tally

README

Tally

A macOS menu bar app that turns on a smart light outside your office when your camera is in use, so the household knows you're in a meeting. Named for the tally light — the red lamp on a studio camera that tells everyone it's live.

• An ON AIR sign lives in your menu bar — lit red when you're live, dark when you're not
• When any app (Zoom, Google Meet, FaceTime, ...) turns on your camera, your light turns red; when the camera turns off, the light turns off
• Click the sign to override the status — Force On Air or Force Off Air for 5 minutes, 1 hour, or until you turn it off
• Pick which light this computer controls from the same menu (scans your network for bulbs)
• Optional Start at Login

Built with menuet.

How it works

Camera detection uses CoreMediaIO's kCMIODevicePropertyDeviceIsRunningSomewhere property, which reports whether any process has a capture device open — no log parsing, no per-app integration, and it doesn't require camera permission. Change notifications come from CMIO property listeners, with a low-frequency poll as a safety net.

Wiz bulbs are controlled over their local UDP protocol (JSON on port 38899, no hub, no cloud, no auth). Bulbs are discovered with a broadcast probe and identified by MAC address, so the app finds the bulb again if DHCP hands it a new IP.

While you're in a meeting the app re-asserts the red state once a minute, so the light recovers from power blips. When you're not in a meeting it leaves the bulb alone (after turning it off once), so the bulb can still be used as a normal light.

Building

Requires macOS and Go.

make run

builds Tally.app and launches it. go run . also works for quick iteration, but Start at Login wants a real bundle path, so prefer the app bundle for daily use.

Adding other brands of light

pkg/light defines the provider interface:

type Provider interface {
    Name() string
    Discover(ctx context.Context) ([]light.Config, error)
    Connect(cfg light.Config) (light.Light, error)
}

pkg/light/wiz is the reference implementation. A new brand (LIFX is the next obvious one — it has a similar local UDP protocol) just implements Provider, calls light.Register in its init, and gets a blank import in main.go; discovered lights from every provider show up together in the menu. Light identity (Config.ID) should be something stable like a MAC address, not an IP.

A future idea is to associate the selected light with the current Wi-Fi network, so a laptop can control different lights at home and at the office. Config is persisted as JSON with that kind of extension in mind.

Documentation

Overview

Tally is a macOS menu bar app that turns on a smart light outside your office when your camera is in use, so the household knows you're on the air. The menu bar shows an ON AIR sign — lit red when live, dark when not; click it to override the status or pick which light to control.