From 308a53c389cdc2631860f434989cd57efbf91145 Mon Sep 17 00:00:00 2001
From: Roland Stigge <stigge@antcom.de>
Date: Sun, 17 Feb 2019 14:53:33 +0100
Subject: Implemented Tuner

---
 tuner.cpp | 40 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 37 insertions(+), 3 deletions(-)

(limited to 'tuner.cpp')

diff --git a/tuner.cpp b/tuner.cpp
index d1833a3..3013390 100644
--- a/tuner.cpp
+++ b/tuner.cpp
@@ -2,12 +2,19 @@
 
 #include "autocorrelation.h"
 #include "fft.h"
+#include "util.h"
+
+#include <algorithm>
+#include <cmath>
+
+using namespace RIT;
 
 struct RIT::Tuner::Impl {
 public:
-	Impl(int size, int f_sample): mAC(size), m_f_sample(f_sample) {}
+	Impl(int size, int f_sample): mAC(size), m_f_sample(f_sample), mSize(size) {}
 	RIT::AutoCorrelation mAC;
 	int m_f_sample;
+	int mSize;
 };
 
 RIT::Tuner::Tuner(int size, int f_sample): mImpl(std::make_unique<RIT::Tuner::Impl>(size, f_sample))
@@ -16,9 +23,36 @@ RIT::Tuner::Tuner(int size, int f_sample): mImpl(std::make_unique<RIT::Tuner::Im
 
 RIT::Tuner::~Tuner(){}
 
+namespace {
+	const std::vector<std::string> noteNames{ "A", "A#", "B", "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#" };
+	const double base = std::pow(2.0, 1./12);
+
+	RIT::Pitch getPitch(double f)
+	{
+		double noteIndexD = std::log(f / 110.0) / std::log(base) + 0.5;
+
+		double noteIndexI{};
+		double deviation = std::modf(noteIndexD, &noteIndexI) - 0.5;
+		int noteIndex = int(noteIndexI);
+
+		noteIndex %= 12;
+		
+		return RIT::Pitch {f, deviation, noteNames[noteIndex]};
+	}
+}
+
 RIT::Pitch RIT::Tuner::operator() (const std::vector<std::complex<double>> &v)
 {
-	std::vector<std::complex<double>> autoCorrelation = mImpl->mAC(v);
+	std::vector<double> autoCorrelation = magnitudes(mImpl->mAC(v));
+
+	auto maxElement = std::max_element(std::begin(autoCorrelation) + 1, std::begin(autoCorrelation) + mImpl->mSize / 2);
+
+	int index = maxElement - std::begin(autoCorrelation);
+
+	if (autoCorrelation[index] > autoCorrelation[index - 1] && autoCorrelation[index] > autoCorrelation[index + 1]) {
+		double f = double(mImpl->m_f_sample) / index;
+		return getPitch(f);
+	}
 
-	return Pitch();
+	return Pitch{};
 }
-- 
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