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POST
/
api
/
v1
/
runway
/
extend
Extend AI Video
curl --request POST \
  --url https://api.kie.ai/api/v1/runway/extend \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "taskId": "ee603959-debb-48d1-98c4-a6d1c717eba6",
  "prompt": "The cat continues dancing with more energy and excitement, spinning around with colorful light effects intensifying",
  "imageUrl": "https://file.com/m/xxxxxxxx.png",
  "expandPrompt": true,
  "waterMark": "kie.ai",
  "callBackUrl": "https://api.example.com/callback"
}'
{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "ee603959-debb-48d1-98c4-a6d1c717eba6"
  }
}

​
Usage Guide

  • Add additional segments to your AI-generated videos
  • Maintain visual consistency while extending narratives
  • Create longer sequences for storytelling or demonstrations

​
Parameter Details

  • taskId identifies the original video to extend
  • prompt guides how the video should continue
  • quality video resolution, optional values are 720p or 1080p.
  • waterMark video watermark text content, empty string means no watermark

​
Developer Notes

  • Extended videos are stored for 14 days before automatic deletion
  • Extension maintains the same aspect ratio as the original video
  • Extension works best when continuing the same subject/theme as the original video

Authorizations

​
Authorization
string
header
required

All APIs require authentication via Bearer Token.

Get API Key:

  1. Visit API Key Management Page to get your API Key

Usage: Add to request header: Authorization: Bearer YOUR_API_KEY

Note:

  • Keep your API Key secure and do not share it with others
  • If you suspect your API Key has been compromised, reset it immediately in the management page

Body

application/json
​
taskId
string
required

Unique identifier of the original video generation task. Must be a valid task ID from a previously generated video.

Example:

"ee603959-debb-48d1-98c4-a6d1c717eba6"

​
prompt
string
required

Descriptive text that guides the continuation of the video. Explain what actions, movements, or developments should happen next. Be specific but maintain consistency with the original video content.

Example:

"The cat continues dancing with more energy and excitement, spinning around with colorful light effects intensifying"

​
quality
string
required

Video resolution, optional values are 720p or 1080p.

Example:

"720p"

​
waterMark
string

Video watermark text content. An empty string indicates no watermark, while a non-empty string will display the specified text as a watermark in the bottom right corner of the video.

Example:

"kie.ai"

​
callBackUrl
string

The URL to receive AI video extension task completion updates. Required for all video extension requests.

  • System will POST task status and results to this URL when video extension completes
  • Callback includes extended video URLs, cover images, and task information
  • Your callback endpoint should accept POST requests with JSON payload containing extension results
  • For detailed callback format and implementation guide, see Video Extension Callbacks
  • Alternatively, use the Get AI Video Details endpoint to poll task status
Example:

"https://api.example.com/callback"

Response

Request successful

​
code
enum<integer>

Response status code

  • 200: Success - Request has been processed successfully
  • 401: Unauthorized - Authentication credentials are missing or invalid
  • 404: Not Found - The requested resource or endpoint does not exist
  • 422: Validation Error - The request parameters failed validation checks.The request parameters are incorrect, please check the parameters.
  • 429: Rate Limited - Request limit has been exceeded for this resource
  • 451: Unauthorized - Failed to fetch the image. Kindly verify any access limits set by you or your service provider.
  • 455: Service Unavailable - System is currently undergoing maintenance
  • 500: Server Error - An unexpected error occurred while processing the request
Available options:
200,
401,
404,
422,
429,
451,
455,
500
​
msg
string

Status message

Example:

"success"

​
data
object
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