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72 lines
2.3 KiB
72 lines
2.3 KiB
/* |
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* Header file for hardcoded shared mpegaudiodec tables |
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* |
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* Copyright (c) 2009 Reimar Döffinger <Reimar.Doeffinger@gmx.de> |
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* Copyright (c) 2020 Andreas Rheinhardt <andreas.rheinhardt@gmail.com> |
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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_MPEGAUDIODEC_COMMON_TABLEGEN_H |
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#define AVCODEC_MPEGAUDIODEC_COMMON_TABLEGEN_H |
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#include <stdint.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 mpegaudiodec_common_tableinit() |
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#include "libavcodec/mpegaudiodec_common_tables.h" |
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#else |
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#include <math.h> |
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#include "libavutil/attributes.h" |
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int8_t ff_table_4_3_exp [TABLE_4_3_SIZE]; |
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uint32_t ff_table_4_3_value[TABLE_4_3_SIZE]; |
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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 mpegaudiodec_common_tableinit(void) |
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{ |
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static const double exp2_lut[4] = { |
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1.00000000000000000000, /* 2 ^ (0 * 0.25) */ |
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1.18920711500272106672, /* 2 ^ (1 * 0.25) */ |
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M_SQRT2 , /* 2 ^ (2 * 0.25) */ |
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1.68179283050742908606, /* 2 ^ (3 * 0.25) */ |
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}; |
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double pow43_val = 0; |
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for (int i = 1; i < TABLE_4_3_SIZE; i++) { |
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double f, fm; |
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int e, m; |
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double value = i / 4; |
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if ((i & 3) == 0) |
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pow43_val = value / IMDCT_SCALAR * cbrt(value); |
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f = pow43_val * exp2_lut[i & 3]; |
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fm = frexp(f, &e); |
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m = llrint(fm * (1LL << 31)); |
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e += FRAC_BITS - 31 + 5 - 100; |
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/* normalized to FRAC_BITS */ |
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ff_table_4_3_value[i] = m; |
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ff_table_4_3_exp [i] = -e; |
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} |
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} |
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#endif /* CONFIG_HARDCODED_TABLES */ |
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#endif /* AVCODEC_MPEGAUDIODEC_COMMON_TABLEGEN_H */
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