---
title: "How to add a color bars test pattern with Claude (tested prompt and ffmpeg command)"
description: "Seven vertical TV test bars, from gray and yellow through cyan, green, magenta and red to blue, hold the screen for 1.5 seconds over a steady beep, then hard cut to the clip. Install one skill and ask Claude Code, or run the ffmpeg command we tested yourself."
url: https://www.recharm.com/effects/color-bars-test-pattern
---

# How to add a color bars test pattern with Claude

Seven vertical TV test bars, from gray and yellow through cyan, green, magenta and red to blue, hold the screen for 1.5 seconds over a steady beep, then hard cut to the clip.

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 color bars test pattern to input.mp4
   Seconds of color bars before the clip: 1.5
   Pitch of the test tone in Hz: 1000
   ```

## 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 color bars test pattern 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                           |
| -------- | ------- | -------------------------------------- |
| `BARS`   | `1.5`   | Seconds of color bars before the clip. |
| `TONE`   | `1000`  | Pitch of the test tone in Hz.          |
| `VOLUME` | `0.2`   | Loudness of the tone, 0 to 1.          |

## Without the skill

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

```
Put a 1.5 second SMPTE color bars leader in front of input.mp4: 1.5 seconds of standard SMPTE color bars at the clip's full size (ffmpeg's smptebars source; seven 75% bars across the top two thirds: gray, yellow, cyan, green, magenta, red, blue, left to right) with a steady 1000 Hz sine tone at volume 0.2, then a hard cut to the clip, which plays in full from its first frame with its own audio. The output is 7.5 seconds, 30fps. Use ffmpeg, keep the audio, and save it as output.mp4 (H.264, yuv420p).
```

## Run it without Claude

This is the exact command we tested. Save it as `color-bars-test-pattern.sh` and run:

```
sh color-bars-test-pattern.sh input.mp4 output.mp4
```

```
#!/bin/sh
# Color bars test pattern: 1.5 seconds of SMPTE color bars with a steady 1 kHz tone, then a hard cut to the clip.
# Usage: sh color-bars-test-pattern.sh input.mp4 output.mp4  (the input needs an audio track)
set -e
IN="$1"; OUT="$2"
BARS=1.5    # seconds of color bars before the clip
TONE=1000   # pitch of the test tone in Hz
VOLUME=0.2  # loudness of the tone (0-1)

SIZE=$(ffprobe -v error -select_streams v:0 -show_entries stream=width,height -of csv=s=x:p=0 "$IN")
RATE=$(ffprobe -v error -select_streams a:0 -show_entries stream=sample_rate -of csv=p=0 "$IN")
# the bars and tone are made at the clip's size and sample rate so concat can join them to it
ffmpeg -y -i "$IN" -f lavfi -i "smptebars=s=$SIZE:r=30:d=$BARS" \
  -f lavfi -i "sine=frequency=$TONE:sample_rate=$RATE:duration=$BARS" -filter_complex "\
[1:v]format=yuv420p,setsar=1[bars];\
[2:a]volume=$VOLUME,aformat=channel_layouts=stereo[tone];\
[0:v]fps=30,format=yuv420p,setsar=1[clip];\
[0:a]aformat=channel_layouts=stereo[sound];\
[bars][tone][clip][sound]concat=n=2:v=1:a=1[v][a]" \
  -map "[v]" -map "[a]" -c:v libx264 -crf 18 -pix_fmt yuv420p -c:a aac "$OUT"
```

## More retro and film

- [1950s color film look **1950s color film look**](https://www.recharm.com/effects/1950s-color-film-look)
- [35mm film look **35mm film look**](https://www.recharm.com/effects/35mm-film-look)
- [70s film look **70s film look**](https://www.recharm.com/effects/70s-film-look)
- [Camcorder date stamp **Camcorder date stamp**](https://www.recharm.com/effects/camcorder-date-stamp)
- [Camcorder viewfinder **Camcorder viewfinder**](https://www.recharm.com/effects/camcorder-viewfinder)

## Find 3x _winning ads_

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