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added mertz method

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This commit is contained in:
Robert 2021-04-29 23:21:52 +02:00
parent 291b985bc3
commit f2ad3bd04a
3 changed files with 16 additions and 5 deletions
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9
src/FFT.cpp
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@ -58,7 +58,8 @@ 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,
bool mertz)
{
std::vector<double> signal(begin, end);
size_t N = signal.size();
@ -89,7 +90,11 @@ FFT(const std::vector<double>::const_iterator& begin,
for (int k = freq / freqRes; freq < nyquistLimit && freq < maxFreq; k++)
{
output.push_back(std::make_pair(freq, 2.0f * std::abs(spectrum[k]) / (double)N));
if(!mertz)
output.push_back(std::make_pair(freq, 2.0f * std::abs(spectrum[k]) / (double)N));
else
output.push_back(std::make_pair(freq, 2.0f * (spectrum[k] * std::exp(-1i * std::arg(spectrum[k]))).real() / (double)N));
freq += freqRes;
}

3
src/FFT.hpp
View file

@ -14,6 +14,7 @@ extern std::vector<std::pair<double, double>> FFT(const std::vector<double>::con
const std::vector<double>::const_iterator& end,
size_t sampleRate,
double minFreq, double maxFreq,
unsigned int zeropadding);
unsigned int zeropadding,
bool mertz);
extern void SetWindowFunction(WindowFunctions func, unsigned int width);

9
src/main.cpp
View file

@ -26,6 +26,7 @@ struct Settings {
double minFreq, maxFreq;
unsigned int analyzeChannel;
unsigned int zeropadding;
bool mertz;
WindowFunctions window;
};
@ -72,7 +73,8 @@ int main(int argc, char** argv)
audioFile.samples[c-1].cend(),
sampleRate,
setts.minFreq, setts.maxFreq,
setts.zeropadding
setts.zeropadding,
setts.mertz
);
output[chName] = nlohmann::json::array();
@ -96,7 +98,8 @@ int main(int argc, char** argv)
),
sampleRate,
setts.minFreq, setts.maxFreq,
setts.zeropadding
setts.zeropadding,
setts.mertz
);
output[chName].push_back({
@ -140,6 +143,7 @@ Settings Parse(int argc, char** argv)
("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, triangle, blackman (3-term))", cxxopts::value<std::string>()->default_value("rectangle"))
("mertz", "Use the Mertz method to phase-correct the complex Fourier spectrum")
("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")
@ -176,6 +180,7 @@ Settings Parse(int argc, char** argv)
setts.splitInterval = (result.count("interval") ? result["interval"].as<float>() : 0.0f);
setts.analyzeChannel = (result.count("mono") ? result["mono"].as<unsigned int>() : 0);
setts.zeropadding = (result.count("pad") ? result["pad"].as<unsigned int>() : 1);
setts.mertz = (result.count("mertz") ? true : false);
if (!result.count("window"))
{