LTX-2.5 Pro offers 6, 8 or 10 s clips; Sume rows take any whole second

On fal's LTX-2.5 page the Pro variant makes clips of 6, 8 or 10 seconds, so a 7-second clip is not on its menu. Sume lists no LTX id; for exact whole-second lengths it offers rows whose range covers any integer between a minimum and a maximum, such as 3 to 10 seconds on gemini-omni-flash-1.1.

Read on 2026-10-07: fal's LTX-2.5 page and Sume's video docs.

What the LTX-2.5 page lists

The page also describes an Auto Duration option that picks the clip length from the described action. It lists native multishot generation and a community license that requires a paid license for entities with annual revenue of at least $10 million.

Whole-second ranges on Sume

Sume's catalog gives each row a minimum and a maximum, and your duration is an integer in that range. The 7-second case works on all four rows below.

When 6, 8 or 10 is fine

Fixed lengths suit templated work, where every ad is 8 seconds. They hurt when a sentence of narration runs 7.4 seconds, because you either clip speech or pad a second. A catalog that accepts any whole second lets you round up to the narration and trim the tail afterwards.

• Measure the narration first, then round up to the next whole second.
• Check the row's minimum: H3 starts at 5 seconds, so a 3-second sting cannot be an H3 job.
• For clips over 15 seconds, the four rows above stop short; Wan 3.0 (2 to 30 s) and Seedance 2.5 (4 to 30 s) reach 30, per the docs.

Rounding to narration

Narration sets the clip length in most explainer and ad work. With fixed lengths of 6, 8 or 10 the nearest choice may be a second shorter or longer than you want. With any whole second in the range, you pick the length that fits and trim.

Costs follow the length linearly on the Sume rows, so each second you save is the per-second rate. On gemini-omni-flash-1.1 at 720p, 9 seconds is $1.13 and 8 is $1.00.

• Time the narration with a stopwatch, not a word count.
• Round up to the next whole second and cut the end in assembly.
• Check the row's minimum and maximum before you commit to a length.

What the fal page does not settle

The page lists duration, resolution and price, but it does not tell you how the model behaves on your own prompts. It states that entities with annual revenue of $10 million or more need a paid commercial license from Lightricks; read the license text itself if that applies to you.