CampaignReel

Ad placement specs against what generators output

Seven shapes against two, on comparable products

Two pages describing performance-driven products publish very different shape lists: seven values including 21:9 and 9:21 on one, and widescreen or vertical on the other. The products answer similar briefs and the shape columns do not. As of 2026-09-22.

Where the extra five shapes are usedEvery surface this register reads is served by widescreen or vertical. The gap that a booked placement notices is square, and the rest is reuse beyond the slot.Shapes the two pages publish16:9 and 9:16On both lists, and enough for every surface read here1:1Accepted from 640x640 by one surface; on one list only4:3 and 3:4On one list; no surface here states either21:9 and 9:21On one list; panels and overlay-heavy frames, not placementsWhat each one is actually for
Fig. 1 Two products with the longest runs in the register sit at opposite ends of the shape column.
What each page puts in writingFilled where the page states something in that column, hollow where it does not address it.What each page puts in writingHedraHeyGenWidescreen and verticalWidescreen and vertical — Hedra: Both listedWidescreen and vertical — HeyGen: Both listedSquareSquare — Hedra: ListedSquare — HeyGen: Not statedUltrawideUltrawide — Hedra: 21:9 and 9:21 both listedUltrawide — HeyGen: Not stated
Fig. 2 Filled where the page states something in that column, hollow where it does not address it.
The two shape lists, against what a surface asks for. Recorded 2026-09-22.
What the pages stateHedraHeyGen
Widescreen and verticalBoth listedBoth listed
SquareListedNot stated
Ultrawide21:9 and 9:21 both listedNot stated

Inclusion rule. Shapes each page publishes, compared only against the shapes a platform in this register states it accepts. A shape reachable by cropping is not a published output shape. Order. The shapes both lists share, then the ones only one has.

1Where the two lists actually differ for advertising

Every surface this register reads is served by widescreen or vertical, so for a booked placement the two rows are equivalent. The gap opens on the square option one platform accepts from 640x640 upward, which one list carries and the other does not.

Beyond that the extra values are for reuse rather than for a slot. An ultrawide strip is a panel in a designed layout; a vertical ultrawide survives heavy interface overlay. Neither is a placement in this register.

2A short list can be the more precise cell

The two-value row publishes output dimensions as a range from 128 to 4,096 pixels a side, so inside its two shapes it can be asked for an exact frame. The seven-value row publishes three named rungs instead.

So one page offers more shapes and less control over size, and the other the reverse. Which is better depends entirely on whether the campaign is fighting a shape gate or an upload check, and the register records both rather than choosing.

3Both lists are unconditional, which is rarer than it sounds

Neither page attaches a tier or a length to any shape. Two other entries in this register do, and a plan carrying a rule learned from those will look for a condition that is not there.

What neither page states is a default. An unset field has no documented behaviour on either row, which puts them in the same position as most of this column: the shape has to be supplied on every request or nothing on the page predicts the result.

4The rest of the column behind these two

Aspect ratio across the registerHedra is marked; HeyGen sits at two values, the shortest list among the rows that publish one in the same column. Recorded 2026-09-22.Aspect ratio across the registerAspect ratioAmazon Nova Reel — Aspect ratio: Not statedAmazon Nova ReelCogVideoX — Aspect ratio: Not statedCogVideoXGoogle Veo — Aspect ratio: 16:9 and 9:16Google VeoGrok Imagine — Aspect ratio: Seven, 16:9 the defaultGrok ImagineHedra — Aspect ratio: Seven, including 9:21 and 21:9HedraHeyGen — Aspect ratio: 16:9 or 9:16HeyGenKling AI — Aspect ratio: Not statedKling AILTX-Video — Aspect ratio: Not statedLTX-VideoMiniMax — Aspect ratio: Six, required for text-to-videoMiniMaxPika — Aspect ratio: Not statedPikaPixVerse — Aspect ratio: Eight on version 6PixVerseRunway — Aspect ratio: Seven pixel pairsRunwaySceneMixer — Aspect ratio: 9:16 and 16:9SceneMixerVidu — Aspect ratio: Not statedViduWan 3.0 — Aspect ratio: Six, adaptive by defaultWan 3.0
Fig. 3 Hedra is marked; HeyGen sits at two values, the shortest list among the rows that publish one in the same column. Recorded 2026-09-22.
Every generator in the register on the aspect ratio column, with Hedra marked. Recorded 2026-09-22.
GeneratorAspect ratio
Amazon Nova ReelNot stated
CogVideoXNot stated
Google Veo16:9 and 9:16
Grok ImagineSeven, 16:9 the default
HedraSeven, including 9:21 and 21:9
HeyGen16:9 or 9:16
Kling AINot stated
LTX-VideoNot stated
MiniMaxSix, required for text-to-video
PikaNot stated
PixVerseEight on version 6
RunwaySeven pixel pairs
SceneMixer9:16 and 16:9
ViduNot stated
Wan 3.0Six, adaptive by default

Inclusion rule. Every generator this register carries, on the one column this pair disagrees about. Rows that state nothing keep their place and are marked hollow. Order. Alphabetical by generator name.

Why these two. The two entries with the longest single runs in the register sit at opposite ends of the shape column, which means the axis that decides acceptance is not the axis either product is usually chosen on.

5Sources

Read from the Hedra Character-3 model page and the HeyGen usage limits page, both checked 2026-09-22. The column is described on aspect ratio, and each entry has its own cell page at Hedra and HeyGen, and the rule that keeps surfaces and generators apart is on method. Nearby pairs: Runway and MiniMax, Wan 3.0 and MiniMax.