Kling Video O1 Image To Video API

API reference for Kling Video O1 Image To Video. Generate a video by taking a start frame and an end frame, animating the transition between them while following text-driven style and scene guidance.

Endpoint: POST https://fal.run/fal-ai/kling-video/o1/image-to-video Endpoint ID: fal-ai/kling-video/o1/image-to-video

Try it in the Playground

Run this model interactively with your own prompts.

Quick Start

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(
    "fal-ai/kling-video/o1/image-to-video",
    arguments={
        "prompt": "Create a magical timelapse transition. The snow melts rapidly to reveal green grass, and the tree branches burst into bloom with pink flowers in real-time. The lighting shifts from cold winter light to warm spring sunshine. The camera pushes in slowly towards the tree. Disney-style magical transformation, cinematic, 8k.",
        "start_image_url": "https://v3b.fal.media/files/b/rabbit/NaslJIC7F2WodS6DFZRRJ.png"
    },
    with_logs=True,
    on_queue_update=on_queue_update,
)
print(result)

import { fal } from "@fal-ai/client";

const result = await fal.subscribe("fal-ai/kling-video/o1/image-to-video", {
  input: {
      prompt: "Create a magical timelapse transition. The snow melts rapidly to reveal green grass, and the tree branches burst into bloom with pink flowers in real-time. The lighting shifts from cold winter light to warm spring sunshine. The camera pushes in slowly towards the tree. Disney-style magical transformation, cinematic, 8k.",
      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);

curl --request POST \
  --url https://fal.run/fal-ai/kling-video/o1/image-to-video \
  --header "Authorization: Key $FAL_KEY" \
  --header "Content-Type: application/json" \
  --data '{
  "prompt": "Create a magical timelapse transition. The snow melts rapidly to reveal green grass, and the tree branches burst into bloom with pink flowers in real-time. The lighting shifts from cold winter light to warm spring sunshine. The camera pushes in slowly towards the tree. Disney-style magical transformation, cinematic, 8k.",
  "start_image_url": "https://v3b.fal.media/files/b/rabbit/NaslJIC7F2WodS6DFZRRJ.png"
}'

Kuaishou’s Kling O1 delivers first-frame-last-frame video generation at $0.112 per second, animating precise transitions between two keyframes. Trading broad creative freedom for exact endpoint control, this specialized variant handles timelapse transformations, morphing sequences, and narrative scene transitions where both start and end states matter. Built for motion designers, creative studios, and developers who need deterministic video outputs rather than open-ended generation.

Built for: Timelapse animations | Product transformation sequences | Narrative scene transitions

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Dual-Keyframe Control Architecture

Kling O1’s dual-keyframe approach inverts the standard image-to-video workflow by accepting both start and end images as constraints, then synthesizing the motion path between them. Where traditional image-to-video models extrapolate freely from a single frame, this variant interpolates along a defined trajectory while respecting prompt-driven style guidance.

What this means for you:

• Deterministic endpoints: Generate 5 or 10-second videos where both opening and closing frames match your exact specifications, critical for brand-consistent sequences or narrative continuity
• Controlled transformation arcs: Animate seasonal changes, product evolutions, or character state transitions with predictable motion paths rather than AI-improvised endings
• Prompt-guided interpolation: Reference start and end frames via @Image1 and @Image2 in prompts to direct style, camera movement, and scene dynamics during the transition
• Flexible duration options: Choose between 5-second ($0.56) or 10-second ($1.12) outputs to match pacing requirements for social media clips or longer editorial sequences

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Performance Scaling

Kling O1 operates within Kuaishou’s broader Kling Video ecosystem, prioritizing frame-accurate transitions over generation speed.

Metric	Result	Context
Duration Options	5s or 10s	Configurable via duration parameter
Cost per Video	$0.56 (5s) or$1.12 (10s)	Based on $0.112 per second rate
Input Requirements	Start + end frame (both required)	Min 300px dimensions, 0.40-2.50 aspect ratio, 10MB max per image
Output Format	MP4 video	Single video file with synthesized motion path

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Technical Specifications

Spec	Details
Architecture	Kling O1
Input Formats	Start image (required), end image (required), text prompt with frame references
Output Formats	MP4 video
Duration Options	5 seconds or 10 seconds
Prompt Syntax	Use @Image1 and @Image2 to reference uploaded keyframes in prompts
License	Commercial use via fal partnership

API Documentation

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How It Stacks Up

Kling Video Image to Video (v2.5-turbo) - Kling O1 specializes in dual-keyframe interpolation for transformation sequences where endpoint precision matters, making it ideal for timelapse effects and morphing animations. Kling Video v2.5-turbo emphasizes single-frame extrapolation with faster generation speeds for open-ended creative exploration.

Kling 2.0 Master Image to Video - Kling O1 trades generation flexibility for endpoint accuracy, constraining motion paths between two defined frames at a specialized price point. Kling 2.0 Master prioritizes maximum quality single-frame animation for premium production workflows requiring cinematic motion without endpoint constraints.

Related

• Kling O1 Edit Video [Pro] — Video Generation
• Kling O1 First Frame Last Frame to Video [Standard] — Video Generation
• Kling O1 Reference Image to Video [Pro] — Video Generation
• Kling O1 Reference Video to Video [Pro] — Video Generation

Capabilities

• Text prompt input
• Duration control

API Reference

Input Schema

prompt · string · required

Use @Image1 to reference the start frame, @Image2 to reference the end frame.

start_image_url · string · required

Image to use as the first frame of the video.

Max file size: 10.0MB, Min width: 300px, Min height: 300px, Min aspect ratio: 0.40, Max aspect ratio: 2.50, Timeout: 20.0s

end_image_url · string

Image to use as the last frame of the video.

duration · DurationEnum · default: "5"

Video duration in seconds. Default value: "5"

Possible values: 3, 4, 5, 6, 7, 8, 9, 10

Output Schema

video · File · required

The generated video.

Input Example

{
  "prompt": "Create a magical timelapse transition. The snow melts rapidly to reveal green grass, and the tree branches burst into bloom with pink flowers in real-time. The lighting shifts from cold winter light to warm spring sunshine. The camera pushes in slowly towards the tree. Disney-style magical transformation, cinematic, 8k.",
  "start_image_url": "https://v3b.fal.media/files/b/rabbit/NaslJIC7F2WodS6DFZRRJ.png",
  "end_image_url": "https://v3b.fal.media/files/b/tiger/BwHi22qoQnqaTNMMhe533.png",
  "duration": "5"
}

Output Example

{
  "video": {
    "content_type": "video/mp4",
    "file_name": "output.mp4",
    "file_size": 27588984,
    "url": "https://v3b.fal.media/files/b/koala/knryyyGF3ZVyMMrGr77CL_output.mp4"
  }
}

Limitations

• duration restricted to: 3, 4, 5, 6, 7, 8, 9, 10