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/*
Copyright (C) 2008 Paul Davis
Author: Sampo Savolainen
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "fft.h"
#include <stdlib.h>
#include <string.h>
#include <math.h>
FFT::FFT(uint32_t windowSize)
: _windowSize(windowSize),
_dataSize(_windowSize/2),
_iterations(0)
{
_fftInput = (float *) fftwf_malloc(sizeof(float) * _windowSize);
_fftOutput = (float *) fftwf_malloc(sizeof(float) * _windowSize);
_powerAtBin = (float *) malloc(sizeof(float) * _dataSize);
_phaseAtBin = (float *) malloc(sizeof(float) * _dataSize);
_plan = fftwf_plan_r2r_1d(_windowSize, _fftInput, _fftOutput, FFTW_R2HC, FFTW_ESTIMATE);
reset();
}
void
FFT::reset()
{
memset(_powerAtBin, 0, sizeof(float) * _dataSize);
memset(_phaseAtBin, 0, sizeof(float) * _dataSize);
_iterations = 0;
}
void
FFT::analyze(ARDOUR::Sample *input)
{
_iterations++;
memcpy(_fftInput, input, sizeof(float) * _windowSize);
fftwf_execute(_plan);
_powerAtBin[0] += _fftOutput[0] * _fftOutput[0];
_phaseAtBin[0] += 0.0;
float power;
float phase;
#define Re (_fftOutput[i])
#define Im (_fftOutput[_windowSize-i])
for (uint32_t i=1; i < _dataSize - 1; i++) {
power = (Re * Re) + (Im * Im);
phase = atanf(Im / Re);
if (Re < 0.0 && Im > 0.0) {
phase += M_PI;
} else if (Re < 0.0 && Im < 0.0) {
phase -= M_PI;
}
_powerAtBin[i] += power;
_phaseAtBin[i] += phase;
}
#undef Re
#undef Im
}
void
FFT::calculate()
{
if (_iterations > 1) {
for (uint32_t i=0; i < _dataSize - 1; i++) {
_powerAtBin[i] /= (float)_iterations;
_phaseAtBin[i] /= (float)_iterations;
}
_iterations = 1;
}
}
FFT::~FFT()
{
fftwf_destroy_plan(_plan);
free(_powerAtBin);
free(_phaseAtBin);
free(_fftOutput);
free(_fftInput);
}
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