A Codex skill for turning local videos into short clips with 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. No OpenAI API key required.

• 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

Recommended install with local captions:

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

This installs:

• the Codex skill
• whisper.cpp for local transcription, if missing
• Pillow for burned-in captions, if missing
• the default local Whisper model tiny.en

Base install without captions:

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

This installs the skill into:

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

Then restart Codex so it can discover the skill.

English captions work with the default install:

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

For Italian or other languages, install the multilingual model:

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

This downloads ggml-base.bin, which supports language codes such as it, en, and auto.

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.

Italian captions:

Use $video-short-maker to create a 30s vertical high quality short with Italian 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.

Softer cuts:

Use $video-short-maker to create a 30s vertical short from /Users/me/Desktop/demo.mp4 using light cut style.

More aggressive cuts:

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

Vertical 9:16 for Shorts/Reels/TikTok:

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

Original aspect ratio:

Use $video-short-maker to create a 30s short from /Users/me/Desktop/demo.mp4.

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

• *.short.mp4: edited short
• *.srt: generated subtitles, when captions are used
• *.captioned.mp4: final video with burned-in captions
• *.report.json: edit report with selected segments and settings

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

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.

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

Base video cutting only requires ffmpeg.

If captions setup fails, install dependencies manually:

brew install ffmpeg whisper-cpp
python3 -m pip install --user Pillow

Then reinstall:

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

If Codex does not recognize $video-short-maker, restart Codex after installing.

Check that the skill exists:

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

You should see:

SKILL.md
agents/
scripts/

MIT