Introduction

Transform video straight from a URL — thumbnails, resizing, trimming, rotation, and GIF, with no SDK or build step.

Video transforms turn a source video into a thumbnail, resized clip, GIF, or reoriented file by adding tokens to the delivery URL — the same URL pattern you use for images. You put transform tokens in the path; the CDN renders and serves the result.

You can use video transforms for:

• Preview thumbnails for cards and listing pages (thumb_ar)
• Resizing and aspect-ratio conversion for a specific player or platform (w_, h_, ar_)
• Trimming a long video down to a short clip (so_, eo_, d_)
• Converting a segment into a GIF for silent previews (f_gif)
• Correcting orientation with rotation and mirroring (r_, flip_h, flip_v)

Video transforms are processed asynchronously. The first request for a new transform triggers a render and returns a JSON status; once the render completes, the same URL serves the output from cache. thumb_ar returns a WebP image, f_gif returns a GIF, and every other transform returns video.

What does a video URL look like?

Every delivery URL follows the same anatomy: domain, workspace ID, transforms, video path.

https://assets.autorender.io/LOKVTtKVGb/w_500,ar_1:1/doc/skateboarding.mp4

https://assets.autorender.io/LOKVTtKVGb/w_500,ar_1:1/doc/skateboarding.mp4

• assets.autorender.io — the Autorender delivery CDN.
• LOKVTtKVGb — your workspace ID, which prefixes every delivery URL.
• w_500,ar_1:1 — comma-separated transform tokens.
• doc/skateboarding.mp4 — the path to your source video.

Combine tokens in one URL, comma-separated. Order does not need to match any reference table.

How does async processing work?

The first request for a new transform returns a JSON status instead of the file:

1. {"status":"triggered"} — the request is received and queued.
2. {"status":"processing"} — the render is running.
3. Once the render completes, the same URL serves the transformed file directly.

Retry or poll the URL until it serves the asset. Subsequent requests return the cached output.

Transform tokens

Category	Token	Example	What it does
Thumbnail	thumb_ar	thumb_ar	Thumbnail that preserves aspect ratio, returned as WebP
Dimensions	w_{n}	w_500	Output width in pixels
	h_{n}	h_500	Output height in pixels
	ar_{ratio}	ar_1:1	Output aspect ratio
Fit mode	cm_pad_resize	cm_pad_resize	Resize to fit the box and pad the empty space
	cm_extract	cm_extract	Crop to fill the exact box
Background	bg_{color}	bg_white	Padding color as a name or hex value
Time	so_{sec}	so_5	Start offset in seconds
	eo_{sec}	eo_15	End offset in seconds
	d_{sec}	d_10	Clip duration in seconds
Format	f_gif	f_gif	Output as GIF
Flip	flip_h / flip_v / flip_hv	flip_h	Mirror horizontally, vertically, or both
Rotation	r_{deg}	r_90	Rotate by 90°, 180°, or 270°

The w_, h_, ar_, bg_, r_, and flip_ tokens behave the same for images. See the shared image pages for resize and aspect ratio, rotate, and flip.

Width and height are rounded to even values before encoding, because common video codecs require even dimensions. A request for an odd dimension is snapped to the nearest even pixel.

Next steps

Thumbnail

Generate a WebP preview image from any video.

Resize & aspect ratio

Set exact dimensions or force a ratio for any player.

Trim

Clip a segment by start and end offset or duration.

Convert to GIF

Turn a video segment into a lightweight GIF.