User Assets

Create upload link

Step 1 of uploading an asset: get a link to upload the file to, and the fileKey to confirm it with.

POSThttps://api.sangtao.ai/v2/user-assets/presign

Authorization

X-Api-Keystring · headerrequired
Your API key, from the API keys page of your account.

Upload and manage user media assets (videos, images, audio). Assets are used as intro/outro videos, logos, watermarks, background music, voiceovers, and thumbnails in video creation.

Files here are kept until you delete them, within each category's limits. Only need an image as a reference for the next image you create? Upload a reference image (temporary, deleted after 1 day).

Body

fileNamestringrequired
Original file name (e.g. "logo.png")
contentTypestringrequired
MIME type (e.g. "image/png", "video/mp4")

Response

uploadUrlstring
Where to send the file (step 2). Write access to this one file only; no X-Api-Key needed
methodstring
The method for that request: "PUT"
headersobject
Send exactly these headers with the file (Content-Type, and x-ms-blob-type when it is there) — read them from here, do not write them in your code
urlstring
Where the file can be read once uploaded
fileKeystring
The file's key — send it to confirm (step 3)
expiresInnumber
Seconds until uploadUrl stops working (600). Use this one.
expiresAtstring
The same moment as a UTC time (ISO 8601) — kept for compatibility.
categorystring
Category worked out from contentType
Available options:videoimageaudiodocument
maxSizeBytesnumber
Largest file allowed for this category, in bytes
allowedContentTypesstring[]
MIME types this category takes

Errors

Status	errorCode	When
400	UNSUPPORTED_FILE_TYPE	The content type is not allowed for this category (see Category Limits)
429	QUOTA_EXCEEDED	The category's file count or storage cap is reached
500	UPLOAD_FAILED	The upload link could not be created (storage error) — try again

Upload Flow

text

1. POST /user-assets/presign  →  uploadUrl, method, headers, fileKey
2. PUT  uploadUrl (the file)  →  with exactly those headers
3. POST /user-assets/confirm  →  fileKey: the file becomes an asset

The presign response includes category, maxSizeBytes, and allowedContentTypes — use these for client-side validation before uploading.

Step 2: Upload the file

Send the file to uploadUrl with the method and exactly the headers the presign response gives. Then confirm it with fileKey — until then it is not an asset.

bash

curl -X PUT "UPLOAD_URL" \
  -H "Content-Type: image/png" \
  -H "x-ms-blob-type: BlockBlob" \
  --data-binary @my-logo.png

Purpose Values

Purpose	Used for
outro_video	Appended at end of rendered videos
intro_video	Prepended at start of rendered videos
logo	Overlay logo on video during render
watermark	Watermark overlay in render pipeline
background_music	Custom background music for all video types
voiceover	User-uploaded voice file (replaces TTS)
thumbnail	Custom thumbnail for published jobs
general	General reference files

Category Limits

Category	Content Types	Max Size	Max Items
video	video/mp4, video/webm	500 MB	20
image	image/png, jpeg, webp, svg+xml, gif	50 MB	100
audio	audio/mpeg, wav, ogg, aac	100 MB	30
document	application/pdf, text/csv, application/json	50 MB	20

Next, once the file is uploaded: Confirm upload registers it as an asset.

POST/user-assets/presign

curl -X POST "https://api.sangtao.ai/v2/user-assets/presign" \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "fileName": "my-logo.png",
    "contentType": "image/png"
  }'

{
  "success": true,
  "data": {
    "uploadUrl": "https://…/user-assets/1e65….png?sv=…&sig=…",
    "method": "PUT",
    "headers": {
      "Content-Type": "image/png",
      "x-ms-blob-type": "BlockBlob"
    },
    "url": "https://cdn.sangtao.ai/user-assets/1e65….png",
    "fileKey": "d15ed…/user-assets/1e65….png",
    "expiresIn": 600,
    "expiresAt": "2026-06-08T12:30:00Z",
    "category": "image",
    "maxSizeBytes": 52428800,
    "allowedContentTypes": [
      "image/png",
      "image/jpeg",
      "image/webp",
      "image/svg+xml",
      "image/gif"
    ]
  }
}

POST/user-assets/presign

curl -X POST "https://api.sangtao.ai/v2/user-assets/presign" \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "fileName": "my-logo.png",
    "contentType": "image/png"
  }'

{
  "success": true,
  "data": {
    "uploadUrl": "https://…/user-assets/1e65….png?sv=…&sig=…",
    "method": "PUT",
    "headers": {
      "Content-Type": "image/png",
      "x-ms-blob-type": "BlockBlob"
    },
    "url": "https://cdn.sangtao.ai/user-assets/1e65….png",
    "fileKey": "d15ed…/user-assets/1e65….png",
    "expiresIn": 600,
    "expiresAt": "2026-06-08T12:30:00Z",
    "category": "image",
    "maxSizeBytes": 52428800,
    "allowedContentTypes": [
      "image/png",
      "image/jpeg",
      "image/webp",
      "image/svg+xml",
      "image/gif"
    ]
  }
}

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