Kling Video Extend

Extend existing videos to generate longer duration video content.

1. Create Task

Endpoint: POST /kling/v1/videos/video-extend

Description: Submit a video extend task. Video extension is an asynchronous process. After successful submission, a task_id will be returned. You need to query the result through the query endpoint.

Authentication: Bearer Token

Authorization: Bearer YOUR_API_TOKEN

Request Parameters (Body)

Field	Type	Required	Default	Description
video_id	string	Required	-	Video ID, the original video ID to be extended
prompt	string	Optional	empty	Positive text prompt to guide the video extension direction. Max 2500 characters.
negative_prompt	string	Optional	empty	Negative text prompt to exclude unwanted content. Max 2500 characters.
cfg_scale	number	Optional	0.5	Prompt reference strength, range [0, 1]. Higher values make generated content closer to the prompt.
callback_url	string	Optional	-	Callback URL for task result notification.

Response Parameters

Field	Type	Description
code	integer	Error code (0 indicates success)
message	string	Error message
request_id	string	Request ID
data	object	Data object
data.task_id	string	Task ID
data.task_status	string	Task status: submitted, processing, succeed, failed

Request Example

{
  "video_id": "vid_original_123456",
  "prompt": "Continue showing the beautiful sunset, slowly zooming out",
  "negative_prompt": "blurry, shaky",
  "cfg_scale": 0.5
}

---

2. Query Task

Endpoint: GET /kling/v1/videos/video-extend/:task_id

Description: Query the status and result of a video extend task by task ID.

Authentication: Bearer Token

Authorization: Bearer YOUR_API_TOKEN

Path Parameters

Field	Type	Required	Description
task_id	string	Required	Task ID returned by the create task endpoint

Response Parameters

Field	Type	Description
code	integer	Error code (0 indicates success)
message	string	Error message
request_id	string	Request ID for tracking and debugging
data	object	Data object
data.task_id	string	Task ID
data.task_status	string	Task status: submitted, processing, succeed, failed
data.task_status_msg	string	Task status message, shows failure reason when task fails
data.task_result	object	Task result (only returned on success)
data.task_result.videos	array	Generated video list
data.task_result.videos[].id	string	Generated video ID, globally unique
data.task_result.videos[].url	string	Generated video URL (Note: videos will be cleaned up after 30 days, please save them in time)
data.task_result.videos[].duration	string	Video duration in seconds
data.created_at	integer	Task creation time, Unix timestamp (ms)
data.updated_at	integer	Task update time, Unix timestamp (ms)

Response Example

{
  "code": 0,
  "message": "success",
  "request_id": "req_123456",
  "data": {
    "task_id": "task_123456",
    "task_status": "succeed",
    "task_status_msg": "success",
    "task_result": {
      "videos": [
        {
          "id": "vid_extended_123",
          "url": "https://example.com/extended_video.mp4",
          "duration": "10"
        }
      ]
    },
    "created_at": 1722769557708,
    "updated_at": 1722769557708
  }
}