---
title: "How to add a smooth slow motion with Claude (tested prompt and ffmpeg command)"
description: "The first three seconds of the orbit around the bottle stretch over six at half speed, with every other frame a newly built in-between, so the camera glides instead of stuttering. Install one skill and ask Claude Code, or run the ffmpeg command we tested yourself."
url: https://www.recharm.com/effects/smooth-slow-motion
---

# How to add a smooth slow motion with Claude

The first three seconds of the orbit around the bottle stretch over six at half speed, with every other frame a newly built in-between, so the camera glides instead of stuttering.

Made by the command on this page, from our own test clip.

## Get this effect

1. ### Switch to Code in your [Claude Desktop App](https://claude.com/download)

2. ### Install the skill (once)

   ```
   Install the Recharm video effects skill: download https://recharm-growth-staging.s3.us-east-2.amazonaws.com/website/downloads/recharm-video-effects.zip and unzip it into ~/.claude/skills
   ```

3. ### Ask for the effect

   ```
   Add a smooth slow motion to input.mp4
   Playback speed: 0.5
   Seconds of output to keep: 6
   ```

## Several videos, several effects, one ask

Put your clips in the folder, mention them with @, and ask for everything at once. Claude runs one tested script after another on each clip, then joins them.

Add a smooth slow motion to **@clip1.mp4**, put a sale badge on **@clip2.mp4**, give **@clip3.mp4** a VHS look, then join all three with crossfades.

## Settings you can change

Ask Claude to change any of these, or edit them at the top of the command.

| Setting  | Default | What it does                                                                                                  |
| -------- | ------- | ------------------------------------------------------------------------------------------------------------- |
| `SPEED`  | `0.5`   | Playback speed. 0.5 is half speed, so the first 3 seconds of the input fill 6 seconds; 0.25 is quarter speed. |
| `LENGTH` | `6`     | Seconds of output to keep.                                                                                    |
| `FPS`    | `30`    | Output frame rate. The frames the slow-down leaves missing are interpolated from the motion.                  |

## Without the skill

Don’t want to install the skill? Paste this prompt into Claude Code and Claude writes the command itself.

```
Turn input.mp4 (540x960, 30fps, 6 seconds) into smooth slow motion at half speed (0.5x): output time t shows input time t / 2 (output 1.0s = input 0.5s, 3.0s = 1.5s, 5.5s = 2.75s), so the first 3 seconds of the input fill a 6-second output. Don't repeat frames: build the in-between frames with motion-compensated frame interpolation (ffmpeg setpts=PTS/0.5 then minterpolate=fps=30:mi_mode=mci:mc_mode=aobmc:me_mode=bidir:vsbmc=1), so every output frame at 30fps differs from the one before. Don't crop, zoom or add anything to the picture, and don't add any text. Keep the input's audio playing at normal speed, cut to 6 seconds. Keep the size and 30fps frame rate, and save it as output.mp4.
```

## Run it without Claude

This is the exact command we tested. Save it as `smooth-slow-motion.sh` and run:

```
sh smooth-slow-motion.sh input.mp4 output.mp4
```

```
#!/bin/sh
# Smooth slow motion: play the shot at half speed, building the missing in-between frames from the motion.
# Usage: sh smooth-slow-motion.sh input.mp4 output.mp4
# Needs ffmpeg (its minterpolate filter does the frame interpolation).
set -e
IN="$1"; OUT="$2"
SPEED=0.5   # playback speed (0.5 = half speed: the first 3 seconds of the input fill 6 seconds)
LENGTH=6    # seconds of output to keep
FPS=30      # output frame rate; at 0.5x every other frame is a new, interpolated one

ffmpeg -y -i "$IN" -filter_complex \
  "[0:v]setpts=PTS/$SPEED,minterpolate=fps=$FPS:mi_mode=mci:mc_mode=aobmc:me_mode=bidir:vsbmc=1[v]" \
  -map "[v]" -map 0:a? -t "$LENGTH" -c:v libx264 -crf 18 -pix_fmt yuv420p -c:a aac "$OUT"
```

## More motion and camera

- [2.5D parallax photo **2.5D parallax photo**](https://www.recharm.com/effects/2-5d-parallax-photo)
- [Back-and-forth loop **Back-and-forth loop**](https://www.recharm.com/effects/back-and-forth-loop)
- [Background blur **Background blur**](https://www.recharm.com/effects/background-blur)
- [Bullet time **Bullet time**](https://www.recharm.com/effects/bullet-time)
- [Cinemagraph **Cinemagraph**](https://www.recharm.com/effects/cinemagraph)

## Find 3x _winning ads_

Recharm cuts your ad footage into tagged, searchable clips: hooks, testimonials, product shots. Find the shots that win, add the effect with Claude, and ship 3x more ad edits.

[Start 14-day free trial](https://www.recharm.com/get-started)