You want to record a talking-head video over a couple of screens. So you wrangle OBS scenes, or you screen-record one display and forget the second, and then you spend the evening nudging clips around a timeline trying to line up audio.

justroll is a single terminal command. It opens a wizard, you pick your mic and which screens and camera to capture, and it records each source to its own file - all carrying a copy of the same microphone, so your editor snaps them into sync automatically.

• One file per source — every screen and the camera record independently, hardware-encoded. Nothing is composited, so you cut them however you want.
• Sync without a clapperboard — the same mic is muxed into every clip, so any editor's "synchronize by audio" lines them up. No timecode gear.
• Honest about macOS — it groups screens into one ffmpeg process (concurrent screen captures deadlock otherwise), and the wizard tells you up front when a mic is silent, a display is locked, or a permission is missing.

Quick Start

$ brew install ffmpeg          # the only dependency
$ npm install -g justroll

$ justroll "Tutorial Take 1"   # opens the wizard: pick mic, cameras, screens
# ...record. watch the live waveform. press Ctrl+C (or q) to stop & finalize...

$ ls ~/Recordings/2026-06-01_tutorial-take-1/raw
camera.mkv   camera.mp4   screen-0.mkv   screen-0.mp4   screen-1.mkv   screen-1.mp4

Install

npm (requires macOS, Node 20+, and ffmpeg):

brew install ffmpeg
npm install -g justroll

From source:

git clone https://github.com/kunchenguid/justroll
cd justroll
pnpm install
pnpm link --global   # puts `justroll` on your PATH

First run will trigger macOS prompts for Screen Recording, Camera, and Microphone. Screen Recording in particular must be granted to your terminal in System Settings → Privacy & Security, then the terminal restarted.

How It Works

  justroll "title"
        │
        ▼
  ┌───────────────┐   pick mic, cameras, screens
  │    wizard     │   live mic meter + readiness checks
  └───────┬───────┘
          │ start
          ▼
  ┌───────────────────────────────┐      ┌──────────────┐
  │  all screens → ONE ffmpeg proc │      │  audio tap   │
  │  each camera → its own proc    │ ───► │  live wave   │
  │  (same mic muxed into each)    │      └──────────────┘
  └───────┬───────────────────────┘
          │ Ctrl+C / q  →  clean finalize
          ▼
  raw/screen-0.mkv  raw/camera.mkv  ...  (+ .mp4, session.json, notes.md)
          │
          ▼
  import the folder → your editor's sync-by-audio aligns every clip

• Screens share a process. macOS hangs when two avfoundation screen-capture processes run at once, so justroll records all screens from a single ffmpeg with one mapped output per screen. Cameras stay separate, so a dead capture-card can't stall the screens.
• Crash-safe, then convenient. It records to MKV (survives an abrupt kill) and remuxes to MP4 after you stop. Toggle the remux in the review screen.
• VideoToolbox encoding. h264_videotoolbox keeps capture light on CPU.
• It tells you when something's wrong. A live mic meter, empty-device guidance, low-disk/permission warnings, and per-source no frames / dropped flags during recording - no separate "doctor" command.

CLI Reference

| Command | Description | | --------------------- | ------------------------------------------------------- | | justroll "title" | Start the recording wizard | | justroll --selftest | Headless capture that verifies the full pipeline | | justroll --demo | Live UI preview with a synthetic engine (records nothing) | | justroll --help | Show help | | justroll --version | Print the version |

Flags

| Command | Flag | Description | | ------------- | ---------------- | ---------------------------------------- | | justroll | --dir <path> | Override the recordings directory | | justroll | --no-mp4 | Keep MKV only (skip the mp4 remux) | | justroll | --fps <n> | Capture frame rate (24/30/48/60) | | --selftest | --seconds <n> | Capture duration for the self-test |

In the wizard: ↑↓ move, space toggle a camera/screen, ←→ change a setting, enter advance/start, esc back, q quit. While recording: Ctrl+C stop & review, q stop & quit.

Configuration

Optional, at ~/.config/justroll/config.json (defaults shown):

{
  "recordingsDir": "~/Recordings",
  "video": { "fps": 30, "codec": "h264_videotoolbox", "container": "mkv", "pixelFormat": "nv12" },
  "remuxToMp4": true,
  "defaults": { "mic": "RODE NT-USB", "embedMicInEveryFile": true }
}

Development

pnpm test            # unit + UI tests (node:test + ink-testing-library)
pnpm run lint        # eslint
pnpm run format      # prettier --write
pnpm run demo        # live UI preview, records nothing
pnpm run selftest    # headless pipeline check against your real devices
make demo            # regenerate demo.gif + demo.mp4 (needs vhs + ffmpeg)

Telemetry

justroll sends anonymous usage counts to my self-hosted analytics so I can see what's actually getting used - number of screens/cameras, fps, duration. No titles, device names, or file paths are ever sent. Set JUSTROLL_TELEMETRY=0 to turn it off.