Omni edit duration is only a reserve hint: 8 seconds by default

On a Gemini Omni Flash 1.1 edit, the duration field does nothing to the output. The source clip sets the output length. Sume uses duration only as a hint when it reserves credits at submit, and it defaults to 8 seconds when you leave it out. The Video Router docs mark the underlying point as needing verification: the provider does not return an output duration, so the reserve is a hint, not a probe of your file.

What an 8-second hint means in dollars

Sume's prices are the provider list times 1.25. The fal list for the model is $0.03, $0.10, $0.15 and $0.30 a second at 360p, 720p, 1080p and 4K (fal, 2026-08-28, as recorded in the repo's catalog notes), which gives these per-second rates and 8-second reserves.

How to set it

If your source is longer than 8 seconds, send a duration close to its real length so your balance check and reserve match the clip. If it is shorter, the default hint over-reserves, which is harmless for the balance. Either way the output length is the source's length, so confirm it afterwards: the video-inspect API probes a clip, and its probe tells you the true duration before you join the edit into a timeline.

Do not read the hint as a trim control. To make a shorter edit, cut the clip first with the video-trim API and edit the trimmed file.

• Send duration equal to the source length rounded up, for a faithful reserve.
• Leave it out for clips of about 8 seconds or less.
• Use /v1/usage after the job to read what was actually charged; do not assume it equals the hint.