include/fft_helpers.h

   1 /*
   2  * fft_helpers.h - some functions around FFT analysis
   3  *
   4  * Copyright (c) 2008 Tobias Doerffel <tobydox/at/users.sourceforge.net>
   5  *
   6  * This file is part of Linux MultiMedia Studio - http://lmms.sourceforge.net
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2 of the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public
  19  * License along with this program (see COPYING); if not, write to the
  20  * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  21  * Boston, MA 02110-1301 USA.
  22  *
  23  */
  24
  25
  26 #ifndef _FFT_HELPERS_H
  27 #define _FFT_HELPERS_H
  28
  29 #include "lmmsconfig.h"
  30 #include "export.h"
  31
  32 #ifdef LMMS_HAVE_FFTW3F
  33
  34 #include <fftw3.h>
  35
  36 const int FFT_BUFFER_SIZE = 2048;
  37
  38 enum WINDOWS
  39 {
  40         KAISER=1,
  41         RECTANGLE,
  42         HANNING,
  43         HAMMING
  44 };
  45
  46 /* returns biggest value from abs_spectrum[spec_size] array
  47  *
  48  *    returns -1 on error
  49  */
  50 float EXPORT maximum( float * _abs_spectrum, unsigned int _spec_size );
  51
  52 /* apply hanning or hamming window to channel
  53  *
  54  *    returns -1 on error
  55  */
  56 int EXPORT hanming( float * _timebuffer, int _length, WINDOWS _type );
  57
  58 /* compute absolute values of complex_buffer, save to absspec_buffer
  59  * take care that - compl_len is not bigger than complex_buffer!
  60  *                - absspec buffer is big enough!
  61  *
  62  *    returns 0 on success, else -1
  63  */
  64 int EXPORT absspec( fftwf_complex * _complex_buffer, float * _absspec_buffer,
  65                                                         int _compl_length );
  66
  67 /* build fewer subbands from many absolute spectrum values
  68  * take care that - compressedbands[] array num_new elements long
  69  *                - num_old > num_new
  70  *
  71  *    returns 0 on success, else -1
  72  */
  73 int EXPORT compressbands( float * _absspec_buffer, float * _compressedband,
  74                         int _num_old, int _num_new, int _bottom, int _top );
  75
  76
  77 int EXPORT calc13octaveband31( float * _absspec_buffer, float * _subbands,
  78                                 int _num_spec, float _max_frequency );
  79
  80 /* compute power of finite time sequence
  81  * take care num_values is length of timesignal[]
  82  *
  83  *    returns power on success, else -1
  84  */
  85 float EXPORT signalpower(float *timesignal, int num_values);
  86
  87 #endif
  88
  89 #endif