MultiHUD

MultiHUD is a macOS app that adds live data to a virtual camera feed. It is inspired by PedalHUD.

What it does

• Creates a virtual camera through a CoreMediaIO system extension. You can select it in Zoom, Meet, Teams, and similar apps.
• Combines your webcam feed with live data overlays.
• Widget overlays: pills on the video stream. You can set the position of each widget.
  • Weather: shows the current temperature and conditions from WeatherKit. It remains visible after a video app replaces the background.
  • Clock: shows the current time and time-zone abbreviation.
  • Meeting timer: a count-up timer. Start or reset it from the host app or menu bar.
  • Countdown: counts down to a clock time that you set. It shows overdue time in red after the target time.
• Virtual background: select a JPEG, PNG, HEIC, or another image. The extension separates you from the background with Robust Video Matting or Vision, then places you over the image.
• Blur background: blurs your real background without a custom image.
• Dynamic resolution: change between 720p and 1080p without reinstalling the extension.
• Overlay safe areas: Full Frame, Meeting Safe, Top Strip, and Lower Third profiles keep widgets visible when video apps crop the feed.
• Camera source selection: select a physical camera when more than one camera is available.
• Menu bar extra: change widget settings and opacity without opening the main window.
• Auto-launch: starts the host app when a video app activates the virtual camera.
• Single host instance: prevents a Debug launch, URL wake, or second launch from starting two host apps.

Requirements

• macOS 15.0 or later
• An Apple Developer account with the WeatherKit and System Extension capabilities for net.fakeapps.MultiHUD

Build and run

cd MultiHUD
xcodegen generate
xcodebuild -scheme MultiHUD -configuration Debug -allowProvisioningUpdates build
cp -R ~/Library/Developer/Xcode/DerivedData/MultiHUD-*/Build/Products/Debug/MultiHUD.app /Applications/
open /Applications/MultiHUD.app

Run the app from /Applications. System extensions need this location.

Deploy a release build

cd MultiHUD
bash scripts/deploy.sh

The script builds the Release version and verifies its signature. It notarizes and staples the app, installs it in /Applications, and starts it. It uses the MultiHUD keychain profile with xcrun notarytool. Fork maintainers must change the keychain profile name and signing identity in scripts/deploy.sh.

Releases

A v* tag starts a GitHub Actions workflow. The workflow builds, signs, notarizes, and publishes a .dmg on the Releases page. Configure these repository secrets:

Secret	Description
BUILD_CERTIFICATE_BASE64	Base64-encoded Developer ID Application certificate (.p12)
P12_PASSWORD	Password for the .p12 file
KEYCHAIN_PASSWORD	Password for the temporary build keychain
MAIN_PROFILE_BASE64	Base64-encoded provisioning profile for net.fakeapps.MultiHUD
EXTENSION_PROFILE_BASE64	Base64-encoded provisioning profile for net.fakeapps.MultiHUD.CameraExtension
APPLE_ID	Apple ID for notarization
APPLE_ID_PASSWORD	App-specific password for the Apple ID

Architecture

project.yml defines two targets. XcodeGen manages the project.

Target	Bundle ID	Role
MultiHUD	net.fakeapps.MultiHUD	SwiftUI host app that installs the extension and gets weather data
CameraExtension	net.fakeapps.MultiHUD.CameraExtension	CoreMediaIO system extension that captures the webcam and renders overlays

The host app gets weather data from WeatherKit. It writes the data to the shared app group container. The extension reads these files for the overlay. The extension makes no network calls.

Shared container files

File	Written by	Read by	Purpose
weather.txt	Host app	Extension	Current temperature and weather symbol (tempC|tempF|symbolName)
background.jpg	Host app	Extension	Virtual background image
settings.json	Host app	Extension	Other configuration values, shown below

settings.json schema

{
  "cameraId":       "",
  "blurBackground": false,
  "segQuality":     "fast",
  "resolution":     "720p",
  "opacity":        1.0,
  "overlaySafeArea": "fullFrame",
  "useRVM":         true,
  "widgets": [
    { "type": "weather",   "position": "bottomLeft",  "enabled": true  },
    { "type": "clock",     "position": "bottomLeft",  "enabled": false },
    { "type": "countup",   "position": "bottomRight", "enabled": false, "startedAt": 0.0 },
    { "type": "countdown", "position": "bottomLeft",  "enabled": false, "endsAt": 0.0 }
  ]
}

• position: bottomLeft · bottomCenter · bottomRight · topLeft · topCenter · topRight
• overlaySafeArea: fullFrame · meetingSafe · topStrip · lowerThird
• useRVM: uses the bundled Robust Video Matting model when true. It uses Apple Vision person segmentation when false.
• Widgets at the same position appear in one pill. Widgets at different positions appear in separate pills.
• startedAt and endsAt: Unix timestamps. A value of 0 hides the widget because its timer is not running.

Tech stack

• Swift and SwiftUI for macOS 15.0 or later
• CoreMediaIO and CMIOExtension for the virtual camera
• WeatherKit and CoreLocation
• AVFoundation for webcam capture
• CoreML and Vision for person segmentation. Robust Video Matting uses the Neural Engine. Vision is the fallback.
• CoreImage, CIFilter, and Metal for compositing. A guided image filter improves edge detail.