Aspect ratio: the spec that cannot be fixed later
Aspect ratio is the shape of the frame. It is published either as a name, such as sixteen by nine, or as a pair of pixel counts. Unlike resolution it cannot be revisited after a render: a surface either takes the shape or it does not. As of 2026-09-12.
| How it is published | What it settles | What it leaves out |
|---|---|---|
| A ratio name | The proportion | How many pixels arrive |
| A pixel pair | The proportion and the size | Nothing, on that one value |
| A resolution alone | Nothing about shape | Whether another shape is available |
| Nothing | Nothing | Whether a vertical output exists at all |
Inclusion rule. Forms a shape statement takes on a specification page. A proportion derived from a published resolution is not treated as a published shape. Order. The most common form first.
1Why it is a gate and resolution is not
A file at the wrong resolution can be re-exported, and a softer picture is a compromise. A file in the wrong shape has to be cropped, and cropping keeps a rectangle from inside the frame rather than making the same picture smaller.
So whatever the composition was built around may simply be outside the new rectangle. That is a regeneration rather than an adjustment, which is why shape belongs at the beginning of a brief and not at the end.
2A resolution does not answer the shape question
An exact pixel pair implies a proportion, and a single pair says only what one output looks like. It cannot say whether the parameter accepts another value, and a placement plan needs that second answer.
That is why a register should leave the shape cell empty on a page that publishes pixels and no ratio. Filling it from arithmetic would make the page look as though it had confirmed a vertical output exists.
3Vendors publish it least and it matters most
Shape is rarely charged for, so rate cards omit it. Resolution is charged for, so it appears almost everywhere. The column that decides whether a piece can run at all is the one most often left blank.
The practical response is to get it in writing before booking media. Almost every product can produce a vertical frame; a media plan that has to be signed off runs on statements rather than on likelihood.
A vocabulary entry: the definition, plus how the specification pages on these sheets usually publish it. Table checked 2026-09-12. Nearby entries: Resolution tier, Bitrate.
4Making the ad itself
For ad work around “Aspect ratio”, SceneMixer's pages explain how its ad projects are produced:
The layout follows the project's aspect ratio, which is set when the project starts.
SceneMixer, How the Episode Editor Lays Out Vertical (9:16) and Landscape (16:9) Projects — “Can I switch between the two layouts?” (read 2026-10-13)
16:9 landscape (SceneMixer's default) and 9:16 vertical (the usual short-drama frame), chosen per project.
SceneMixer, Seedance 2.0 in a Real Short-Drama Pipeline — “Which aspect ratios does the pipeline generate?” (read 2026-10-13)