lauchmelder/spectralyze
1
0
Fork 0
Code Issues Pull requests Actions Packages Projects Releases Wiki Activity

added triangle window

Browse source
This commit is contained in:
Robert 2021-04-29 17:14:29 +02:00
parent fbc2851533
commit c903658f65
3 changed files with 37 additions and 23 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

40
src/FFT.cpp
View file

@ -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,
WindowFunction winFunc)
size_t s)
{
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>> second = radix2dit(list, offset + s, 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);
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,
WindowFunctions func, unsigned int width, unsigned int offset)
unsigned int zeropadding)
{
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));
}

7
src/FFT.hpp
View file

@ -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,
WindowFunctions func, unsigned int width, unsigned int offset);
unsigned int zeropadding);
extern void SetWindowFunction(WindowFunctions func, unsigned int width);

13
src/main.cpp
View file

@ -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.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<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")