Extend Video

Extend video duration with new frames

POST /v1/extend-video

Extend Video

cURL

curl --request POST \
  --url https://api.legnext.ai/api/v1/extend-video \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "jobId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "videoNo": 1,
  "prompt": "<string>",
  "callback": "<string>"
}
'

400

{
  "code": 400,
  "message": "Invalid request parameters",
  "raw_message": "Invalid request parameters",
  "detail": null
}

Each extension adds 4 seconds to the video duration, with a maximum of 4 extensions (creating up to 21-second videos).

Headers

Header	Type	Required	Description
x-api-key	string	Yes	Your API key

Request Body

Parameter	Type	Required	Description
jobId	string	Yes	ID of the original video generation task
videoNo	integer	Yes	Video number to extend (0/1/2/3)
prompt	string	No	Text prompt to guide the extension (1-8192 characters)
callback	string	No	Callback URL for task completion notifications

Example Request

cURL

curl -X POST "https://api.legnext.ai/api/v1/extend-video" \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "jobId": "b24ffa07-7b76-49a2-963e-f6c527f7cec7",
    "videoNo": 0,
    "prompt": "Continue with more dynamic movement and effects",
    "callback": "https://webhook.site/c98cb890-fb92-439f-8d60-42c8a51eb52d"
  }'

Response

Returns a task object containing the task information.

{
    "job_id": "e41e5586-dcee-4659-ae56-dbf19d20051a",
    "model": "midjourney",
    "task_type": "extend_video",
    "status": "pending",
    "config": {
        "service_mode": "public",
        "webhook_config": {
            "endpoint": "https://webhook.site/xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
            "secret": ""
        }
    },
    "input": null,
    "output": {
        "video_urls": null,
        "seed": ""
    },
    "meta": {
        "created_at": "",
        "started_at": "",
        "ended_at": "",
        "usage": {
            "type": "point",
            "frozen": 480,
            "consume": 0
        }
    },
    "detail": null,
    "logs": [],
    "error": {
        "code": 0,
        "raw_message": "",
        "message": "",
        "detail": null
    }
}

This is the initial success response. Use the job_id to check the task status via the Get Task endpoint to retrieve the completed result with video URLs.

Authorizations

x-api-key · string · header · required

API key for authentication

Body

application/json

jobId · string<uuid> · required

ID of the original video task

videoNo · integer · required

Video number to extend (0/1/2/3)

Required range: 0 <= x <= 3

prompt · string

Text prompt to guide the extension

Required string length: 1 - 8192

callback · string<uri>

Callback URL for task completion notifications

Response

200

application/json

Video extend task created successfully