Codex Video Short Maker Skill

A Codex skill for turning local videos into short clips with optional local captions.

Give Codex a local video and it can remove dead air, cut pauses, export a vertical short, generate local Whisper subtitles, and burn captions into the final MP4.

What It Does

• Turns local videos into 30-60s shorts
• Removes dead air and boring pauses
• Supports light, normal, and aggressive cut styles
• Exports vertical 9:16 MP4 for Shorts/Reels/TikTok
• Exports high quality H.264 MP4
• Optionally generates local captions with whisper.cpp
• No OpenAI API key required

Installation

Base install:

npx --yes codex-video-short-maker-skill@latest

Full install with local captions:

npx --yes codex-video-short-maker-skill@latest --with-captions

This installs the skill into:

~/.codex/skills/video-short-maker

Then restart Codex so it can discover the skill.

Captions Setup

Captions are optional. If you install with:

npx --yes codex-video-short-maker-skill@latest --with-captions

the installer will:

• copy the skill into Codex
• install whisper.cpp with Homebrew if missing
• install Pillow if missing
• download the default local Whisper model tiny.en

For multilingual captions, install a multilingual model:

npx --yes codex-video-short-maker-skill@latest --with-captions --caption-model base

Usage

After installation, restart Codex and run:

Use $video-short-maker to create a 30s vertical high quality short with English captions from /Users/me/Desktop/demo.mp4 using aggressive cut style.

Without captions:

Use $video-short-maker to create a 45s vertical short from /Users/me/Desktop/demo.mp4.

Italian captions:

Use $video-short-maker to create a 30s vertical high quality short with Italian captions from /Users/me/Desktop/demo.mp4.

Output

The skill creates files next to the input video:

demo.vertical.short.mp4
demo.vertical.short.srt
demo.vertical.short.captioned.mp4
demo.vertical.short.report.json

Cut Styles

• light: softer cuts, preserves more pauses
• normal: balanced default
• aggressive: removes more pauses and dead air

Manual Installation

Clone the repository:

git clone https://github.com/Kappaemme-git/codex-video-short-maker-skill.git

Copy the skill into your Codex skills directory:

mkdir -p ~/.codex/skills
cp -R codex-video-short-maker-skill/video-short-maker ~/.codex/skills/video-short-maker

Restart Codex.

Requirements

• ffmpeg and ffprobe
• macOS + Homebrew for automatic local captions setup
• whisper.cpp for captions
• Pillow for burned-in captions

Base video cutting only requires ffmpeg.

License

MIT