diff options
| -rw-r--r-- | Userland/Applications/SoundPlayer/BarsVisualizationWidget.cpp | 2 | ||||
| -rw-r--r-- | Userland/Libraries/LibDSP/CMakeLists.txt | 1 | ||||
| -rw-r--r-- | Userland/Libraries/LibDSP/FFT.cpp | 62 | ||||
| -rw-r--r-- | Userland/Libraries/LibDSP/FFT.h | 37 |
4 files changed, 36 insertions, 66 deletions
diff --git a/Userland/Applications/SoundPlayer/BarsVisualizationWidget.cpp b/Userland/Applications/SoundPlayer/BarsVisualizationWidget.cpp index 0c87ced853..3e6ca3d75b 100644 --- a/Userland/Applications/SoundPlayer/BarsVisualizationWidget.cpp +++ b/Userland/Applications/SoundPlayer/BarsVisualizationWidget.cpp @@ -26,7 +26,7 @@ void BarsVisualizationWidget::paint_event(GUI::PaintEvent& event) if (m_sample_buffer.is_empty()) return; - LibDSP::fft(m_sample_buffer, false); + LibDSP::fft(m_sample_buffer.span(), false); double max = AK::sqrt(m_sample_count * 2.); double freq_bin = m_samplerate / (double)m_sample_count; diff --git a/Userland/Libraries/LibDSP/CMakeLists.txt b/Userland/Libraries/LibDSP/CMakeLists.txt index f7dc72fcd1..a5de6f120e 100644 --- a/Userland/Libraries/LibDSP/CMakeLists.txt +++ b/Userland/Libraries/LibDSP/CMakeLists.txt @@ -3,7 +3,6 @@ set(SOURCES Track.cpp Effects.cpp Synthesizers.cpp - FFT.cpp ) serenity_lib(LibDSP dsp) diff --git a/Userland/Libraries/LibDSP/FFT.cpp b/Userland/Libraries/LibDSP/FFT.cpp deleted file mode 100644 index 8083333f96..0000000000 --- a/Userland/Libraries/LibDSP/FFT.cpp +++ /dev/null @@ -1,62 +0,0 @@ -/* - * Copyright (c) 2021, Cesar Torres <shortanemoia@protonmail.com> - * - * SPDX-License-Identifier: BSD-2-Clause - */ - -#include "FFT.h" -#include <AK/Complex.h> -#include <AK/Math.h> - -namespace LibDSP { - -// This function uses the input vector as output too. therefore, if you wish to -// leave it intact, pass a copy to this function -// -// The sampling frequency must be more than twice the frequency to resolve. -// The sample window must be at least large enough to reflect the periodicity -// of the smallest frequency to be resolved. -// -// For example, to resolve a 10 KHz and a 2 Hz sine waves we need at least -// a samplerate of 20 KHz and a window of 0.5 seconds -// -// If invert is true, this function computes the inverse discrete fourier transform. -// -// The data vector must be a power of 2 -// Adapted from https://cp-algorithms.com/algebra/fft.html -void fft(Vector<Complex<double>>& sample_data, bool invert) -{ - int n = sample_data.size(); - auto data = sample_data.data(); - - for (int i = 1, j = 0; i < n; i++) { - int bit = n >> 1; - for (; j & bit; bit >>= 1) - j ^= bit; - j ^= bit; - - if (i < j) - swap(data[i], data[j]); - } - - for (int len = 2; len <= n; len <<= 1) { - double ang = 2 * AK::Pi<double> / len * (invert ? -1 : 1); - Complex<double> wlen(AK::cos(ang), AK::sin(ang)); - for (int i = 0; i < n; i += len) { - Complex<double> w = { 1., 0. }; - for (int j = 0; j < len / 2; j++) { - Complex<double> u = data[i + j], v = data[i + j + len / 2] * w; - data[i + j] = u + v; - data[i + j + len / 2] = u - v; - w *= wlen; - } - } - } - - if (invert) { - for (int i = 0; i < n; i++) - data[i] /= n; - } -} - -} diff --git a/Userland/Libraries/LibDSP/FFT.h b/Userland/Libraries/LibDSP/FFT.h index d13d358af2..c9db991b1d 100644 --- a/Userland/Libraries/LibDSP/FFT.h +++ b/Userland/Libraries/LibDSP/FFT.h @@ -7,10 +7,43 @@ #pragma once #include <AK/Complex.h> -#include <AK/Vector.h> +#include <AK/Math.h> +#include <AK/Span.h> namespace LibDSP { -void fft(Vector<Complex<double>>& sample_data, bool invert = false); +constexpr void fft(Span<Complex<double>> sample_data, bool invert = false) +{ + int n = sample_data.size(); + + for (int i = 1, j = 0; i < n; i++) { + int bit = n >> 1; + for (; j & bit; bit >>= 1) + j ^= bit; + j ^= bit; + + if (i < j) + swap(sample_data[i], sample_data[j]); + } + + for (int len = 2; len <= n; len <<= 1) { + double ang = 2 * AK::Pi<double> / len * (invert ? -1 : 1); + Complex<double> wlen(AK::cos(ang), AK::sin(ang)); + for (int i = 0; i < n; i += len) { + Complex<double> w = { 1., 0. }; + for (int j = 0; j < len / 2; j++) { + Complex<double> u = sample_data[i + j], v = sample_data[i + j + len / 2] * w; + sample_data[i + j] = u + v; + sample_data[i + j + len / 2] = u - v; + w *= wlen; + } + } + } + + if (invert) { + for (int i = 0; i < n; i++) + sample_data[i] /= n; + } +} } |