prec

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

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. From source, with Rust 1.97 or newer: cargo install --locked --git https://github.com/gmrdad82/prec --tag v1.5.1 prec. On macOS the binary is built on an Apple Silicon Mac; renders on a Mac are untested.

What it drives

# Debian or Ubuntu
sudo apt install chromium fontconfig fonts-noto-cjk git
# Arch
sudo pacman -S chromium fontconfig noto-fonts-cjk ttf-jetbrains-mono-nerd git
# macOS with Homebrew
brew install fontconfig git
brew install --cask chromium font-jetbrains-mono-nerd-font

Your first clip in 30 seconds

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

That records the repository's sample app from its tape and writes the master MP4, its poster PNG, the cast and a JSON manifest under tmp/renders/demo/clip/. Turn the master into a GIF with pcod from pito-codecs: pcod <master> demo.gif --size 1280 --fps 15.

In your app's repository

prec shots myapp
prec clip  myapp tour --size 1080p --fps 60
prec still myapp palette --size 2160p --derive 1080p --web 800
prec clip  myapp tour --rev v1.4.0 --themes "Catppuccin Latte,Catppuccin Mocha"
prec render tmp/renders/myapp/clip/myapp-clip-tour-1920x1080-60fps.cast --size 720p --fps 30

app = "myapp"
bin = "myapp"
grid = [120, 34]
frame = "bare"
setup = "{bin}/myapp-fixture >/dev/null"
teardown = "myapp server --stop || true"

[build]
command = "cargo build --release --locked --bin myapp --bin myapp-fixture"
bin_dir = "{target}/release"

[env]
MYAPP_DATA = "{scratch}/data"
MYAPP_NOW = "2026-09-29T10:00:00Z"

[theme]
background = "#eff1f5"
foreground = "#4c4f69"

[shots.tour]
kind = "clip"
line = "The terminal workspace stepping through its views"
tape = "render/terminal/tour.tape"
launch = "myapp tui"
settle = "3s"
closure = "palindrome"

1. 01

   Every frame, at the rate you ask for

   prec doesn't capture the screen while the app runs. It records the app's output bytes with their timestamps, then steps a virtual clock at exactly 1/fps and draws each frame, so a clip has the shown time times the fps in frames, however heavy the frame or the rate.

   A clip is one silent H.264 master (CRF 14, BT.709 limited range, tagged), a poster PNG and a JSON manifest with each file's sha256.

   More on replay

2. 02

   Wait for the screen, not the clock

   A tape holds only steps: text to type and keys to press, such as Enter, Tab, Shift+Tab, Esc, , PgUp, Ctrl+C or Alt+Enter, each with an optional delay and repeat count.

   Wait /ready/ returns as soon as the screen matches, and Idle 3s once the screen, colours and cursor included, has stayed the same for 3 seconds, as when an agent session finishes. The size, theme and font live in the app's config, so one tape renders at any of them.

   More on tapes

   Sleep 300ms
   Type "demo tick"
   Enter
   Sleep 1.6s
   Type "demo show"
   Enter
   Sleep 1.2s

   Type@0ms "myapp tui"
   Enter
   Wait /ready/
   Down@200ms 3
   Enter
   Ctrl+C

3. 03

   Native pixels at every size

   The grid is fixed and the font is fitted to each size, so 4K shows exactly what 720p shows, drawn at its own pixels rather than scaled.

   xterm.js 5.5 with Unicode 11 widths draws truecolor, box drawing, wide CJK and Nerd Font glyphs.

   

4. 04

   348 themes, light and dark from one recording

   The app's own palette, any of VHS's 348 built-in schemes, curated light and dark pairs, and your installed Omarchy themes. --themes renders one recording in several at once.

   More on render many

   

5. 05

   A window, or the app to the edges

   --frame window draws a window with its bar and shadow on a ground; --frame bare leaves the app's own ground to the edges, for a TUI that fills its terminal.

   

6. 06

   Your data stays out of the picture

   The pty starts from a clean environment with a scratch HOME. pass_env hands named variables to the app, and the cast lists the names, never the values. On Linux, home runs the session in its own namespace with the home and hostname you choose.

   Before a replay, prec reads the screen the cast shows and refuses a picture with your home path, hostname, user name, an email or a passed value, one line per finding at its shown second. Masks fill a regex match or a block of cells in every frame.

   Record, replay, encode

   • Record. The app runs in a pty of exactly the grid, driven by the tape at real speed, kept as an asciicast v2 cast.
   • Replay. A vendored xterm.js in headless Chromium, started with a scratch home, TZ=UTC and C.UTF-8, so your locale and fontconfig never reach it.
   • Encode. Fixed encoder threads, so a master is byte-identical on any machine; prec reads the MP4 back and checks its frame count before the manifest claims it.
   • Atomic. A failed or cancelled re-render never leaves new files beside an old manifest.

• pitomd.com

  Splicer's guide shots

  The terminal shots in Splicer's guides on this site are recorded by prec, from Splicer's released binary and a tape.

  See Splicer
• Open source

  The clips on these pages

  prec recorded the terminal clips of pito-codecs, pito-compare and pito-tui shown on their pages, each from that repository's own shot.

  See pito-tui's
• pito-codecs

  Masters with no ffmpeg

  Its masters are encoded inside prec by pito-codecs, and pcod turns them into GIFs, WebP and web MP4s.

  See pito-codecs