added triangle window

src/FFT.cpp

@@ -12,28 +12,30 @@ using namespace std::complex_literals;
 
 typedef std::function<double(unsigned int)> WindowFunction;
 
+static WindowFunction window;
+
 inline double WindowRectangle(unsigned int k, unsigned int offset, unsigned int width);
 inline double WindowVonHann(unsigned int k, unsigned int offset, unsigned int width);
 inline double WindowGauss(unsigned int k, unsigned int offset, unsigned int width);
+inline double WindowTriangle(unsigned int k, unsigned int offset, unsigned int width);
 
 std::vector<std::complex<double>> 
 radix2dit(
 	const std::vector<double>& list,
 	size_t offset,
 	size_t N, 
-	size_t s,
+	size_t s)
-	WindowFunction winFunc)
 {
 	std::vector<std::complex<double>> output(N);
 	if (N == 1)
 	{
-		output[0] = winFunc(offset) * (list[offset]);
+		output[0] = window(offset) * (list[offset]);
 	}
 	else
 	{
 		size_t halfN = N >> 1;
-		std::vector<std::complex<double>> first = radix2dit(list, offset, halfN, s << 1, winFunc);
+		std::vector<std::complex<double>> first = radix2dit(list, offset, halfN, s << 1);
-		std::vector<std::complex<double>> second = radix2dit(list, offset + s, halfN, s << 1, winFunc);
+		std::vector<std::complex<double>> second = radix2dit(list, offset + s, halfN, s << 1);
 
 		std::complex<double> coeff = -M_PI * 1.0i / (double)halfN;
 
@@ -55,8 +57,7 @@ FFT(const std::vector<double>::const_iterator& begin,
 	const std::vector<double>::const_iterator& end,
 	size_t sampleRate,
 	double minFreq, double maxFreq,
-	unsigned int zeropadding,
+	unsigned int zeropadding)
-	WindowFunctions func, unsigned int width, unsigned int offset)
 {
 	std::vector<double> signal(begin, end);
 	size_t N = signal.size();
@@ -73,15 +74,10 @@ FFT(const std::vector<double>::const_iterator& begin,
 	}
 
 	WindowFunction f;
-	switch (func)
+	
-	{
-	case WindowFunctions::RECTANGLE:	f = std::bind(WindowRectangle, std::placeholders::_1, offset, width); break;
-	case WindowFunctions::VON_HANN:		f = std::bind(WindowVonHann, std::placeholders::_1, offset, width); break;
-	case WindowFunctions::GAUSS:		f = std::bind(WindowGauss, std::placeholders::_1, offset, width); break;
-	} 
 
 
-	std::vector<std::complex<double>> spectrum = radix2dit(signal, 0, N, 1, f);
+	std::vector<std::complex<double>> spectrum = radix2dit(signal, 0, N, 1);
 	double freqRes = (double)sampleRate / (double)N;
 	double nyquistLimit = (double)sampleRate / 2.0f;
 
@@ -99,6 +95,17 @@ FFT(const std::vector<double>::const_iterator& begin,
 	return output;
 }
 
+void SetWindowFunction(WindowFunctions func, unsigned int width)
+{
+	switch (func)
+	{
+	case WindowFunctions::RECTANGLE:	window = std::bind(WindowRectangle, std::placeholders::_1, 0, width); break;
+	case WindowFunctions::VON_HANN:		window = std::bind(WindowVonHann, std::placeholders::_1, 0, width); break;
+	case WindowFunctions::GAUSS:		window = std::bind(WindowGauss, std::placeholders::_1, 0, width); break;
+	case WindowFunctions::TRIANGLE:		window = std::bind(WindowTriangle, std::placeholders::_1, 0, width); break;
+	}
+}
+
 inline double WindowRectangle(unsigned int k, unsigned int offset, unsigned int width)
 {
 	return ((offset < k) && (k < width));
@@ -114,3 +121,8 @@ inline double WindowGauss(unsigned int k, unsigned int offset, unsigned int widt
 	double coeff = (k - (width - 1) * 0.5f) / (0.4f * (width - 1) * 0.5f);
 	return ((offset < k) && (k < width)) ? (std::exp(-0.5f * coeff * coeff)) : 0;
 }
+
+inline double WindowTriangle(unsigned int k, unsigned int offset, unsigned int width)
+{
+	return 1.0f - std::abs(((double)k - ((double)width / 2.0f)) / ((double)width / 2.0f));
+}

