Kling 4.0 Flash Image To Video API

kwaivgi/kling-v4.0-flash/image-to-video

Kling V4.0 Flash Image-to-Video animates a first-frame image into high-quality videos with synchronized audio, focusing on fast generation and rapid iteration for image animation, social content, marketing videos, storytelling, and production workflows. Ready-to-use REST inference API.

Image to Video
Input

Drag & drop or click to upload

preview

Idle

$0.094per run·~10 / $1

ExamplesView all

Use the woman, wolf, and moonlit forest from <Image 1>. Preserve her exact face, hairstyle, armor, pose, and environment. The white wolf suddenly lifts its head and growls softly. She immediately turns and raises her bow halfway. Something unseen moves in the darkness ahead. The camera arcs slightly around her, keeping both her and the wolf in frame. Dark fantasy tension, clear motion, cinematic atmosphere.

Related Models

README

Kling V4.0 Flash Image-to-Video

Kling V4.0 Flash Image-to-Video animates a first-frame image into a 720p video with synchronized audio. Flash is the fast, lower-cost tier of Kling 4.0: 720p clips of 3 to 20 seconds with synchronized audio, for quick iteration and volume work.

Why Choose This?

  • Keep your composition — The video starts from your image.
  • Fast iteration — Try several motions for the same frame quickly.
  • Up to 20 seconds — Any length from 3 to 20 seconds.
  • Native audio — Sound is generated together with the picture.

Parameters

ParameterRequiredDescription
imageYesFirst frame image (.jpg / .jpeg / .png).
promptNoDescribe the motion, camera and sound.
durationNo3 to 20 seconds, default 5.
aspect_ratioNo16:9, 9:16, 1:1 or 21:9. Leave it out to follow the image.

Pricing

$0.094 per second of output at 720p (a 5 second clip costs $0.47).

Notes

  • Flash takes a first frame only; for a last frame or middle keyframes use Kling V4.0 Image-to-Video.

Related Models

Note:This website uses AI models provided by third parties. Documentation prices are for reference and may be outdated. The Generate button shows an estimate; the final task charge prevails.

Kling v4.0 Flash Image To Video API — Quick start

Grab a WaveSpeedAI API key, then call POST https://api.wavespeed.ai/api/v3/kwaivgi/kling-v4.0-flash/image-to-video with your input as JSON. The endpoint returns a prediction id. Start polling the result endpoint around every 2 seconds, increase the interval for long-running tasks, and stop on any terminal status. On completed, read output values from data.outputs. Examples for Kling v4.0 Flash Image To Video below.

HTTP example
set -euo pipefail

: "${WAVESPEED_API_KEY:?Set WAVESPEED_API_KEY}"

REQUEST_BODY=$(cat <<'JSON'
{
    "image": "https://interactive-examples.mdn.mozilla.net/media/cc0-images/painted-hand-298-332.jpg",
    "duration": 5,
    "aspect_ratio": "16:9"
}
JSON
)

# 1. Submit the prediction.
SUBMIT_RESPONSE=$(curl --silent --show-error --fail-with-body \
  -X POST "https://api.wavespeed.ai/api/v3/kwaivgi/kling-v4.0-flash/image-to-video" \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $WAVESPEED_API_KEY" \
  -d "$REQUEST_BODY")

TASK=$(printf '%s' "$SUBMIT_RESPONSE" | jq 'if has("data") then .data else . end')
PREDICTION_ID=$(printf '%s' "$TASK" | jq -r '.id')
if [ -z "$PREDICTION_ID" ] || [ "$PREDICTION_ID" = "null" ]; then
  printf 'Submission response did not contain a prediction id
' >&2
  exit 1
fi
RESULT_URL="https://api.wavespeed.ai/api/v3/predictions/$PREDICTION_ID/result"

# 2. Poll until the prediction finishes.
while true; do
  RESPONSE=$(curl --silent --show-error --fail-with-body "$RESULT_URL" \
    -H "Authorization: Bearer $WAVESPEED_API_KEY")
  RESULT=$(printf '%s' "$RESPONSE" | jq 'if has("data") then .data else . end')
  STATUS=$(printf '%s' "$RESULT" | jq -r '.status')
  case "$STATUS" in
    completed) printf '%s\n' "$RESULT" | jq '.outputs'; break ;;
    failed|cancelled|timeout|deleted) printf '%s\n' "$RESULT" | jq . >&2; exit 1 ;;
    *) sleep 2 ;;
  esac
done
Node.js example
const submitUrl = "https://api.wavespeed.ai/api/v3/kwaivgi/kling-v4.0-flash/image-to-video";
const apiKey = process.env.WAVESPEED_API_KEY;
if (!apiKey) throw new Error('Set WAVESPEED_API_KEY');

async function requestJson(url, options = {}) {
  const response = await fetch(url, options);
  if (!response.ok) throw new Error(await response.text());
  return response.json();
}

