diff options
Diffstat (limited to 'gtk2_ardour/fft.cc')
-rw-r--r-- | gtk2_ardour/fft.cc | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/gtk2_ardour/fft.cc b/gtk2_ardour/fft.cc new file mode 100644 index 0000000000..92f52bb64e --- /dev/null +++ b/gtk2_ardour/fft.cc @@ -0,0 +1,107 @@ +/* + 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); +} |