Tuner Gauge: Chromatic Tuner

An iOS App

Renamed from Free Tuner.

Overview

Tuner Gauge is an iOS chromatic tuner app that provides real-time pitch detection with professional-grade accuracy. Built with SwiftUI and leveraging Apple's Accelerate framework for high-performance audio processing, TunerGauge offers musical enthusiasts a valuable tuning solution with customizable reference standards and easy to understand visualization features.

📱 Screenshots

Device	Screenshot	Description
iPad		Main tuner interface with circular display
iPad		Settings and configuration view
iPhone		Main tuner interface on iPhone
iPhone		A4 frequency picker interface
iPhone		Expanded pitch graph view
iPhone		Decibel meter and signal monitoring

🎵 Core Features

Real-Time Pitch Detection

• Advanced FFT Analysis: Uses Apple's Accelerate framework with 2048-point FFT for precise frequency detection
• Parabolic Interpolation: Improves frequency resolution beyond FFT bin limitations for sub-Hz accuracy
• Noise Threshold Filtering: Intelligent noise gate prevents false detections
• Frequency Range: Supports 69.5 Hz to 4108 Hz - nearly full piano range, help wanted to reach full piano range / higher with accuracy
• Low Latency: Optimized for responsive real-time performance

Visual Tuning Interface

• Circular Tuner Display: Intuitive clock-face gauge design with note markers around the perimeter
• Tuning Needle: Real-time visual indicator showing cents deviation with color coding
• Note Highlighting: Active note prominently displayed with color-coded accuracy
• Octave Support: Full octave range display with clear visual hierarchy

Audio Monitoring

• Decibel Meter: Real-time signal strength monitoring with visual bar meter
• Peak Tracking: Tracks and displays peak levels with decay animation
• Color-Coded Levels:
  • 🟢 Green: Optimal input level (-60 to -40 dB)
  • 🟡 Yellow: Good level (-40 to -20 dB)
  • 🟠 Orange: High level (-20 to -10 dB)
  • 🔴 Red: Clipping risk (-10 to 0 dB)
• Collapsible Interface: Expandable meter with detailed information tooltips

Pitch History & Analysis

• Real-Time Graph: Live frequency tracking over time using SwiftUI Charts
• Configurable History: Adjustable data point limit (25-1000 points)
• Average Frequency: Running average calculation
• Stability Analysis: Automatic pitch stability assessment
• Collapsible Display: Expandable graph interface

Reference Standard Customization

• A4 Frequency Picker: Customizable A4 reference frequency (1-990 Hz)
• Historical Standards: Pre-configured frequencies for different musical periods:
  • Modern Standard (A440)
  • Baroque (A415)
  • Classical (A430)
  • Verdi (A432)
  • Historical (A409)
  • Early Music (A392)
  • Low A4 (A400)
  • High A4 (A480)
• MIDI Reference Note: Configurable MIDI reference note (0-127)
• Common MIDI References: Pre-configured for popular reference notes:
  • A4 (Standard) - MIDI 69
  • C4 (Middle C) - MIDI 60
  • A3 - MIDI 57
  • C5 - MIDI 72
  • G4 - MIDI 67
  • D4 - MIDI 62

Audio Playback for Different Pitches

• Reference Tone Generator: Built-in tone generator for tuning reference
• Multiple Waveforms: Sine, Square, Triangle, and Sawtooth waveforms
• Real-Time Frequency Control: Adjustable frequency with live playback
• Continuous Playback: Sustained tone generation for extended tuning sessions

User Interface Features

• iPad Optimization: Enhanced font sizes and layout for iPad users
• Dark Mode Support: Full dark mode compatibility
• Responsive Design: Adaptive layouts for different screen sizes
• Comprehensive Accessibility: Full VoiceOver support with dynamic content handling
• Gesture Controls: Tap to start/stop listening
• Collapsible Sections: Expandable interface elements for cleaner layout

Settings & Customization

• Display Options: Toggle visibility of pitch graph, signal strength, and reference labels
• Pitch History Configuration: Adjustable maximum history size
• Persistent Settings: All preferences saved using @AppStorage
• Collapsible Sections: Organized settings with expandable categories

🛠 Technical Architecture

Audio Processing Pipeline

1. Audio Input: AVAudioEngine with microphone input
2. FFT Analysis: 2048-point FFT using Accelerate framework
3. Frequency Detection: Peak detection with parabolic interpolation
4. Note Conversion: Equal temperament calculation with cents deviation
5. Real-Time Updates: Async stream processing for responsive UI

Key Components

• AudioInputManager: Handles audio session and real-time processing
• PitchAnalyzer: FFT-based frequency analysis with interpolation
• NoteConverter: Frequency-to-note conversion with customizable references
• PitchPlayer: Reference tone generator with multiple waveforms
• TunerView: Main interface with circular tuner display
• SettingsView: Comprehensive settings and reference configuration

Performance Optimizations

• Accelerate Framework: Hardware-accelerated FFT processing
• Async Streams: Non-blocking audio processing
• Memory Management: Efficient buffer handling and cleanup
• UI Updates: MainActor coordination for smooth interface updates

📱 Platform Support

iOS Requirements

• Minimum iOS Version: iOS 17.0+
• Device Support: iPhone and iPad
• Permissions: Microphone access required
• Hardware: Optimized for devices with A-series chips

iPad Enhancements

• Larger Fonts: Enhanced typography for better readability
• Adaptive Layouts: Optimized spacing and sizing
• Touch Interface: Improved touch targets and gestures

🎨 Design Philosophy

User Experience

• Intuitive Interface: Clock-face like gauge tuner design familiar to many people
• Visual Feedback: Color-coded accuracy indicators
• Responsive Design: Real-time updates on all displays

Professional Standards

• Musical Accuracy: Equal temperament with precise cents calculation
• Historical Support: Multiple tuning standards for period performance
• Professional Tools: Reference tone generator and signal monitoring
• Data Visualization: Comprehensive pitch analysis and history