From c903658f6527ea4b137dafb0697e877e64d636dd Mon Sep 17 00:00:00 2001 From: Robert Date: Thu, 29 Apr 2021 17:14:29 +0200 Subject: [PATCH] added triangle window --- src/FFT.cpp | 40 ++++++++++++++++++++++++++-------------- src/FFT.hpp | 7 ++++--- src/main.cpp | 13 +++++++------ 3 files changed, 37 insertions(+), 23 deletions(-) diff --git a/src/FFT.cpp b/src/FFT.cpp index 021a5a7..76e2557 100644 --- a/src/FFT.cpp +++ b/src/FFT.cpp @@ -12,28 +12,30 @@ using namespace std::complex_literals; typedef std::function 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> radix2dit( const std::vector& list, size_t offset, size_t N, - size_t s, - WindowFunction winFunc) + size_t s) { std::vector> 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> first = radix2dit(list, offset, halfN, s << 1, winFunc); - std::vector> second = radix2dit(list, offset + s, halfN, s << 1, winFunc); + std::vector> first = radix2dit(list, offset, halfN, s << 1); + std::vector> second = radix2dit(list, offset + s, halfN, s << 1); std::complex coeff = -M_PI * 1.0i / (double)halfN; @@ -55,8 +57,7 @@ FFT(const std::vector::const_iterator& begin, const std::vector::const_iterator& end, size_t sampleRate, double minFreq, double maxFreq, - unsigned int zeropadding, - WindowFunctions func, unsigned int width, unsigned int offset) + unsigned int zeropadding) { std::vector signal(begin, end); size_t N = signal.size(); @@ -73,15 +74,10 @@ FFT(const std::vector::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> spectrum = radix2dit(signal, 0, N, 1, f); + std::vector> 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::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)); +} diff --git a/src/FFT.hpp b/src/FFT.hpp index 549d721..f7d8ad3 100644 --- a/src/FFT.hpp +++ b/src/FFT.hpp @@ -5,13 +5,14 @@ enum class WindowFunctions { RECTANGLE, GAUSS, - VON_HANN + VON_HANN, + TRIANGLE }; extern std::vector> FFT(const std::vector::const_iterator& begin, const std::vector::const_iterator& end, size_t sampleRate, double minFreq, double maxFreq, - unsigned int zeropadding, - WindowFunctions func, unsigned int width, unsigned int offset); + unsigned int zeropadding); +extern void SetWindowFunction(WindowFunctions func, unsigned int width); \ No newline at end of file diff --git a/src/main.cpp b/src/main.cpp index 99f4b30..17ddd2a 100644 --- a/src/main.cpp +++ b/src/main.cpp @@ -14,7 +14,8 @@ const std::map 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> spectrum = FFT( audioFile.samples[c-1].cbegin(), audioFile.samples[c-1].cend(), sampleRate, setts.minFreq, setts.maxFreq, - setts.zeropadding, - setts.window, audioFile.samples[c-1].size(), 0 + setts.zeropadding ); 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.window, sampleInterval, 0 + setts.zeropadding ); 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()) ("f,frequency", "Defines the frequency range of the output spectrum (Default: all the frequencies)", cxxopts::value>()) ("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()) - ("w,window", "Specify the window function used (rectangle (default), von-hann, gauss)", cxxopts::value()->default_value("rectangle")) + ("w,window", "Specify the window function used (rectangle (default), von-hann, gauss, triangle)", cxxopts::value()->default_value("rectangle")) ("m,mono", "Analyze only the given channel", cxxopts::value()->default_value("0")) ("files", "Files to fourier transform", cxxopts::value>()) ("h,help", "Print usage")