lauchmelder/spectralyze
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added zero padding

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Robert 2021-04-28 23:11:16 +02:00
parent ea91cfb368
commit b7e7790d86
2 changed files with 15 additions and 3 deletions
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8
src/FFT.hpp
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@ -53,7 +53,8 @@ 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)
double minFreq, double maxFreq,
unsigned int zeropadding)
{
std::vector<double> signal(begin, end);
size_t N = signal.size();
@ -64,6 +65,11 @@ FFT(const std::vector<double>::const_iterator& begin,
N++;
}
if (zeropadding > 1) {
N = (signal.size() << (zeropadding - 1));
signal.insert(signal.end(), N - signal.size(), 0);
}
std::vector<std::complex<double>> spectrum = radix2dit(signal.cbegin(), N, 1);
double freqRes = (double)sampleRate / (double)N;
double nyquistLimit = (double)sampleRate / 2.0f;

10
src/main.cpp
View file

@ -16,6 +16,7 @@ struct Settings {
float splitInterval;
double minFreq, maxFreq;
unsigned int analyzeChannel;
unsigned int zeropadding;
};
Settings Parse(int argc, char** argv);
@ -59,7 +60,9 @@ int main(int argc, char** argv)
audioFile.samples[c-1].cbegin(),
audioFile.samples[c-1].cend(),
sampleRate,
setts.minFreq, setts.maxFreq);
setts.minFreq, setts.maxFreq,
setts.zeropadding
);
output[chName] = nlohmann::json::array();
for (const std::pair<double, double>& pair : spectrum) {
@ -80,7 +83,8 @@ int main(int argc, char** argv)
audioFile.samples[c-1].cend()
),
sampleRate,
setts.minFreq, setts.maxFreq
setts.minFreq, setts.maxFreq,
setts.zeropadding
);
output[chName].push_back({
@ -122,6 +126,7 @@ Settings Parse(int argc, char** argv)
("q,quiet", "Suppress text output", cxxopts::value<bool>()->default_value("false"))
("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>())
("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")
@ -157,6 +162,7 @@ Settings Parse(int argc, char** argv)
setts.quiet = (result.count("quiet") ? result["quiet"].as<bool>() : false);
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);
if (setts.maxFreq <= setts.minFreq && (setts.maxFreq != 0))