147 lines
3.2 KiB
C++
147 lines
3.2 KiB
C++
/*
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* Copyright (C) 2008 Sampo Savolainen <v2@iki.fi>
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* Copyright (C) 2019 Robin Gareus <robin@gareus.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "fft.h"
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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using namespace GTKArdour;
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FFT::FFT(uint32_t windowSize)
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: _window_size(windowSize),
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_data_size(_window_size/2),
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_iterations(0),
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_hann_window(0)
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{
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_fftInput = (float *) fftwf_malloc(sizeof(float) * _window_size);
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_fftOutput = (float *) fftwf_malloc(sizeof(float) * _window_size);
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_power_at_bin = (float *) malloc(sizeof(float) * _data_size);
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_phase_at_bin = (float *) malloc(sizeof(float) * _data_size);
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_plan = fftwf_plan_r2r_1d(_window_size, _fftInput, _fftOutput, FFTW_R2HC, FFTW_ESTIMATE);
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reset();
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}
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void
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FFT::reset()
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{
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memset(_power_at_bin, 0, sizeof(float) * _data_size);
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memset(_phase_at_bin, 0, sizeof(float) * _data_size);
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_iterations = 0;
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}
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void
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FFT::analyze(ARDOUR::Sample *input, WindowingType windowing_type)
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{
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_iterations++;
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memcpy(_fftInput, input, sizeof(float) * _window_size);
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if (windowing_type == HANN) {
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float *window = get_hann_window();
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for (uint32_t i = 0; i < _window_size; i++) {
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_fftInput[i] *= window[i];
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}
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}
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fftwf_execute(_plan);
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_power_at_bin[0] += _fftOutput[0] * _fftOutput[0];
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_phase_at_bin[0] += 0.0;
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float power;
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float phase;
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#define Re (_fftOutput[i])
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#define Im (_fftOutput[_window_size-i])
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for (uint32_t i = 1; i < _data_size - 1; ++i) {
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power = (Re * Re) + (Im * Im);
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if (power < 1e-16) {
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phase = 0;
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} else {
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phase = atanf (Im / Re);
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if (Re < 0.0 && Im > 0.0) {
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phase += M_PI;
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} else if (Re < 0.0 && Im < 0.0) {
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phase -= M_PI;
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}
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}
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_power_at_bin[i] += power;
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_phase_at_bin[i] += phase;
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}
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#undef Re
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#undef Im
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}
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void
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FFT::calculate ()
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{
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if (_iterations > 1) {
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for (uint32_t i=0; i < _data_size - 1; i++) {
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_power_at_bin[i] /= (float)_iterations;
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_phase_at_bin[i] /= (float)_iterations;
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}
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_iterations = 1;
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}
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}
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float*
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FFT::get_hann_window ()
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{
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if (_hann_window) {
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return _hann_window;
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}
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_hann_window = (float*) malloc (sizeof (float) * _window_size);
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double sum = 0.0;
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for (uint32_t i = 0; i < _window_size; ++i) {
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_hann_window[i] = 0.81f * (0.5f - (0.5f * (float) cos (2.0f * M_PI * (float)i / (float)(_window_size))));
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sum += _hann_window[i];
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}
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double isum = 1.0 / sum;
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for (uint32_t i = 0; i < _window_size; ++i) {
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_hann_window[i] *= isum;
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}
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return _hann_window;
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}
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FFT::~FFT()
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{
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if (_hann_window) {
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free(_hann_window);
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}
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fftwf_destroy_plan(_plan);
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free(_power_at_bin);
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free(_phase_at_bin);
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fftwf_free(_fftOutput);
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fftwf_free(_fftInput);
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}
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