Demand Gen 4:5 video 1080x1350: the API has 3:4, not 4:5

Sume's video aspect_ratio values include 3:4 but not 4:5, so you cannot request a 1080x1350 video directly from the video endpoint. Google's Demand Gen spec, read 2026-09-30, lists "Recommended pixels for HD: 1080x1350" for vertical 4:5, so you need a different route to reach it.

Which ratios does the video API accept?

The Video API page lists auto, adaptive, 21:9, 16:9, 4:3, 1:1, 3:4 and 9:16. The video generation page describes 3:4 as standard portrait and says each model advertises the subset it accepts in supported_aspect_ratios, so read that for your model.

What are my options for 4:5?

One: the first-party Slideshow Format. Its catalog prompt says "Default aspect 4:5", so a slideshow cut from product stills starts from that shape. Two: generate at 3:4 or 9:16 and crop to 4:5 in a post step; the options for trimming and cropping are compared in crop and trim: tool vs API.

A 3:4 clip is a different shape from 4:5, so do not upload it unchanged and assume it matches the 1080x1350 recommendation. Check the pixel size of the final file yourself.

When is 9:16 the simpler choice?

The spec also lists vertical 9:16 at 1080x1920, and 9:16 is a ratio the video API accepts. If your placements take 9:16, you can avoid the 4:5 question; the platform-by-platform tradeoff is in 4:5 vs 9:16 ad video.