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80 lines
2.2 KiB
80 lines
2.2 KiB
/* |
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* E-AC-3 decoder |
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* Copyright (c) 2007 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com> |
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* Copyright (c) 2008 Justin Ruggles |
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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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#include "avcodec.h" |
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#include "ac3.h" |
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#include "ac3_parser.h" |
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#include "ac3dec.h" |
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#include "ac3dec_data.h" |
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/** gain adaptive quantization mode */ |
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typedef enum { |
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EAC3_GAQ_NO =0, |
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EAC3_GAQ_12, |
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EAC3_GAQ_14, |
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EAC3_GAQ_124 |
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} EAC3GaqMode; |
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#define EAC3_SR_CODE_REDUCED 3 |
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/** lrint(M_SQRT2*cos(2*M_PI/12)*(1<<23)) */ |
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#define COEFF_0 10273905LL |
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/** lrint(M_SQRT2*cos(0*M_PI/12)*(1<<23)) = lrint(M_SQRT2*(1<<23)) */ |
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#define COEFF_1 11863283LL |
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/** lrint(M_SQRT2*cos(5*M_PI/12)*(1<<23)) */ |
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#define COEFF_2 3070444LL |
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/** |
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* Calculate 6-point IDCT of the pre-mantissas. |
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* All calculations are 24-bit fixed-point. |
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*/ |
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static void idct6(int pre_mant[6]) |
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{ |
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int tmp; |
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int even0, even1, even2, odd0, odd1, odd2; |
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odd1 = pre_mant[1] - pre_mant[3] - pre_mant[5]; |
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even2 = ( pre_mant[2] * COEFF_0) >> 23; |
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tmp = ( pre_mant[4] * COEFF_1) >> 23; |
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odd0 = ((pre_mant[1] + pre_mant[5]) * COEFF_2) >> 23; |
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even0 = pre_mant[0] + (tmp >> 1); |
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even1 = pre_mant[0] - tmp; |
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tmp = even0; |
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even0 = tmp + even2; |
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even2 = tmp - even2; |
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tmp = odd0; |
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odd0 = tmp + pre_mant[1] + pre_mant[3]; |
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odd2 = tmp + pre_mant[5] - pre_mant[3]; |
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pre_mant[0] = even0 + odd0; |
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pre_mant[1] = even1 + odd1; |
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pre_mant[2] = even2 + odd2; |
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pre_mant[3] = even2 - odd2; |
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pre_mant[4] = even1 - odd1; |
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pre_mant[5] = even0 - odd0; |
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}
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