1x → 2x · 4x · 8x slower
Slow motion from a normal-speed video, without the stutter
Slow a 30fps clip down 4x and only 7.5 different pictures are left for each second of playback. If nothing new is made, each picture is simply held longer and the motion moves in steps. FrameSmoother's Slow Motion setting (2x, 4x or 8x) generates the in-between frames on the iPhone instead, so the slowed clip still plays at the frame rate you choose.
01Frame by frame
What one gap looks like at 4x
Each box is one frame of a 60fps result; the dot is where a moving object sits. Both rows cover the same stretch: from one original frame to the next, slowed down 4x.
Held: the same picture repeated until the next original frame
Generated: FrameSmoother computes 7 frames between the two originals
original frame (outlined)copy of the previous picturegenerated frame
This is a diagram, not app output. To check any slowed clip yourself, step through it one frame at a time (FrameSmoother's preview has buttons for that): if the same picture sits for several frames in a row (8 frames for a 30fps clip slowed 4x and saved at 60fps), nothing was generated.
02In numbers
A 4-second, 30fps clip at each setting
| Slow Motion | length | pictures / s if held | new frames per gap |
|---|---|---|---|
| Off | 4 s | 30 | 1 |
| 2x | 8 s | 15 | 3 |
| 4x | 16 s | 7.5 | 7 |
| 8x | 32 s | 3.75 | 15 |
With Target fps set to 60fps, the output plays at 60fps at every setting, and lengths are rounded. "Pictures / s if held" is what remains when frames are only repeated. Processing time grows roughly with the number of new frames.
03On the iPhone
Slowing a clip down in FrameSmoother
- Home
Tap Select Video and pick the clip. Choose a single video if you want to trim it.
- Interpolation Setup › Output Frame Rate
Keep Target fps and choose 60fps.
- Slow Motion
Pick 2x, 4x or 8x.
- Stabilization
If you shot the clip handheld, turn on Reduce camera shake. It is off until you turn it on.
- Trim
Move Start and End around the moment you want. Only that part is processed, which also cuts the processing time.
- top right › Queue
Tap Add to Queue. When the row says Completed, tap it: the preview runs the original at the matching slowed position, so both sides show the same moment. Back in the queue, save it with the download-arrow button on the row, or share it with the share button.
04More comparisons