App Store preview video length: 15-30 s, 30 fps max

Apple's app preview specifications list a length of 15-30 seconds and a maximum frame rate of 30 frames per second. If you make the preview with Sume, set output.fps to 30 yourself: when it is omitted, Timeline renders at the rate your sources already run at, so a 60 fps source stays 60.

Apple figures are from its specifications page and the September 9, 2026 release notes; Sume figures from the Timeline docs, read 2026-09-30.

What does Apple list for app previews?

How do I keep a Sume render at 30 fps?

Allowed output.fps values are 24, 25, 30 and 60. Set 30. Timeline also warns about frame-rate resampling: a rate that differs from a source's is met by repeating or dropping frames, which can judder on motion, and the render reports output_fps_resamples_sources. If the source is already 30 fps, nothing is resampled; see Timeline frame-rate judder warning.

Can I set the size and length too?

Timeline's default output is 1080x1920, so pass output.width 886 and output.height 1920; even integers from 256 to 2160 are allowed. audio.duration_seconds sets the output length. To shorten an existing clip, Video trim takes start plus end or duration, and its output field can set width, height and fps (exact precision only).

Does this make the preview approved?

No. These steps only match the length, size and frame-rate figures on Apple's page. Apple's other requirements and App Store Connect upload are yours to check; the notes say iPhone Duo upload support comes later this year.