mirror of
https://github.com/ossrs/srs.git
synced 2025-03-09 15:49:59 +00:00
91 lines
3.1 KiB
C
91 lines
3.1 KiB
C
/*
|
|
* Header file for hardcoded mpegaudiodec tables
|
|
*
|
|
* Copyright (c) 2009 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
|
|
*
|
|
* This file is part of FFmpeg.
|
|
*
|
|
* FFmpeg is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2.1 of the License, or (at your option) any later version.
|
|
*
|
|
* FFmpeg 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
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with FFmpeg; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
#ifndef AVCODEC_MPEGAUDIO_TABLEGEN_H
|
|
#define AVCODEC_MPEGAUDIO_TABLEGEN_H
|
|
|
|
#include <stdint.h>
|
|
#include <math.h>
|
|
#include "libavutil/attributes.h"
|
|
|
|
#define TABLE_4_3_SIZE (8191 + 16)*4
|
|
#if CONFIG_HARDCODED_TABLES
|
|
#define mpegaudio_tableinit()
|
|
#include "libavcodec/mpegaudio_tables.h"
|
|
#else
|
|
static int8_t table_4_3_exp[TABLE_4_3_SIZE];
|
|
static uint32_t table_4_3_value[TABLE_4_3_SIZE];
|
|
static uint32_t exp_table_fixed[512];
|
|
static uint32_t expval_table_fixed[512][16];
|
|
static float exp_table_float[512];
|
|
static float expval_table_float[512][16];
|
|
|
|
#define FRAC_BITS 23
|
|
#define IMDCT_SCALAR 1.759
|
|
|
|
static av_cold void mpegaudio_tableinit(void)
|
|
{
|
|
int i, value, exponent;
|
|
static const double exp2_lut[4] = {
|
|
1.00000000000000000000, /* 2 ^ (0 * 0.25) */
|
|
1.18920711500272106672, /* 2 ^ (1 * 0.25) */
|
|
M_SQRT2 , /* 2 ^ (2 * 0.25) */
|
|
1.68179283050742908606, /* 2 ^ (3 * 0.25) */
|
|
};
|
|
static double pow43_lut[16];
|
|
double exp2_base = 2.11758236813575084767080625169910490512847900390625e-22; // 2^(-72)
|
|
double exp2_val;
|
|
double pow43_val = 0;
|
|
for (i = 0; i < 16; ++i)
|
|
pow43_lut[i] = i * cbrt(i);
|
|
|
|
for (i = 1; i < TABLE_4_3_SIZE; i++) {
|
|
double f, fm;
|
|
int e, m;
|
|
double value = i / 4;
|
|
if ((i & 3) == 0)
|
|
pow43_val = value / IMDCT_SCALAR * cbrt(value);
|
|
f = pow43_val * exp2_lut[i & 3];
|
|
fm = frexp(f, &e);
|
|
m = llrint(fm * (1LL << 31));
|
|
e += FRAC_BITS - 31 + 5 - 100;
|
|
|
|
/* normalized to FRAC_BITS */
|
|
table_4_3_value[i] = m;
|
|
table_4_3_exp[i] = -e;
|
|
}
|
|
for (exponent = 0; exponent < 512; exponent++) {
|
|
if (exponent && (exponent & 3) == 0)
|
|
exp2_base *= 2;
|
|
exp2_val = exp2_base * exp2_lut[exponent & 3] / IMDCT_SCALAR;
|
|
for (value = 0; value < 16; value++) {
|
|
double f = pow43_lut[value] * exp2_val;
|
|
expval_table_fixed[exponent][value] = (f < 0xFFFFFFFF ? llrint(f) : 0xFFFFFFFF);
|
|
expval_table_float[exponent][value] = f;
|
|
}
|
|
exp_table_fixed[exponent] = expval_table_fixed[exponent][1];
|
|
exp_table_float[exponent] = expval_table_float[exponent][1];
|
|
}
|
|
}
|
|
#endif /* CONFIG_HARDCODED_TABLES */
|
|
|
|
#endif /* AVCODEC_MPEGAUDIO_TABLEGEN_H */
|