What a speed ramp is
A speed ramp changes playback speed inside one clip. The play runs at full speed, slows for the moment worth seeing twice, and speeds up again. It keeps the energy of real time and still gives the viewer a clear look at the catch, the release or the finish. Both charts above are drawn from the same kind of data: the speed at each point in the play, the frame rate it was shot at, and the frame rate of the finished video.
Why frame rate decides how slow you can go
Video is a run of still frames. A finished video usually plays 24, 30 or 60 of them each second. To show a moment at quarter speed with every frame unique, the camera had to record four times as many frames as the finished video plays. That gives a simple rule: the slowest smooth speed is the output frame rate divided by the capture frame rate.
| Shot at | Finished at 30 fps | Finished at 24 fps |
|---|---|---|
| 60 fps | 50% slowest smooth speed | 40% |
| 120 fps | 25% | 20% |
| 240 fps | 12.5% | 10% |
When footage goes too slow
This chart shows a power clean filmed on a phone at 60 fps and slowed to 40 percent. That is below the 50 percent floor, so the editor has to fill gaps. There are two ways to do that. Frame blending mixes neighboring frames, which looks soft. Optical flow builds new frames from the motion, which works on smooth movement and falls apart around fast hands, a spinning ball or a barbell passing a busy background. We'll tell you which plays can slow cleanly and which can't before the edit.
Filming for slow motion
- Set the phone or camera to 120 or 240 fps before the game or session, since you can't add frames later
- Use bright light: high frame rates need more of it, and night games and dim gyms add grain
- Watch for flicker under some arena and gym lights, which shows as banding in slow motion
- Keep the camera still and frame a little wider than you think, so a slowed play can be cropped in
- Record the whole play from start to finish, so the ramp has full speed footage on both sides
Where slow motion helps
It suits moments that happen too fast to read: a catch at the sideline, a goalkeeper's save, the bat meeting the ball, a sprinter's lean, the catch position of a clean. It works less well over long stretches. A reel that slows every play loses pace, so we save it for the plays that need it.
Questions
My phone only shot at 30 fps. Can you still slow it down?
A little. Slowing 30 fps footage much below full speed means building frames that weren't recorded, which can look smeared. Send a sample clip and we'll say what's realistic.
Can you slow down game film from a team platform?
Game film is often recorded at a standard frame rate and compressed, so heavy slow motion rarely looks good. A short, gentle slowdown on one moment usually works.
Got game film or gym footage? Tell us the sport, what you want made from it, and the date you need it.
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