POST
/
api
/
v1
/
generate
/
upload-extend
Upload And Extend Audio
curl --request POST \
  --url https://api.kie.ai/api/v1/generate/upload-extend \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "uploadUrl": "https://storage.example.com/upload",
  "defaultParamFlag": true,
  "instrumental": true,
  "prompt": "Extend the music with more relaxing notes",
  "style": "Classical",
  "title": "Peaceful Piano Extended",
  "continueAt": 60,
  "model": "V3_5",
  "negativeTags": "Relaxing Piano",
  "callBackUrl": "https://api.example.com/callback",
  "vocalGender": "m",
  "styleWeight": 0.65,
  "weirdnessConstraint": 0.65,
  "audioWeight": 0.65
}'
{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "5c79****be8e"
  }
}

​
Parameter Usage Guide

Character limits vary depending on the model version:
  • For models V4_5PLUS and V4_5: style (max 1000 chars), title (max 100 chars), prompt (max 5000 chars)
  • For models V3_5 and V4: style (max 200 chars), title (max 80 chars), prompt (max 3000 chars)
  • When defaultParamFlag is true (Custom Parameters):
    • If instrumental is true: style, title, and uploadUrl are required
    • If instrumental is false: style, prompt, title, and uploadUrl are required
    • Character limits vary by model version (see note above)
    • continueAt: the time point in seconds from which to start extending (must be greater than 0 and less than the uploaded audio duration)
    • uploadUrl: specifies the upload location for audio files; ensure uploaded audio does not exceed 8 minutes.
  • When defaultParamFlag is false (Default Parameters):
    • Regardless of instrumental setting, only uploadUrl and prompt are required
    • Other parameters will use the original audio’s parameters

​
Developer Notes

  1. Generated files will be retained for 14 days
  2. Model version must be consistent with the source music
  3. This feature is ideal for creating longer works by extending existing music
  4. uploadUrl parameter specifies the upload location for audio files; provide a valid URL.

​
Optional parameters

  • vocalGender (string): Vocal gender preference. Use m for male, f for female.
  • styleWeight (number): Strength of adherence to style. Range 0–1, up to 2 decimals. Example: 0.65.
  • weirdnessConstraint (number): Controls creative deviation. Range 0–1, up to 2 decimals. Example: 0.65.
  • audioWeight (number): Balance weight for audio features. Range 0–1, up to 2 decimals. Example: 0.65.

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

Response

200
application/json

Request successful

The response is of type object.