thumb_ar extracts a frame from your video and returns it as a WebP image that keeps the source aspect ratio. Use it for previews, cards, and listing pages.
Thumbnails are returned as WebP, not video. The frame is rendered on the first request and served from cache thereafter.
How to use it?
Addthumb_ar as the only transform token in the path.
The first request triggers the render and returns a JSON status. Retry or poll the URL until it serves the WebP; see async processing for the status flow.
Next steps
Resize & aspect ratio
Set exact dimensions or force a ratio for the source video.
Video overview
See every video transform token and how async rendering works.