src/FFT.hpp

@@ -5,13 +5,14 @@
 enum class WindowFunctions {
 	RECTANGLE,
 	GAUSS,
-	VON_HANN
+	VON_HANN,
+	TRIANGLE
 };
 
 extern std::vector<std::pair<double, double>> FFT(const std::vector<double>::const_iterator& begin,
 	const std::vector<double>::const_iterator& end,
 	size_t sampleRate,
 	double minFreq, double maxFreq,
-	unsigned int zeropadding,
+	unsigned int zeropadding);
-	WindowFunctions func, unsigned int width, unsigned int offset);
 
+extern void SetWindowFunction(WindowFunctions func, unsigned int width);

src/main.cpp

@@ -14,7 +14,8 @@
 const std::map<std::string, WindowFunctions> FUNCTIONS {
 	{"rectangle", WindowFunctions::RECTANGLE},
 	{"von-hann", WindowFunctions::VON_HANN},
-	{"gauss", WindowFunctions::GAUSS}
+	{"gauss", WindowFunctions::GAUSS},
+	{"triangle", WindowFunctions::TRIANGLE}
 };
 
 struct Settings {
@@ -63,14 +64,14 @@ int main(int argc, char** argv)
 
 			if (setts.splitInterval == 0.0f)
 			{
+				SetWindowFunction(setts.window, audioFile.samples[c-1].size());
 				std::vector<std::pair<double, double>> spectrum = 
 					FFT(
 						audioFile.samples[c-1].cbegin(), 
 						audioFile.samples[c-1].cend(), 
 						sampleRate,
 						setts.minFreq, setts.maxFreq,
-						setts.zeropadding,
+						setts.zeropadding
-						setts.window, audioFile.samples[c-1].size(), 0
 					);
 
 				output[chName] = nlohmann::json::array();
@@ -81,6 +82,7 @@ int main(int argc, char** argv)
 			else
 			{
 				int sampleInterval = sampleRate * setts.splitInterval / 1000;
+				SetWindowFunction(setts.window, sampleInterval);
 				int currentSample;
 				for (currentSample = 0; currentSample < audioFile.samples[c - 1].size(); currentSample += sampleInterval)
 				{
@@ -93,8 +95,7 @@ int main(int argc, char** argv)
 							),
 							sampleRate,
 							setts.minFreq, setts.maxFreq,
-							setts.zeropadding,
+							setts.zeropadding
-							setts.window, sampleInterval, 0
 						);
 
 					output[chName].push_back({
@@ -137,7 +138,7 @@ Settings Parse(int argc, char** argv)
 			("i,interval", "Splits audio file into intervals of length i milliseconds and transforms them individually (0 to not split file)", cxxopts::value<float>())
 			("f,frequency", "Defines the frequency range of the output spectrum (Default: all the frequencies)", cxxopts::value<std::vector<double>>())
 			("p,pad", "Add extra zero-padding. By default, the program will pad the signals with 0s until the number of samples is a power of 2 (this would be equivalent to -p 1). With this option you can tell the program to instead pad until the power of 2 after the next one (-p 2) etc. This increases frequency resolution", cxxopts::value<unsigned int>())
-			("w,window", "Specify the window function used (rectangle (default), von-hann, gauss)", cxxopts::value<std::string>()->default_value("rectangle"))
+			("w,window", "Specify the window function used (rectangle (default), von-hann, gauss, triangle)", cxxopts::value<std::string>()->default_value("rectangle"))
 			("m,mono", "Analyze only the given channel", cxxopts::value<unsigned int>()->default_value("0"))
 			("files", "Files to fourier transform", cxxopts::value<std::vector<std::filesystem::path>>())
 			("h,help", "Print usage")