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85 lines
2.4 KiB
C
85 lines
2.4 KiB
C
/*
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* fft_helpers.h - some functions around FFT analysis
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*
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* Copyright (c) 2008-2012 Tobias Doerffel <tobydox/at/users.sourceforge.net>
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*
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* This file is part of LMMS - http://lmms.io
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (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 GNU
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* 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
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* License along with this program (see COPYING); if not, write to the
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* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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* Boston, MA 02110-1301 USA.
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*
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*/
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#ifndef FFT_HELPERS_H
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#define FFT_HELPERS_H
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#include "export.h"
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#include <fftw3.h>
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const int FFT_BUFFER_SIZE = 2048;
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enum WINDOWS
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{
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KAISER=1,
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RECTANGLE,
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HANNING,
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HAMMING
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};
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/* returns biggest value from abs_spectrum[spec_size] array
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*
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* returns -1 on error
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*/
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float EXPORT maximum( float * _abs_spectrum, unsigned int _spec_size );
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/* apply hanning or hamming window to channel
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*
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* returns -1 on error
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*/
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int EXPORT hanming( float * _timebuffer, int _length, WINDOWS _type );
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/* compute absolute values of complex_buffer, save to absspec_buffer
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* take care that - compl_len is not bigger than complex_buffer!
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* - absspec buffer is big enough!
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*
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* returns 0 on success, else -1
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*/
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int EXPORT absspec( fftwf_complex * _complex_buffer, float * _absspec_buffer,
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int _compl_length );
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/* build fewer subbands from many absolute spectrum values
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* take care that - compressedbands[] array num_new elements long
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* - num_old > num_new
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*
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* returns 0 on success, else -1
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*/
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int EXPORT compressbands( float * _absspec_buffer, float * _compressedband,
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int _num_old, int _num_new, int _bottom, int _top );
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int EXPORT calc13octaveband31( float * _absspec_buffer, float * _subbands,
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int _num_spec, float _max_frequency );
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/* compute power of finite time sequence
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* take care num_values is length of timesignal[]
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*
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* returns power on success, else -1
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*/
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float EXPORT signalpower(float *timesignal, int num_values);
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#endif
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