// 1. Submit the prediction.
const body = await requestJson(submitUrl, {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${apiKey}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
        "image": "https://interactive-examples.mdn.mozilla.net/media/cc0-images/painted-hand-298-332.jpg",
        "duration": 5,
        "aspect_ratio": "16:9"
}),
});
const task = body.data ?? body;
if (!task.id) throw new Error("Submission response did not contain a prediction id");
const resultUrl = `https://api.wavespeed.ai/api/v3/predictions/${task.id}/result`;

// 2. Poll until the prediction finishes.
while (true) {
  const resultBody = await requestJson(resultUrl, {
    headers: { "Authorization": `Bearer ${apiKey}` },
  });
  const result = resultBody.data ?? resultBody;
  if (result.status === "completed") {
    console.log(result.outputs);
    break;
  }
  if (["failed", "cancelled", "timeout", "deleted"].includes(result.status)) throw new Error(JSON.stringify(result));
  await new Promise(resolve => setTimeout(resolve, 2000));
}
Python example
import json
import os
import time
from urllib.request import Request, urlopen

api_key = os.environ["WAVESPEED_API_KEY"]
headers = {"Authorization": f"Bearer {api_key}", "Content-Type": "application/json"}
payload = {
    "image": "https://interactive-examples.mdn.mozilla.net/media/cc0-images/painted-hand-298-332.jpg",
    "duration": 5,
    "aspect_ratio": "16:9"
}

def request_json(url, data=None):
    request = Request(url, data=data, headers=headers, method="POST" if data else "GET")
    with urlopen(request) as response:
        return json.load(response)

# 1. Submit the prediction.
body = request_json("https://api.wavespeed.ai/api/v3/kwaivgi/kling-v4.0-flash/image-to-video", json.dumps(payload).encode())
task = body.get("data", body)
if not task.get("id"):
    raise RuntimeError("Submission response did not contain a prediction id")
result_url = f"https://api.wavespeed.ai/api/v3/predictions/{task['id']}/result"

# 2. Poll until the prediction finishes.
while True:
    result_body = request_json(result_url)
    result = result_body.get("data", result_body)
    status = result.get("status")
    if status == "completed":
        print(result.get("outputs", []))
        break
    if status in {"failed", "cancelled", "timeout", "deleted"}:
        raise RuntimeError(result)
    time.sleep(2)

Kling v4.0 Flash Image To Video API — Frequently asked questions

What is the Kling v4.0 Flash Image To Video API?

Kling v4.0 Flash Image To Video is a Kuaishou model for video generation from images, exposed as a REST API on WaveSpeedAI. Kling V4.0 Flash Image-to-Video animates a first-frame image into high-quality videos with synchronized audio, focusing on fast generation and rapid iteration for image animation, social content, marketing videos, storytelling, and production workflows. Ready-to-use REST inference API. You can call it programmatically or try it from the playground above.

How do I call the Kling v4.0 Flash Image To Video API?

POST your input parameters to the model's REST endpoint (shown in the API tab of this playground) with your WaveSpeedAI API key in the Authorization header. Submission returns a prediction ID. Poll the result endpoint starting around every 2 seconds, increase the interval for long-running tasks, and stop on any terminal status. The playground generates Python, JavaScript, and cURL examples for submitting requests and polling results. Full request/response shape is documented at https://wavespeed.ai/docs/docs-api/kwaivgi/kwaivgi-kling-v4.0-flash-image-to-video.

How much does Kling v4.0 Flash Image To Video cost per run or per second?

Kling v4.0 Flash Image To Video starts at $0.094 per run or per second. That figure is the base price — the final charge scales with the parameters you set in the form (output size, length, count, references, or whatever knobs this model exposes), so a higher-quality or larger output costs more than a minimal one. The exact cost for your current input is shown live next to the Generate button before you submit, and the actual per-call charge is recorded on the prediction afterwards.

What inputs does Kling v4.0 Flash Image To Video accept?

Key inputs: `prompt`, `image`, `aspect_ratio`, `duration`. The full JSON schema (types, defaults, allowed values) is rendered above the Generate button and mirrored in the API reference at https://wavespeed.ai/docs/docs-api/kwaivgi/kwaivgi-kling-v4.0-flash-image-to-video.

How do I get started with the Kling v4.0 Flash Image To Video API?

Sign up for a free WaveSpeedAI account to claim starter credits, copy your API key from /accesskey, then call the endpoint shown in the API tab of the playground. The playground also auto-generates a code sample in Python, JavaScript, or cURL for the parameters you've set.

Can I use Kling v4.0 Flash Image To Video outputs commercially?

Commercial usage rights depend on the model's license, set by its provider (Kuaishou). Check the provider's applicable terms and WaveSpeedAI's Terms of Service before commercial use.

llms.txt — kwaivgi/kling-v4.0-flash/image-to-video for AI agents and LLMs