Web-Tuner

A Chromium extension that detects the pitch currently playing in your browser and tells you what note it is, along with its tuning.

Features

• Real-time pitch detection from browser audio
• Accurate note identification (e.g., A4, C#5)
• Frequency display in Hz
• Tuning accuracy in cents (±50 cents range)
• Visual graph showing tuning offset:
  • Center line (green) = perfectly in tune (0 cents)
  • Above center (red) = sharp (too high)
  • Below center (blue) = flat (too low)
• In-tune indicator when within ±5 cents

Installation

Load as Unpacked Extension (Developer Mode)

1. Download or clone this repository
2. Open Chrome/Chromium browser
3. Navigate to chrome://extensions/
4. Enable "Developer mode" (toggle in top-right corner)
5. Click "Load unpacked"
6. Select the Web-Tuner directory
7. The extension icon should appear in your browser toolbar

Usage

1. Play audio in any browser tab (YouTube, Spotify, local audio file, etc.)
2. Click the Web Tuner extension icon in the toolbar
3. Click "Start Tuner" button
4. The extension will request permission to capture the tab's audio
5. Once granted, the tuner will display:
   • Current note being played
   • Frequency in Hz
   • Tuning offset in cents
   • Visual graph showing how sharp or flat the note is

Tips

• Make sure audio is actually playing in the tab before starting the tuner
• For best results, use clear, sustained single notes (not chords)
• The tuner works best with frequencies between 80 Hz and 2000 Hz
• If no signal is detected, the display will show "No signal"

Testing with test.html

For testing purposes, open test.html in your browser. This page includes:

• Preset note buttons (A4, C4, E4, G4, C5)
• Custom note selection dropdown
• Detune control to test cents detection (±50 cents)

Simply open the file, play a tone, and activate the tuner extension!

How It Works

The extension uses the Web Audio API to:

1. Capture audio from the current browser tab using chrome.tabCapture
2. Analyze audio using the AnalyserNode with FFT (Fast Fourier Transform)
3. Detect pitch using an autocorrelation algorithm on the time-domain data
4. Calculate note by comparing detected frequency to standard tuning (A4 = 440 Hz)
5. Compute cents deviation from the ideal frequency for that note
6. Display results with visual feedback

What are Cents?

A cent is a logarithmic unit of measure for musical intervals. 100 cents = 1 semitone.

• 0 cents = perfectly in tune
• +50 cents = halfway sharp to the next note
• -50 cents = halfway flat to the previous note
• ±5 cents = generally considered "in tune" for most purposes

Permissions

This extension requires:

• tabCapture - to capture audio from the current browser tab
• activeTab - to access the active tab

Browser Compatibility

• Chrome/Chromium (version 88+)
• Microsoft Edge (Chromium-based)
• Other Chromium-based browsers with Manifest V3 support

License

MIT License - see LICENSE file for details