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77 lines
2.8 KiB
C
77 lines
2.8 KiB
C
/*
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* Header file for hardcoded mpegaudiodec tables
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*
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* Copyright (c) 2009 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg 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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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVCODEC_MPEGAUDIO_TABLEGEN_H
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#define AVCODEC_MPEGAUDIO_TABLEGEN_H
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#include <stdint.h>
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#include <math.h>
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#include "libavutil/attributes.h"
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#define TABLE_4_3_SIZE (8191 + 16)*4
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#if CONFIG_HARDCODED_TABLES
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#define mpegaudio_tableinit()
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#include "libavcodec/mpegaudio_tables.h"
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#else
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static int8_t table_4_3_exp[TABLE_4_3_SIZE];
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static uint32_t table_4_3_value[TABLE_4_3_SIZE];
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static uint32_t exp_table_fixed[512];
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static uint32_t expval_table_fixed[512][16];
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static float exp_table_float[512];
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static float expval_table_float[512][16];
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#define FRAC_BITS 23
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#define IMDCT_SCALAR 1.759
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static av_cold void mpegaudio_tableinit(void)
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{
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int i, value, exponent;
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for (i = 1; i < TABLE_4_3_SIZE; i++) {
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double value = i / 4;
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double f, fm;
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int e, m;
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/* cbrtf() isn't available on all systems, so we use powf(). */
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f = value / IMDCT_SCALAR * pow(value, 1.0 / 3.0) * pow(2, (i & 3) * 0.25);
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fm = frexp(f, &e);
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m = (uint32_t)(fm * (1LL << 31) + 0.5);
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e += FRAC_BITS - 31 + 5 - 100;
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/* normalized to FRAC_BITS */
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table_4_3_value[i] = m;
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table_4_3_exp[i] = -e;
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}
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for (exponent = 0; exponent < 512; exponent++) {
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for (value = 0; value < 16; value++) {
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/* cbrtf() isn't available on all systems, so we use powf(). */
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double f = (double)value * pow(value, 1.0 / 3.0) * pow(2, (exponent - 400) * 0.25 + FRAC_BITS + 5) / IMDCT_SCALAR;
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/* llrint() isn't always available, so round and cast manually. */
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expval_table_fixed[exponent][value] = (long long int) (f < 0xFFFFFFFF ? floor(f + 0.5) : 0xFFFFFFFF);
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expval_table_float[exponent][value] = f;
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}
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exp_table_fixed[exponent] = expval_table_fixed[exponent][1];
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exp_table_float[exponent] = expval_table_float[exponent][1];
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}
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}
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#endif /* CONFIG_HARDCODED_TABLES */
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#endif /* AVCODEC_MPEGAUDIO_TABLEGEN_H */
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