n6-8 s: @Image3. Locked-off extreme macro; the thin strip rim light travels slowly along the mirror-polished bevel and over the fluted crown, one bright glint running edge to edge across the dry steel.\n8-10 s: hard cut as the glint leaves the crown to the end card of @Image4, held perfectly still; 'AUREL' and 'CALIBRE 7' pixel-identical.\nAUDIO: close-mic mechanical ticking at six beats per second, crisp and dominant; a low warm analogue drone under it; a faint high metallic shimmer as the glint crosses the crown at about 7.8 s; one soft low piano note at 8 s that rings under the end card. No voice-over, no music beyond that note.\nLOCKS: same case, dial, hands and indices across shots; no numerals appearing on the dial; no text except the dial print and the end card.\nAVOID: any water, droplets, condensation or liquid anywhere, dial text drift or extra words, warped hands, hands moving at the wrong speed, a ticking quartz-style seconds jump on a sweep dial, lens flares, CG plastic look, fast cutting.",
"duration": 10,
"image_urls": [
"https://v3b.fal.media/files/b/0aad8e7f/Rqg-pv2QnjyCj_qyhkb1L_image_1.png",
"https://v3b.fal.media/files/b/0aad8e7f/tZbpEZhQSFIdaP-4bA7mZ_image_2.png",
"https://v3b.fal.media/files/b/0aad90a6/fUtkQcN-M0lfbW0d64cgI_image_3.png",
"https://v3b.fal.media/files/b/0aad8e7f/-qNeGnjPP6Xv0L811MyJg_image_4.png"
],
"video_urls": null,
"elements": null,
"resolution": "720p",
"aspect_ratio": "16:9"
}The generated video.
{
"video": {
"url": "https://v3b.fal.media/files/b/0ab11f9f/7HQolYvL9QnowfKbZGQav_r2v.mp4",
"content_type": "video/mp4",
"file_size": 12186191,
"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.
frontal_image_url stringThe frontal image of the element (main view).
Additional views of the element from different angles (1-3).
video_url stringA video of the element, used instead of images (3-8s).