---
title: "How to add a vertical blur background with Claude (tested prompt and ffmpeg command)"
description: "A wide 16:9 clip sits across the middle of a vertical frame, with a blurred copy of itself filling the top and bottom. Install one skill and ask Claude Code, or run the ffmpeg command we tested yourself."
url: https://www.recharm.com/effects/vertical-blur-background
---

# How to add a vertical blur background with Claude

A wide 16:9 clip sits across the middle of a vertical frame, with a blurred copy of itself filling the top and bottom.

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 vertical blur background to input.mp4
   Output size: 1080, 1920
   How blurred the background is: 24
   ```

## 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 vertical blur background 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                   |
| ------- | ------------ | ------------------------------ |
| `W, H`  | `1080, 1920` | Output size.                   |
| `BLUR`  | `24`         | How blurred the background is. |

## In other editors

From each editor’s own help pages, in our words. We haven’t run these ourselves.

Built in: **Canvas blur** · desktop

1. Import the video and drag it onto the timeline.
2. Resize the video, then click Video > Canvas.
3. Choose Blur (or Color or Pattern) to fill the empty space.
4. Adjust the style to match your project.

Source: [Change Video Canvas Background Effortlessly](https://www.capcut.com/tools/change-video-background) (CapCut), checked October 22, 2026.

## Without the skill

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

```
Turn the 16:9 clip input.mp4 into a 1080x1920 vertical video: the original sits in the middle at full width, and the space above and below is filled with a blurred, slightly darkened, zoomed-in copy of the same clip. Keep the audio. Use ffmpeg and save it as output.mp4.
```

## Run it without Claude

This is the exact command we tested. Save it as `vertical-blur-background.sh` and run:

```
sh vertical-blur-background.sh input.mp4 output.mp4
```

```
#!/bin/sh
# Vertical blur background: fit a 16:9 clip into a 9:16 frame, filling the empty space with a blurred, zoomed copy of itself.
# Usage: sh vertical-blur-background.sh input.mp4 output.mp4
set -e
IN="$1"; OUT="$2"
W=1080; H=1920   # output size (9:16)
BLUR=24          # background blur radius

ffmpeg -y -i "$IN" -filter_complex "\
[0:v]split[a][b];\
[a]scale=$W:$H:force_original_aspect_ratio=increase,crop=$W:$H,boxblur=$BLUR:2,eq=brightness=-0.06[bg];\
[b]scale=$W:-2[fg];\
[bg][fg]overlay=(W-w)/2:(H-h)/2,setsar=1,format=yuv420p[v]" \
  -map "[v]" -map "0:a?" -c:v libx264 -crf 18 -c:a copy "$OUT"
```

## More layouts and reframing

- [Background replacement **Background replacement**](https://www.recharm.com/effects/background-replacement)
- [Binocular view **Binocular view**](https://www.recharm.com/effects/binocular-view)
- [Blur region **Blur region**](https://www.recharm.com/effects/blur-region)
- [Cinematic bars **Cinematic bars**](https://www.recharm.com/effects/cinematic-bars)
- [Comic panel layout **Comic panel layout**](https://www.recharm.com/effects/comic-panel-layout)

## 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)