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. Now with physical VU meter hardware support!

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

Physical VU Meter Hardware Support

• 4 Physical Dials - Support for up to 4 physical VU meter dials
• Flexible Channel Mapping - Assign any metric to any dial:
  • Audio Left/Right channels
  • Audio Peak or Mono (L+R)
  • CPU, RAM, Disk, Network usage
• Multiple Serial Protocols:
  • Raw Bytes: [0xAA] [D1] [D2] [D3] [D4] [0x55]
  • Text Commands: CH1:val;CH2:val;CH3:val;CH4:val\n
  • JSON: {"dials":[d1,d2,d3,d4]}
  • VU-Server Compatible: #0:val\n#1:val\n...
• Configurable per dial: Min/max values, inversion, smoothing
• Auto-detection of USB serial devices

Requirements

• macOS 13.0 (Ventura) or later
• Xcode 15.0 or later (for building)
• BlackHole virtual audio driver (recommended)
• USB/Serial VU meter hardware (optional)

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 (Cmd+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
• Hardware Output: Shows status of connected physical VU meters

Controls

• Start/Stop: Toggle audio capture on/off
• Reset: Clear peak hold indicators
• Settings (gear icon): Access device selection and preferences
• Hardware (cable icon): Configure physical VU meter connection

Hardware Setup

1. Connect your USB/Serial VU meter hardware
2. Click the cable icon or go to Settings -> Hardware
3. Select your serial port from the dropdown
4. Choose the appropriate baud rate (default: 115200)
5. Select the communication protocol your hardware uses
6. Assign channels to each dial (Audio L, R, CPU, RAM, etc.)
7. Click "Connect"

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
• Hardware: Serial port, protocol, and dial assignments

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
├── SerialManager.swift      # USB/Serial communication
├── HardwareView.swift       # Hardware configuration UI
├── 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
• SerialManager: Handles USB/Serial communication with physical VU meter hardware
• VUMeterView: SwiftUI views for classic vertical VU meters with segment-based display
• SystemMeterView: Circular gauge components for system metrics

Hardware Protocol Reference

Raw Bytes Protocol

Start: 0xAA
Data:  [Dial1] [Dial2] [Dial3] [Dial4]  (0-255 each)
End:   0x55

Text Command Protocol

CH1:128;CH2:64;CH3:200;CH4:32\n

JSON Protocol

{"dials":[128,64,200,32]}

VU-Server Compatible Protocol

#0:50
#1:75
#2:30
#3:90

Values are percentages (0-100)

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

Compatible Hardware

This app is designed to work with:

• VU Dials by Sasa Karanovic
• Arduino-based VU meters with serial interface
• Any USB/Serial device accepting the supported protocols

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

SerialManager

// Connection
serialManager.connect()
serialManager.disconnect()

// Configuration
serialManager.selectedPortPath = "/dev/cu.usbserial-XXX"
serialManager.baudRate = 115200
serialManager.selectedProtocol = .vuServer

// Dial assignment
serialManager.dialConfigs[0].dialChannel = .audioLeft
serialManager.dialConfigs[1].dialChannel = .audioRight
serialManager.dialConfigs[2].dialChannel = .cpu
serialManager.dialConfigs[3].dialChannel = .ram

License

MIT License - See LICENSE file for details.

Credits

Inspired by VU-Server by Sasa Karanovic.