A flat speed change (a whole clip at 50% or 200%) is useful, but a speed ramp — a gradual, keyframed shift in speed within a single clip — is what gives modern, high-energy edits their signature feel. This lesson covers building ramps by hand and cleaning up the motion with frame interpolation.
Time Remapping vs. Clip Speed
The Speed/Duration dialog (covered earlier) changes a clip's speed uniformly. To vary speed within a clip, use Time Remapping instead:
- Select the clip and open Effect Controls
- Twirl open the "Time Remapping" property (under the clip's video effects)
- Right-click the speed line that appears in the clip on the timeline and choose "Add Keyframe" at the points where speed should change
Each keyframe pair defines a segment — the speed between two keyframes can be dragged up or down independently, letting one clip slow down, speed up, and slow down again without needing to cut it into separate pieces.
Building a Basic Ramp
A common pattern — normal speed, ramp into slow motion for emphasis, then back to normal:
- Add a keyframe just before the moment you want to emphasize (speed still 100%)
- Add a second keyframe a few frames later, at the peak of the moment, and drag the segment between the two keyframes down to 20-40%
- Add a third keyframe after the moment, ramping back up to 100% over a similar short window
Keep the ramp itself short (a handful of frames) — the ramp should feel like a snap of emphasis, not a slow drift, unless you're deliberately going for a dreamy effect.
Frame Blending vs. Optical Flow
Slowing footage down means displaying frames that don't actually exist in the original capture — Premiere has to generate them. Two methods, set in the Speed/Duration dialog or Time Remapping options:
- Frame Sampling — repeats existing frames; fast to render but looks choppy at slow speeds
- Frame Blending — blends adjacent frames together; smoother than sampling, works fine for moderate slow-motion
- Optical Flow — analyzes motion between frames and generates genuinely new in-between frames; the smoothest option, but slower to render and can produce visible artifacts around fast, complex motion (hair, water, overlapping limbs)
For heavy slow motion (below 30%), Optical Flow is usually worth the render time. For subtle ramps, Frame Blending is often indistinguishable and renders faster.
Shooting for Speed Ramps
Speed ramps look best on footage shot at a higher frame rate than your sequence (footage shot at 60fps or 120fps, ramped down within a 24fps or 30fps sequence) because there's genuinely more real information to slow into, reducing reliance on generated frames. Ramping standard 24fps/30fps footage down works but leans more heavily on Optical Flow to fill gaps, with a higher chance of artifacts.
Zoom and Whip-Pan Transitions
Beyond dissolves, two transition styles common in fast-paced edits:
- Zoom transition — the outgoing clip zooms in rapidly to a blur, and the incoming clip zooms out from a matching blur; built by keyframing Scale on both clips into a fast blur-through, matched at the cut point
- Whip pan — a fast camera pan (either shot in-camera or simulated by rapidly keyframing Position) blurs the frame, and the incoming clip continues the motion, hiding the cut inside the blur
Both rely on hiding the cut point inside motion blur so it feels seamless. They're intensive to build manually and easy to overuse — reserve them for content where high energy is the point (montages, promos, sports/gaming highlights), not for measured or narrative content.
Keeping Ramps Purposeful
It's easy to over-apply speed ramping once you know how — every clip does not need one. Use a ramp to emphasize a genuine highlight (impact, punchline, reveal), not as a default transition between every pair of clips. A video where everything ramps loses the contrast that made the technique feel special in the first place.