cast-studio 0.1.3

Convert asciinema .cast files to GIF and MP4, with a generic demo-recording engine

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🎬 cast-studio

Convert asciinema .cast recordings into GIF and MP4 — and scaffold a generic demo-recording engine for any Python project.

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📦 Installation

uv add cast-studio

System requirement: ffmpeg must be installed.

brew install ffmpeg        # macOS
apt-get install ffmpeg     # Ubuntu / Debian

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🚀 Features

• ✅ cast → GIF — High-quality 256-colour GIF via ffmpeg palette pass
• ✅ cast → MP4 — H.264/x264 CRF-18 MP4 ready for GitHub Releases
• ✅ Catppuccin Mocha theme — Beautiful dark terminal rendering with Pillow
• ✅ Generic demo engine — cast-run + demo.cfg for any project
• ✅ Any shell command — Record pytest runs, scripts, CLIs — not just pytest
• ✅ Multi-line descriptions — Pipe-separated description lines per run
• ✅ python-base-command CLI — Structured, loggable CLI with cast / cast-render / cast-init

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⚙️ Configuration

No .env needed. All config lives in demo.cfg:

PROJECT="my-library"
SUBTITLE="A short description"
INSTALL_CMD="pip install my-library"
REPO_URL="github.com/you/my-library"
PYPI_URL="pypi.org/project/my-library"

PYTEST=".venv/bin/pytest"
TESTS="tests/"

PAUSE_INTRO=2       # seconds after intro screen
PAUSE_BETWEEN=2     # seconds between runs
PAUSE_OUTRO=3       # seconds on outro screen

define_runs() {
  add_run "RUN 1 — feature A" "Short description." "$PYTEST $TESTS --flag"
  add_run "RUN 2 — script"   "Another feature."    "python scripts/my_script.py"
}

add_run "Title" "Line 1|Line 2" "any shell command" — use | for multi-line descriptions.

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🛠️ How to Use

1. Install — uv add cast-studio (and brew install ffmpeg asciinema)
2. Create .cfg — customise demo.cfg with your project's runs
3. Record — asciinema rec -c "cast-run demo/demo.cfg" demo.cast
4. Render — cast-render demo.cast assets/demo --gif-only --title "my demo" → assets/demo.gif
5. Embed — add ![demo](assets/demo.gif) to your README

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🚀 Quick Start

# 1. Install
uv add cast-studio
brew install ffmpeg asciinema   # macOS

# 2. Create demo/demo.cfg — set PROJECT, SUBTITLE, INSTALL_CMD, define_runs()

demo/demo.cfg structure:

# ── project metadata ──────────────────────────────────────────────────────────
PROJECT="cast-studio"
SUBTITLE="Convert asciinema .cast files to GIF and MP4"
INSTALL_CMD="uv add cast-studio"
REPO_URL="github.com/aviz92/cast-studio"
PYPI_URL="pypi.org/project/cast-studio"

# ── timing (seconds) ─────────────────────────────────────────────────────────
PAUSE_INTRO=2
PAUSE_BETWEEN=2
PAUSE_OUTRO=3

# ── runs ──────────────────────────────────────────────────────────────────────
define_runs() {
  add_run \
    "STEP 1 — cast-init  │  scaffold demo scripts into your project" \
    "Creates run_demo.sh (the engine) and demo.cfg (your project config).|One command sets up the full demo recording workflow." \
    "cast-init --dest /tmp/cast-studio-demo --force"

  add_run \
    "STEP 2 — demo.cfg  │  inspect the generated config" \
    "Edit PROJECT, SUBTITLE, INSTALL_CMD, and define_runs().|Add any shell command — pytest, scripts, CLIs — using add_run." \
    "cat /tmp/cast-studio-demo/demo.cfg"

  add_run \
    "STEP 3 — cast-render  │  render a .cast file to GIF" \
    "Renders each frame as a PNG using Pillow (Catppuccin Mocha theme).|Then encodes a high-quality 256-colour GIF via ffmpeg palette pass." \
    "cast-render demo.cast assets/demo --gif-only --title \"cast-studio demo\""

  add_run \
    "STEP 4 — cast-render  │  render to MP4" \
    "H.264/x264 CRF-18 encode — ready for GitHub Releases or Twitter.|Use --hold to extend the last frame so viewers can read the outro." \
    "cast-render demo.cast assets/demo --mp4-only --hold 5.0 --title \"cast-studio demo\""

  add_run \
    "STEP 5 — cast  │  unified runner" \
    "The cast command auto-discovers all sub-commands.|cast render / cast init / cast --help — one entry point for everything." \
    "cast --help"
}

# 3. Record
asciinema rec -c "bash cast-run demo/demo.cfg" assets/demo/demo.cast

# 4. Render to GIF and MP4
cast-render assets/demo/demo.cast assets/demo/demo --gif-only --title "my-library demo"  # -> `assets/demo/demo.gif`
cast-render assets/demo/demo.cast assets/demo/demo --mp4-only --title "my-library demo"  # -> `assets/demo/demo.mp4`

# 5. Embed in README
# ![demo](assets/demo.gif)

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🎥 Demo

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CLI Reference

cast-render

Flag	Default	Description
cast_file	—	Path to .cast file
output_base	—	Output path without extension
--title	""	Title bar text
--gif-only	—	Produce GIF only
--mp4-only	—	Produce MP4 only
--render-fps	30	Internal PNG frame rate
--gif-fps	10	GIF output FPS
--mp4-fps	30	MP4 output FPS
--hold	3.0	Seconds to hold last frame
--keep-frames	—	Keep temporary PNG frames

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🤝 Contributing

If you have a helpful pattern or improvement to suggest: Fork the repo Create a new branch Submit a pull request I welcome additions that promote clean, productive, and maintainable development.

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📄 License

MIT License — see LICENSE for details.

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🙏 Thanks

Thanks for exploring this repository!
Happy coding!