54 lines
2.5 KiB
C
54 lines
2.5 KiB
C
/***************************************************************************
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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 *
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* along with this program; if not, write to the *
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* Free Software Foundation, Inc., *
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* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
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***************************************************************************/
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// Very fast DCT (discrete cosine transform) implementation based on IEEE signal proc, 1992 #8 .
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#include <stdio.h>
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#include <math.h>
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#include <stdlib.h>
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#define FDCT_TOTSIZE 16384 /* !!! QUESTA È LA GRANDEZZA DEL BUFFER --DEVE-- ESSERE UNA POTENZA DI 2 !!! */
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#define FDCT_POW 14 /* ln( FDCT_TOTSIZE ) */
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#define FDCT_TSO2 8192 /* FDCT_TOTSIZE / 2 */
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#define FDCT_TSO4 4096 /* FDCT_TOTSIZE / 4 */
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#define FDCT_2OTS 0.00012207 /* 2 / FDCT_TOTSIZE */
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#define FDCT_2OTS_SQ 0.011048543 /* sqrt( 2 / FDCT_TOTSIZE ) */
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#define FDCT_FACTOR 0.7071067814
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// fast DCT main structure
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typedef struct {
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double * transform;
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double * ctable;
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}
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fdct_t;
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// initialize the structure with data
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void fdct_init( fdct_t *dct, unsigned char *data );
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// reverse data 'til size-th byte
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inline void fdct_bitrev( double *data, unsigned int size );
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// complete data reversing
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inline void fdct_scramble( double *data );
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// compute cosine coefficents
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inline void fdct_butterflies( fdct_t *dct );
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// compute FDCT sums on data
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inline void fdct_sums(double *data);
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// compute FDCT
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inline void fdct_compute( fdct_t *dct );
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// compute FDCT vector sum, where k is the normalizing factor and neutral an optional mask to subtract
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inline double fdct_sum( fdct_t *dct, double div, unsigned char *neutral, unsigned int neutral_size );
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// release FDCT structure
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void fdct_release( fdct_t *dct );
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