Shape decides more than resolution does
Masthead is stated as widescreen or 16:9, autoplaying without sound for up to 30 seconds on desktop. Nine of the 15 tools here name 16:9 among their shapes and three of those make it the default; six state no shape anywhere this register reads. As of 2026-09-19.
| Item | What is published | Detail |
|---|---|---|
| Masthead | Widescreen or 16:9 | Stated by Google |
| Google Veo | 16:9 default, 9:16 available | Stated in the documentation |
| Grok Imagine | 16:9 default, seven in all | Stated in the documentation |
| SceneMixer | 16:9 default, 9:16 available | Stated on the vendor site |
| Wan 3.0 | adaptive default, 16:9 available | Stated in the API reference |
| Pika, Kling AI, Vidu and three more | Not stated on the page read | Resolution published, shape not |
Inclusion rule. Format requirements from Google's help page; tool shapes from the vendor's own pages. The two sources are never mixed in one cell. Order. Format first, then tools that publish a shape.
1A wrong-shaped file cannot be fixed by re-encoding
Resolution can be changed after the fact with a loss nobody notices. Shape cannot: re-cropping generated footage moves faces out of frame, and generated footage has no headroom to spare because nothing was composed for a crop.
So shape is the spec that has to be right at generation time, and it is the one least often published next to a price.
2A widescreen default matches this placement, and misses the vertical ones
A tool defaulting to 16:9 produces a Masthead-shaped file with no setting touched, and a Masthead is explicitly 16:9. Google Veo, Grok Imagine and SceneMixer all publish that default, so for this placement the default and the requirement agree before anything is generated.
The same default works against a vertical placement: there the setting has to be switched to 9:16 before the first second exists, which is exactly the kind of step that gets discovered after the footage does. Wan 3.0 is the awkward case, because its default is adaptive rather than a shape, so what arrives depends on the reference frame somebody chose for its content.
3Six tools publish resolution and not shape
Resolution appears on priced pages because it is priced, and on model cards because a card reports what the weights emit. Shape is priced almost nowhere and reported on a card only when it is fixed, which leaves the more consequential spec undocumented on six of the 15 rows here, including both entries that publish nothing but a resolution and a frame rate.
The register records that as not stated rather than assuming a default, because assuming is how a vertical file ends up in a widescreen slot.
- Aspect ratios16:9 by default, with 9:16 availablestated on the site
- MastheadWidescreen or 16:9, autoplaying without sound for up to 30 seconds on desktopreservation only
4Sources
Format requirements come from Google Ads Help, read 2026-09-12, and tool limits from each vendor page listed on published limits, read 2026-09-19. The rule against mixing the two is on method. Nearby: Resolutions, The first five, Past the ceiling.