The five shapes a length figure takes
Every figure in a duration column is a number of seconds, and that is the least informative thing about it. The shape of the statement decides whether a beat can be asked for at its real length, rounded, multiplied or abandoned. As of 2026-09-12.
| Form | What it permits | What a shot list has to do |
|---|---|---|
| A ceiling | Anything up to the figure | Nothing; write the beat and stay under it |
| A range | Anything between two figures | Keep the beat inside both ends |
| A menu | Only the listed values | Round the beat to a listed value |
| An increment | Multiples of one figure | Express the whole piece in that grain |
| A fixed value | One length | Divide the slot and accept the remainder |
Inclusion rule. The forms a length statement takes across published specification pages. A form that appears only in marketing copy rather than in a specification is not listed. Order. Most permissive form first.
1A ceiling and a fixed value are opposite facts
Both are single numbers. A ceiling says nothing longer; a fixed value says nothing else at all. Against a slot the first is an upper bound to stay under and the second is a divisor, and the arithmetic they produce is different in kind.
The mistake is easy to make in either direction. Reading a fixed value as a ceiling produces a plan that asks for four seconds and gets six. Reading a ceiling as a fixed value produces a plan that generates more pieces than it needs.
2An increment is the form that rewrites the brief
Where legal lengths are multiples, the slot has to be expressed in that grain before anything is requested. There is no rounding: an awkward value has no nearest legal neighbour, it has two, and one of them is longer than the slot.
This is the only form where the constraint reaches the writing rather than the edit. Everywhere else a beat can be generated and trimmed; here the beat count is fixed before a word of the script is settled.
3A menu is a range with the middle removed
Three listed values look like a small range and behave like a choice. A seven second idea becomes a six second idea or an eight second idea, and which one depends on what the line has to say rather than on what is cheapest.
Menus also carry conditions more often than ranges do, because the values are discrete enough to annotate. When one value on a menu is only available in some circumstance, the menu is really two shorter menus and the cell should say so.
A craft note, not a spec. Nothing here is taken from a platform or a vendor, and nothing here should be quoted as a requirement. The sourced material is on published limits. Related: What not stated means, Rate cards and references.
4From brief to placement
For ad work around “Reading a duration cell”, SceneMixer's pages explain how its ad projects are produced:
The script is written from the photos and the one-line description. In step-by-step mode you can rewrite it before anything is shot.
SceneMixer, How to Make an Ad from One Photo — “Do I need a script?” (read 2026-10-13)
A segment is one generation, and its length is the sum of its shots’ seconds.
SceneMixer, How to Change a Segment’s Duration, and Which Tiers Accept 30 Seconds (read 2026-10-13)