Ai/AudioVUMeter

Audio VU Meter for macOS

A native macOS SwiftUI application that displays real-time audio levels from BlackHole (or any audio input device) as a classic VU meter, along with system resource monitoring.

Features

Audio VU Meter

• Real-time audio level monitoring - Displays Left and Right channel levels
• dB scale display - Shows audio levels in decibels (-60 dB to 0 dB)
• Peak hold indicators - Visual peak markers with configurable hold time
• BlackHole integration - Automatically detects and selects BlackHole virtual audio device
• Multi-device support - Switch between any available audio input device

System Resource Monitors

• CPU Usage - Real-time CPU utilization percentage
• RAM Usage - Memory consumption monitoring
• Disk Activity - Disk I/O activity indicator
• Network Activity - Network throughput monitoring

Requirements

• macOS 13.0 (Ventura) or later
• Xcode 15.0 or later (for building)
• BlackHole virtual audio driver (recommended)

Installation

Using BlackHole

1. Install BlackHole from existential.audio/blackhole
2. Configure BlackHole as a multi-output device in Audio MIDI Setup
3. Build and run Audio VU Meter
4. The app will automatically detect and select BlackHole

Building from Source

1. Clone the repository
2. Open AudioVUMeter.xcodeproj in Xcode
3. Build and run (⌘R)

git clone <repository-url>
cd AudioVUMeter
open AudioVUMeter.xcodeproj

Usage

Main Window

• Audio Levels: The vertical VU meters show Left (L) and Right (R) channel audio levels
• dB Readings: Numeric display of current audio levels in decibels
• System Meters: Circular gauges showing CPU, RAM, Disk, and Network usage

Controls

• Start/Stop: Toggle audio capture on/off
• Reset: Clear peak hold indicators
• Settings: Access device selection and preferences

Settings

• Input Device: Select audio input source (BlackHole, microphone, etc.)
• Reference Level: Adjust the 0 dB reference point
• Peak Hold Time: Configure how long peak indicators remain visible

Architecture

AudioVUMeter/
├── AudioVUMeterApp.swift    # App entry point
├── ContentView.swift        # Main UI layout
├── VUMeterView.swift        # VU meter components
├── AudioEngine.swift        # Core Audio capture engine
├── SystemMonitor.swift      # System resource monitoring
├── SettingsView.swift       # Settings window
└── Assets.xcassets/         # App icons and colors

Key Components

• AudioEngine: Uses AVAudioEngine to capture audio from the selected input device, calculates RMS levels, and converts to dB
• SystemMonitor: Uses Mach kernel APIs to retrieve CPU, memory, disk, and network statistics
• VUMeterView: SwiftUI views for classic vertical VU meters with segment-based display
• SystemMeterView: Circular gauge components for system metrics

BlackHole Setup Guide

1. Install BlackHole: Download and install from existential.audio

2. Create Multi-Output Device:

   • Open Audio MIDI Setup (Applications → Utilities)
   • Click the + button → Create Multi-Output Device
   • Check both your speakers and BlackHole
   • Set as default output

3. Route Audio:

   • System audio will now go to both speakers and BlackHole
   • Audio VU Meter captures from BlackHole input

API Reference

AudioEngine

// Start/stop audio capture
audioEngine.start()
audioEngine.stop()

// Reset peak indicators
audioEngine.resetPeaks()

// Switch audio device
audioEngine.selectedDeviceID = deviceID
audioEngine.switchDevice()

// Access levels
audioEngine.leftLevel      // 0.0 to 1.0
audioEngine.rightLevel     // 0.0 to 1.0
audioEngine.leftLevelDB    // -60 to 0 dB
audioEngine.rightLevelDB   // -60 to 0 dB

SystemMonitor

// Start/stop monitoring
systemMonitor.startMonitoring()
systemMonitor.stopMonitoring()

// Access metrics (0-100%)
systemMonitor.cpuUsage
systemMonitor.memoryUsage
systemMonitor.diskActivity
systemMonitor.networkActivity

License

MIT License - See LICENSE file for details.

Credits

Inspired by VU-Server by Sasa Karanovic.