POST
/
api
/
v1
/
mj
/
generateVideoExtend
Extend Midjourney Video
curl --request POST \
  --url https://api.kie.ai/api/v1/mj/generateVideoExtend \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "prompt": "Continue the scene with the spacecraft accelerating into a colorful nebula with dynamic light trails",
  "taskType": "mj_video_extend_manual",
  "taskId": "ee603959-debb-48d1-98c4-a6d1c717eba6",
  "index": 0,
  "waterMark": "my_watermark",
  "callBackUrl": "https://api.example.com/callback"
}'
{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "40d90dd1c6fddsa0a7dssa2a08366149"
  }
}

​
Usage Guide

  • Provide the original video taskId and index to continue from the generated result
  • Choose between manual extension (with prompt) or automatic extension
  • Use prompt to guide how the video should continue while keeping consistency
  • Optional callback is supported

​
Parameter Details

  • prompt required for manual extension, describes what should happen next
  • taskType extension mode: mj_video_extend_manual or mj_video_extend_auto
  • taskId identifies the original MJ video record to extend
  • index video index from the original record to extend
  • callBackUrl callback URL for receiving completion updates
  • waterMark video watermark, optional

​
Developer Notes

  • Extended videos are stored for 15 days before automatic deletion
  • Extension maintains the same aspect ratio and style as the original video
  • Manual extension requires a prompt, automatic extension uses AI-generated continuation

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
​
taskType
enum<string>
required

Extension type for video generation mode.

  • mj_video_extend_manual: Manual extension with custom prompt
  • mj_video_extend_auto: Automatic extension using AI-generated continuation
Available options:
mj_video_extend_manual,
mj_video_extend_auto
Example:

"mj_video_extend_manual"

​
taskId
string
required

Task ID of the original MJ video record to extend

Example:

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

​
index
integer
required

Video index from the original record to extend

Example:

0

​
prompt
string

Continuation prompt describing what should happen next in the video. Required for manual extension. Max length: 2000 characters

Example:

"Continue the scene with the spacecraft accelerating into a colorful nebula with dynamic light trails"

​
waterMark
string

Video watermark, optional

Example:

"my_watermark"

​
callBackUrl
string<uri>

Callback URL to receive extension completion updates. Optional but recommended in production.

  • System will POST task status and results to this URL upon completion
  • Alternatively, use the Get Midjourney Task Details endpoint to poll status

📖 Detailed callback format: See Midjourney Video Extension Callbacks

Example:

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

Response

Request successful

​
code
enum<integer>

Response status code

  • 200: Success - Request has been processed successfully
  • 400: Bad Request - Invalid request parameters
  • 401: Unauthorized - Authentication credentials are missing or invalid
  • 402: Insufficient Credits - Account does not have enough credits to perform the operation
  • 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
  • 455: Service Unavailable - System is currently undergoing maintenance
  • 500: Server Error - An unexpected error occurred while processing the request
  • 501: Generation Failed - Video extension task failed
  • 505: Feature Disabled - The requested feature is currently disabled
Available options:
200,
400,
401,
402,
404,
422,
429,
455,
500,
501,
505
​
msg
string

Response message

Example:

"success"

​
data
object