Install

prec runs on Linux (x86_64), on Windows through WSL, and on macOS (Apple Silicon). Each release carries a Linux and a macOS binary with a SHA256SUMS file. There is no native Windows build: install the Linux binary inside WSL. On macOS the binary is built and its tests pass on GitHub’s runner; renders on a Mac are untested.

The binary

Linux and WSL:

v=$(basename "$(curl -fsSLo /dev/null -w '%{url_effective}' https://github.com/gmrdad82/prec/releases/latest)")
mkdir -p ~/.local/bin && curl -fsSL "https://github.com/gmrdad82/prec/releases/download/$v/prec-$v-linux-x86_64.tar.gz" | tar -xz -C ~/.local/bin prec

macOS (Apple Silicon):

v=$(basename "$(curl -fsSLo /dev/null -w '%{url_effective}' https://github.com/gmrdad82/prec/releases/latest)")
mkdir -p ~/.local/bin && curl -fsSL "https://github.com/gmrdad82/prec/releases/download/$v/prec-$v-macos-arm64.tar.gz" | tar -xz -C ~/.local/bin prec

~/.local/bin needs to be on your PATH. To check a download, fetch SHA256SUMS from the same release and run sha256sum -c --ignore-missing SHA256SUMS beside the .tar.gz.

From source, with Rust 1.97 or newer (replace vX.Y.Z with a release tag):

cargo install --locked --git https://github.com/gmrdad82/prec --tag vX.Y.Z prec

prec --version prints prec <x.y.z>.

Prerequisites

prec drives tools you install yourself:

Chromium or Google Chrome, run headless (chromium, chromium-browser, google-chrome-stable or google-chrome on the PATH, or chromium in the config).
ffmpeg and ffprobe with the libx264 encoder and the zscale filter (libzimg).
fontconfig (fc-match, fc-list), the default font JetBrainsMono Nerd Font (or pass --font), and a CJK font for wide characters.
git and bash.

On Debian or Ubuntu:

sudo apt install chromium ffmpeg fontconfig fonts-noto-cjk git

On Arch:

sudo pacman -S chromium ffmpeg fontconfig noto-fonts-cjk ttf-jetbrains-mono-nerd git

On macOS with Homebrew, then point chromium in the config at /Applications/Chromium.app/Contents/MacOS/Chromium:

brew install ffmpeg fontconfig git
brew install --cask chromium font-jetbrains-mono-nerd-font

The JetBrainsMono Nerd Font is also at nerdfonts.com.

Check the machine

prec doctor checks all of it and says what is missing. Here it is on an Arch Linux machine with everything in place and no config file (the home folder is shortened to ~):

$ prec doctor
ok   config                       ~/.config/prec/config.toml (absent; the defaults apply)
ok   ffmpeg                       /usr/bin/ffmpeg
ok   ffprobe                      /usr/bin/ffprobe
ok   fc-match                     /usr/bin/fc-match
ok   git                          /usr/bin/git
ok   chromium                     /usr/bin/chromium: Chromium 152.0.7977.82 Arch Linux
ok   xterm.js                     xterm.js 5.5.0, addon-canvas 0.7.0, addon-unicode11 0.8.0, embedded
ok   themes                       348 vendored from VHS v0.11.0
ok   ffmpeg encoder libx264       present
ok   archive root                 none configured; renders are never archived
ok   ffmpeg filter format         present
ok   ffmpeg filter blend          present
ok   ffmpeg filter concat         present
ok   ffmpeg filter zscale         present
ok   ffmpeg filter setparams      present
ok   default font                 JetBrainsMono Nerd Font (/usr/share/fonts/TTF/JetBrainsMonoNerdFont-Regular.ttf)
ok   CJK fallback                 WDXL Lubrifont TC,WDXL 滑油字 TC
opt  libfaketime (optional)       absent; apps pin their own clock through [env]
ok   cache                        ~/.cache/prec (270 B)

Start in 30 seconds

This repository carries a sample app, examples/demo, with three shots. Clone it and record one:

git clone https://github.com/gmrdad82/prec && cd prec
prec clip demo typing --app-dir examples/demo --size 720p --fps 30

recording demo typing in a 60x16 pty…
recorded 3.80s shown, 284 events → tmp/prec/run/demo-clip-typing-cast-338683/demo-clip-typing.cast
replaying demo typing: 114 frames at 1280x720@30…
archive: skipped (unconfigured)
tmp/renders/demo/clip/demo-clip-typing-1280x720-30fps.json

That writes tmp/renders/demo/clip/demo-clip-typing-1280x720-30fps.master.mp4, its poster PNG, the cast and the JSON manifest whose path it prints last. Record your first clip walks through each file, and Make a GIF turns the master into the clip below.

The clip that run makes: in a window on a dark ground, demo tick draws a progress bar, then demo show prints a truecolor gradient, a box with a wide CJK character, an arrow and blocks, and the 16 ANSI colours, before the clip crossfades back to its first frame.