/* * AC-3 and E-AC-3 decoder tables * Copyright (c) 2007 Bartlomiej Wolowiec * * 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 */ /** * @file * Tables taken directly from the AC-3 spec or derived from it. */ #include "ac3dec_data.h" #include "libavutil/thread.h" /** * Table used to ungroup 3 values stored in 5 bits. * Used by bap=1 mantissas and GAQ. * ff_ac3_ungroup_3_in_5_bits_tab[i] = { i/9, (i%9)/3, (i%9)%3 } */ const uint8_t ff_ac3_ungroup_3_in_5_bits_tab[32][3] = { { 0, 0, 0 }, { 0, 0, 1 }, { 0, 0, 2 }, { 0, 1, 0 }, { 0, 1, 1 }, { 0, 1, 2 }, { 0, 2, 0 }, { 0, 2, 1 }, { 0, 2, 2 }, { 1, 0, 0 }, { 1, 0, 1 }, { 1, 0, 2 }, { 1, 1, 0 }, { 1, 1, 1 }, { 1, 1, 2 }, { 1, 2, 0 }, { 1, 2, 1 }, { 1, 2, 2 }, { 2, 0, 0 }, { 2, 0, 1 }, { 2, 0, 2 }, { 2, 1, 0 }, { 2, 1, 1 }, { 2, 1, 2 }, { 2, 2, 0 }, { 2, 2, 1 }, { 2, 2, 2 }, { 3, 0, 0 }, { 3, 0, 1 }, { 3, 0, 2 }, { 3, 1, 0 }, { 3, 1, 1 } }; /** * table for ungrouping 3 values in 7 bits. * used for exponents and bap=2 mantissas */ uint8_t ff_ac3_ungroup_3_in_7_bits_tab[128][3]; /** * Symmetrical Dequantization * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization * Tables 7.19 to 7.23 */ #define SYMMETRIC_DEQUANT(code, levels) (((code - (levels >> 1)) * (1 << 24)) / levels) /** * Ungrouped mantissa tables; the extra entry is padding to avoid range checks */ /** * Table 7.21 */ const int ff_ac3_bap3_mantissas[7 + 1] = { SYMMETRIC_DEQUANT(0, 7), SYMMETRIC_DEQUANT(1, 7), SYMMETRIC_DEQUANT(2, 7), SYMMETRIC_DEQUANT(3, 7), SYMMETRIC_DEQUANT(4, 7), SYMMETRIC_DEQUANT(5, 7), SYMMETRIC_DEQUANT(6, 7), }; /** * Table 7.23 */ const int ff_ac3_bap5_mantissas[15 + 1] = { SYMMETRIC_DEQUANT(0, 15), SYMMETRIC_DEQUANT(1, 15), SYMMETRIC_DEQUANT(2, 15), SYMMETRIC_DEQUANT(3, 15), SYMMETRIC_DEQUANT(4, 15), SYMMETRIC_DEQUANT(5, 15), SYMMETRIC_DEQUANT(6, 15), SYMMETRIC_DEQUANT(7, 15), SYMMETRIC_DEQUANT(8, 15), SYMMETRIC_DEQUANT(9, 15), SYMMETRIC_DEQUANT(10, 15), SYMMETRIC_DEQUANT(11, 15), SYMMETRIC_DEQUANT(12, 15), SYMMETRIC_DEQUANT(13, 15), SYMMETRIC_DEQUANT(14, 15), }; int ff_ac3_bap1_mantissas[32][3]; int ff_ac3_bap2_mantissas[128][3]; int ff_ac3_bap4_mantissas[128][2]; static inline int symmetric_dequant(int code, int levels) { return SYMMETRIC_DEQUANT(code, levels); } static av_cold void ac3_init_static(void) { /* generate table for ungrouping 3 values in 7 bits reference: Section 7.1.3 Exponent Decoding */ for (int i = 0; i < 128; ++i) { ff_ac3_ungroup_3_in_7_bits_tab[i][0] = i / 25; ff_ac3_ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5; ff_ac3_ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5; } /* generate grouped mantissa tables reference: Section 7.3.5 Ungrouping of Mantissas */ for (int i = 0; i < 32; ++i) { /* bap=1 mantissas */ ff_ac3_bap1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3); ff_ac3_bap1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3); ff_ac3_bap1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3); } for (int i = 0; i < 128; ++i) { /* bap=2 mantissas */ ff_ac3_bap2_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_7_bits_tab[i][0], 5); ff_ac3_bap2_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_7_bits_tab[i][1], 5); ff_ac3_bap2_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_7_bits_tab[i][2], 5); /* bap=4 mantissas */ ff_ac3_bap4_mantissas[i][0] = symmetric_dequant(i / 11, 11); ff_ac3_bap4_mantissas[i][1] = symmetric_dequant(i % 11, 11); } } av_cold void ff_ac3_init_static(void) { static AVOnce ac3_init_static_once = AV_ONCE_INIT; ff_thread_once(&ac3_init_static_once, ac3_init_static); } /** * Quantization table: levels for symmetric. bits for asymmetric. * reference: Table 7.18 Mapping of bap to Quantizer */ const uint8_t ff_ac3_quantization_tab[16] = { 0, 3, 5, 7, 11, 15, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16 }; /** * Table for default stereo downmixing coefficients * reference: Section 7.8.2 Downmixing Into Two Channels */ const uint8_t ff_ac3_default_coeffs[8][5][2] = { { { 2, 7 }, { 7, 2 }, }, { { 4, 4 }, }, { { 2, 7 }, { 7, 2 }, }, { { 2, 7 }, { 5, 5 }, { 7, 2 }, }, { { 2, 7 }, { 7, 2 }, { 6, 6 }, }, { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, }, { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, }, { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, }, }; const uint8_t ff_eac3_hebap_tab[64] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 8, 8, 8, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 19, 19, 19, 19, 19, 19, 19, 19, 19, }; /** * Table E2.15 Default Spectral Extension Banding Structure */ const uint8_t ff_eac3_default_spx_band_struct[17] = { 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1 }; /** Adjustments in dB gain (LFE, +10 to -21 dB) */ const float ff_eac3_gain_levels_lfe[32] = { 3.162275, 2.818382, 2.511886, 2.238719, 1.995261, 1.778278, 1.584893, 1.412536, 1.258924, 1.122018, 1.000000, 0.891251, 0.794328, 0.707946, 0.630957, 0.562341, 0.501187, 0.446683, 0.398107, 0.354813, 0.316227, 0.281838, 0.251188, 0.223872, 0.199526, 0.177828, 0.158489, 0.141253, 0.125892, 0.112201, 0.100000, 0.089125 };