Speed-ramp a locked beat, not a candidate whose duration is still moving
edit_video can slow, speed, or ramp a described section. Ramping a miss, or ramping before picture lock, rewrites a clock you will throw away — and every later caption with it.
Speed is an EDL instruction, not a keyframe graph. You tell edit_video to play the first three seconds at half speed, then normal. It builds the edit list. Fine-grained curves are not the interface; preview is how you check. Audio pitch will shift unless you say otherwise. All of that assumes a clock that is allowed to change on purpose. If the take might still regen, you are rewriting a clock that will not exist, and you will recaption, rescore, and retime overlays again.
Change a video's playback speed is the job. Free 480p preview with a cooldown, then editor_export. estimate_cost for the final.
Duration is a finishing contract
Slow-mo doubles seconds. A speed-up deletes them. Timed text, music tails, VO spotting — all of them assume the duration you have after the ramp, not before. Do the ramp on the keeper before those passes, or include the ramp in one edit_video assembly of keepers. Do not caption real-time then slow the file. Cues will drift.
People ramp first because slow-mo looks like craft. Craft on a miss is a trailer for a movie you will not make. If the product reveal is the wrong product, half-speed will not help.
Specify pitch: keep it natural, or let it chipmunk. Silence on that point is how a VO survives a speed-up as a cartoon, on a file you otherwise liked.
The AI video generator made the real-time take. Speed is a child.
Order
- Approve the take at 1×.
- Preview the ramp on that file. Check pitch.
- Export. Then music and captions against the new duration.
If you needed a true time-lapse of a long event, that is a different parent, not a 8× panic on a 6-second maybe.
FAQ
Can I ramp only the middle?
Yes, as a description, on a keeper. Preview. Very fine ramps may not match an NLE curve. Do not discover that on a miss you also hate for other reasons.
Should I extend the clip instead of slowing it?
extend_video generates new frames after the end. Slow-mo stretches existing ones. Different tools, both later, both wrong on a take you dislike.
Does preview:true apply the speed change?
Yes, at 480p. Use it to inspect the keeper's ramp. Do not spend the cooldown on a bin of experiments you have already rejected at 1×.
What happens to native audio?
It stretches or compresses with the picture unless you replace it after. If the line must stay intelligible, replace VO after the ramp on the locked picture, or mix a new read to the new clock.