StringPitcher

Ultra low-latency pitch detection library for guitar and bass instruments. Works in browsers and Node.js via WebAssembly.

Features

• Real-time pitch detection using McLeod Pitch Method (MPM)
• Support for 6-string guitar, 4-string bass, and 5-string bass
• 12 built-in tuning presets (Standard, Drop D, Open G, etc.)
• Chromatic mode for detecting any note
• Configurable A4 reference pitch (432-448 Hz)
• < 20ms latency

Installation

npm install stringpitcher-wasm
# or
pnpm add stringpitcher-wasm
# or
yarn add stringpitcher-wasm

Quick Start

import { StringPitcher, Instrument, TuningPreset } from 'stringpitcher-wasm';

// Create tuner with your audio sample rate
const tuner = new StringPitcher(48000);

// Configure instrument and tuning
tuner.setInstrument(Instrument.Guitar6String);
tuner.setTuningPreset(TuningPreset.Standard);

// Process audio samples (from Web Audio API, etc.)
function processAudio(audioBuffer) {
  const samples = audioBuffer.getChannelData(0); // Float32Array
  const result = tuner.processAudio(samples);

  if (result) {
    console.log(`Note: ${result.noteName}${result.octave}`);
    console.log(`Frequency: ${result.frequency.toFixed(1)} Hz`);
    console.log(`Cents off: ${result.centDeviation.toFixed(1)}`);
    console.log(`In tune: ${result.isInTune}`);
    console.log(`Direction: ${result.tuningDirection}`); // -1: flat, 0: in tune, 1: sharp
  }
}

Web Audio API Example

import { StringPitcher } from 'stringpitcher-wasm';

async function startTuner() {
  const audioContext = new AudioContext();
  const tuner = new StringPitcher(audioContext.sampleRate);

  // Get microphone access
  const stream = await navigator.mediaDevices.getUserMedia({ audio: true });
  const source = audioContext.createMediaStreamSource(stream);

  // Create analyzer for getting audio data
  const analyzer = audioContext.createAnalyser();
  analyzer.fftSize = 4096;
  source.connect(analyzer);

  const buffer = new Float32Array(analyzer.fftSize);

  function detect() {
    analyzer.getFloatTimeDomainData(buffer);
    const result = tuner.processAudio(buffer);

    if (result && result.confidence > 0.5) {
      updateUI(result);
    }

    requestAnimationFrame(detect);
  }

  detect();
}

API Reference

StringPitcher

Constructor

new StringPitcher(sampleRate: number)

Methods

| Method | Description | |--------|-------------| | processAudio(samples: Float32Array) | Process audio samples, returns PitchResult or null | | reset() | Reset tuner state (call after audio interruption) | | setInstrument(instrument: number) | Set instrument type | | setTuningPreset(preset: number) | Set tuning preset | | setReferencePitch(pitch: number) | Set A4 reference (432-448 Hz) | | setChromaticMode(enabled: boolean) | Enable/disable chromatic mode | | setNoiseGate(thresholdDb: number) | Set noise gate (-60 to 0 dB) |

PitchResult

| Property | Type | Description | |----------|------|-------------| | frequency | number | Detected frequency in Hz | | confidence | number | Detection confidence (0-1) | | noteName | string | Note name (e.g., "E", "A#") | | octave | number | Octave number | | centDeviation | number | Cents off from target (-50 to +50) | | isInTune | boolean | Whether note is in tune (within threshold) | | tuningDirection | number | -1: flat, 0: in tune, 1: sharp | | matchedString | number | Matched string index (0-5) or -1 | | signalLevel | number | Input signal level (0-1) |

Instrument

| Constant | Value | Description | |----------|-------|-------------| | Guitar6String | 0 | 6-string guitar | | Bass4String | 1 | 4-string bass | | Bass5String | 2 | 5-string bass |

TuningPreset

| Constant | Value | Description | |----------|-------|-------------| | Standard | 0 | Standard tuning | | HalfStepDown | 1 | Half step down | | WholeStepDown | 2 | Whole step down | | DropD | 5 | Drop D | | DropC | 6 | Drop C | | OpenG | 9 | Open G | | OpenD | 10 | Open D | | DADGAD | 11 | DADGAD |

License

MIT