Overview

Scenario's Content Delivery Network provides secure, signed access to your assets with real-time transformation capabilities. The CDN delivers images, 3D models, and videos with features including resizing, format conversion, and optimization.

CDN Domain: cdn.cloud.scenario.com

URL Structure

Path Patterns

Pattern	Purpose	Access
`/assets/*`	Original asset files	Requires signed URL
`/assets-transform/*`	Transformed assets (resized, converted, etc.)	Requires signed URL
`/thumbnails/*`	Asset thumbnails	Public

Signed URLs

All asset URLs (except thumbnails) are signed for security and expire automatically.

Expiration Policy

Signed URLs use a rolling expiration window optimized for caching:

Date Range	Expiration Date
1st - 7th	14th of same month
8th - 14th	21st of same month
15th - 21st	Last day of same month
22nd - 31st	7th of next month

Minimum expiration: 24 hours from generation

Signed URLs include signature parameters (Policy, Signature, Key-Pair-Id) that are automatically added by the API.

⚠️ Never change the given signature query strings, it would result in an Access Denied Error.

Asset Transformation

Transform assets on-the-fly using the /assets-transform/{assetId} endpoint with query parameters.

Image Transformation Parameters

Parameter	Type	Default	Values	Description
`width`	integer \| "auto"	auto	> 0	Target width in pixels
`height`	integer \| "auto"	auto	> 0	Target height in pixels
`quality`	integer	100	1-100	Compression quality
`format`	string	origin	See below	Output format
`fit`	string	cover	cover, contain, fill, inside, outside	Resize mode
`rotate`	integer	0	0-360	Rotation in degrees
`blur`	integer	0	0-100	Blur strength
`greyscale`	boolean	false	true, false	Convert to greyscale
`flatten`	boolean	false	true, false	Remove transparency
`background`	string	ffffff	Hex (no #)	Background color when flattening

Supported Formats

Image Formats:

jpeg / jpg - JPEG
png - PNG with transparency
webp - Modern WebP format
avif - Next-gen AVIF format
tiff / tif - TIFF
origin - Keep original format
auto - Auto-select best format

3D Model Formats:

glb - Binary glTF
obj - Wavefront OBJ
fbx - Autodesk FBX

Resize Modes (fit parameter)

cover (default) - Crop to fill dimensions, maintains aspect ratio
contain - Scale to fit within dimensions, may add letterboxing
fill - Stretch to exact dimensions, may distort
inside - Scale down to fit within dimensions only
outside - Scale to cover dimensions, may crop

Example Transformations

# Resize to 512x512, convert to WebP
https://cdn.cloud.scenario.com/assets-transform/{assetId}?width=512&height=512&format=webp&quality=90&Policy=...&Signature=...&Key-Pair-Id=...

# Auto-width, 1024px height, maintain aspect ratio
https://cdn.cloud.scenario.com/assets-transform/{assetId}?height=1024&width=auto&fit=inside&Policy=...&Signature=...&Key-Pair-Id=...

# Convert to greyscale with slight blur
https://cdn.cloud.scenario.com/assets-transform/{assetId}?greyscale=true&blur=5&Policy=...&Signature=...&Key-Pair-Id=...

# Convert 3D model to GLB format
https://cdn.cloud.scenario.com/assets-transform/{assetId}?format=glb&Policy=...&Signature=...&Key-Pair-Id=...

# Flatten transparency with custom background
https://cdn.cloud.scenario.com/assets-transform/{assetId}?flatten=true&background=000000&Policy=...&Signature=...&Key-Pair-Id=...

API Usage

Get Asset Download URL

Generate a signed download URL with optional format conversion.

Endpoint: POST /v1/assets/{assetId}/download

Request:

{
  "targetFormat": "webp"  // Optional - any supported format
}

Response:

{
  "url": "https://cdn.cloud.scenario.com/assets-transform/{assetId}?format=webp&Policy=...&Signature=...&Key-Pair-Id=..."
}

Asset Object URLs

When retrieving assets through the API (e.g., GET /v1/assets), the response includes a pre-signed url field:

{
  "assets": [{
    "id": "asset-id",
    "url": "https://cdn.cloud.scenario.com/assets-transform/{assetId}?...",
    ...
  }]
}

These URLs are already signed and ready to use.

Caching

Transformed assets are cached for faster subsequent access
Cache duration: Up to 24 hours (respects signed URL expiration)
Cache key: Based on asset ID and transformation parameters

For consistent cache hits, use the same transformation parameters. Varying parameters (e.g., width=512 vs width=513) will create separate cache entries.

Best Practices

Performance

Use WebP or AVIF for modern browsers to reduce bandwidth
Specify exact dimensions when possible to optimize caching
Set appropriate quality (80-90 typically sufficient for web)
Use fit=inside to prevent upscaling small images

Format Selection

PNG: When transparency is required
JPEG: For photos without transparency
WebP: Best compression for modern browsers
AVIF: Smallest file size, newer browser support
Auto: Let the CDN choose based on browser support

Dimensions

Thumbnails: 256x256 or 512x512
Preview: 1024px on longest side
Full quality: 2048px or original size
Use auto for one dimension to maintain aspect ratio