The short version
- Slowing video down spreads the same frames over more time. Too few frames looks choppy.
- Shoot at 60 fps for half speed, 120 fps for quarter speed, and higher for more extreme slow motion.
- A speed ramp changes speed smoothly within a clip — normal, then slow, then fast.
- Put the slowest part on the peak moment of the action, and time the ramp to the music.
Why slow motion sometimes looks choppy
Video is a series of still frames. Most phones record 30 frames per second. If you play that footage at half speed, each second of the original is stretched over two seconds — but there are still only 30 frames to show. The result is effectively 15 frames per second, which the eye sees as stutter.
Some editing tools invent new in-between frames to hide this (called frame interpolation or "optical flow"). It can help, but it also produces warping and smearing on fast motion. The reliable fix is to record more frames in the first place.
Which frame rate to shoot
To keep motion smooth, the slowed-down footage should still have at least around 24–30 frames per second. That gives a simple rule: the speed you can slow to is roughly 30 divided by your recording frame rate.
| Recorded at | Smooth down to | Good for |
|---|---|---|
| 24–30 fps | Full speed only (1×) | Normal footage; slight speed-ups |
| 60 fps | About 0.5× | Gentle slow motion, walking, dancing, B-roll |
| 120 fps | About 0.25× | Sports, splashes, hair flips, jumps |
| 240 fps | About 0.125× | Very fast action, water droplets, dramatic moments |
Higher frame rates need more light, because each frame gets less exposure time. Shoot slow motion outdoors or in bright rooms, and watch out for flicker under some indoor lights.
What is a speed ramp?
A speed ramp changes speed gradually within a single clip instead of cutting between speeds. A classic example: a skateboarder rolls in at normal speed, everything eases into slow motion as they leave the ground, then snaps back to speed as they land.
Ramps feel smoother than hard speed changes because the eye follows the motion as it decelerates, and they draw attention to exactly the moment you choose. Common shapes include:
- Normal → slow → normal ("Hero"): highlights a single peak moment.
- Fast → slow → fast ("Montage"): skims through the build-up and the aftermath, lingers on the highlight.
- Deep slow motion ("Bullet"): an extreme slowdown at the centre of the action for maximum drama.
- Fast into normal ("Flash in") or normal into fast ("Flash out"): energetic starts and exits, great at the beginning or end of a clip.
- Steady ramps up or down: a gradual acceleration or slowdown, useful for time-lapse-style build-ups.
Where to put the slow part
- On the peak of the action — the top of a jump, the moment a ball is struck, the splash, the reveal.
- On the beat. Let the music drive the ramp: speed up into a drop, slow down on a pause or a big hit. It's the single biggest factor in ramps feeling "right".
- Not too often. If everything is slow motion, nothing is special. One or two ramps per short video is plenty.
- With motion in the frame. Slowing a static shot does nothing. Ramps need movement — of the subject or the camera — to be noticed.
What happens to the sound
Slowing speech or natural sound down makes it deep and garbled, and speeding it up makes it squeaky. Most browsers also mute a clip's own audio at very high or very low speeds. That's why speed-ramped sections usually sit under music rather than original sound. Use the clip's audio for the normal-speed parts if you need it, and let a music track carry the ramp.
Step by step: create a speed ramp in VDOAPP
- Add your clip in the free online editor. If the action is in the middle of a long clip, trim it first so the ramp is centred on the moment you want.
- Open the Clip tab with the clip selected and find Speed curve.
- Pick a preset — Montage, Hero, Bullet, Jump cut, Flash in, Flash out, Ramp up or Ramp down. The editor previews the clip immediately and shows how long it now plays (for example "4.0s of footage → plays in 11.6s").
- Shape it by hand. Choose Custom, or drag the points of a preset: up for faster, down for slower (from 0.1× to 10×). Double-click to add a point; double-click a point to remove it. Points snap to 1× as you pass the middle line.
- Line it up with the music. Add a track in the Audio tab, then drag the curve's points so the slowest part lands on a musical hit.
- Preview and export. Press ▶ Preview clip to check the feel, then export.
Want to go faster instead? See our speed-up and time-lapse guide. Prefer a constant speed instead? The 0.25× to 3× buttons in the same tab apply a single speed to the whole clip. Choosing one replaces any curve.
VDOAPP slows footage by repeating frames rather than inventing new ones, so the frame-rate advice above applies: shoot at 60–120 fps for the smoothest slow motion.
Common mistakes
- Slowing 30 fps footage too far. Below about 0.5× it will stutter. Shoot at a higher frame rate next time, or keep that section closer to normal speed.
- Abrupt changes. Very steep curves feel jarring. Spread the change over a few frames either side of the peak.
- Motion blur in slow motion. Footage shot with a slow shutter smears when slowed. More light lets the camera use a faster shutter.
- Ramping every clip. Save it for the moments that deserve it.