253 lines
8.9 KiB
C
253 lines
8.9 KiB
C
/*
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* bit_allocate.c
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*
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* Copyright (C) Aaron Holtzman - May 1999
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*
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* This file is part of ac3dec, a free Dolby AC-3 stream decoder.
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*
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* ac3dec is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* ac3dec 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNU Make; see the file COPYING. If not, write to
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* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*/
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#include "../common.h"
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#include "ac3.h"
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#include "ac3_internal.h"
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static int hthtab[3][50] = {
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{0x730, 0x730, 0x7c0, 0x800, 0x820, 0x840, 0x850, 0x850, 0x860, 0x860,
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0x860, 0x860, 0x860, 0x870, 0x870, 0x870, 0x880, 0x880, 0x890, 0x890,
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0x8a0, 0x8a0, 0x8b0, 0x8b0, 0x8c0, 0x8c0, 0x8d0, 0x8e0, 0x8f0, 0x900,
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0x910, 0x910, 0x910, 0x910, 0x900, 0x8f0, 0x8c0, 0x870, 0x820, 0x7e0,
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0x7a0, 0x770, 0x760, 0x7a0, 0x7c0, 0x7c0, 0x6e0, 0x400, 0x3c0, 0x3c0},
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{0x710, 0x710, 0x7a0, 0x7f0, 0x820, 0x830, 0x840, 0x850, 0x850, 0x860,
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0x860, 0x860, 0x860, 0x860, 0x870, 0x870, 0x870, 0x880, 0x880, 0x880,
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0x890, 0x890, 0x8a0, 0x8a0, 0x8b0, 0x8b0, 0x8c0, 0x8c0, 0x8e0, 0x8f0,
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0x900, 0x910, 0x910, 0x910, 0x910, 0x900, 0x8e0, 0x8b0, 0x870, 0x820,
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0x7e0, 0x7b0, 0x760, 0x770, 0x7a0, 0x7c0, 0x780, 0x5d0, 0x3c0, 0x3c0},
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{0x680, 0x680, 0x750, 0x7b0, 0x7e0, 0x810, 0x820, 0x830, 0x840, 0x850,
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0x850, 0x850, 0x860, 0x860, 0x860, 0x860, 0x860, 0x860, 0x860, 0x860,
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0x870, 0x870, 0x870, 0x870, 0x880, 0x880, 0x880, 0x890, 0x8a0, 0x8b0,
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0x8c0, 0x8d0, 0x8e0, 0x8f0, 0x900, 0x910, 0x910, 0x910, 0x900, 0x8f0,
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0x8d0, 0x8b0, 0x840, 0x7f0, 0x790, 0x760, 0x7a0, 0x7c0, 0x7b0, 0x720}
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};
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static int8_t baptab[305] = {
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16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
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16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
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16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
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16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
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16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16,
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16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, // 93 padding entries
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16, 16, 16, 16, 16, 16, 16, 16, 16, 14, 14, 14, 14, 14, 14, 14,
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14, 12, 12, 12, 12, 11, 11, 11, 11, 10, 10, 10, 10, 9, 9, 9,
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9, 8, 8, 8, 8, 7, 7, 7, 7, 6, 6, 6, 6, 5, 5, 5,
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5, 4, 4, -3, -3, 3, 3, 3, -2, -2, -1, -1, -1, -1, -1, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0 // 148 padding entries
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};
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static int bndtab[30] = {21, 22, 23, 24, 25, 26, 27, 28, 31, 34,
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37, 40, 43, 46, 49, 55, 61, 67, 73, 79,
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85, 97, 109, 121, 133, 157, 181, 205, 229, 253};
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static int8_t latab[256] = {
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-64, -63, -62, -61, -60, -59, -58, -57, -56, -55, -54, -53,
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-52, -52, -51, -50, -49, -48, -47, -47, -46, -45, -44, -44,
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-43, -42, -41, -41, -40, -39, -38, -38, -37, -36, -36, -35,
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-35, -34, -33, -33, -32, -32, -31, -30, -30, -29, -29, -28,
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-28, -27, -27, -26, -26, -25, -25, -24, -24, -23, -23, -22,
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-22, -21, -21, -21, -20, -20, -19, -19, -19, -18, -18, -18,
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-17, -17, -17, -16, -16, -16, -15, -15, -15, -14, -14, -14,
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-13, -13, -13, -13, -12, -12, -12, -12, -11, -11, -11, -11,
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-10, -10, -10, -10, -10, -9, -9, -9, -9, -9, -8, -8,
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-8, -8, -8, -8, -7, -7, -7, -7, -7, -7, -6, -6,
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-6, -6, -6, -6, -6, -6, -5, -5, -5, -5, -5, -5,
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-5, -5, -4, -4, -4, -4, -4, -4, -4, -4, -4, -4,
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-4, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3,
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-3, -3, -3, -2, -2, -2, -2, -2, -2, -2, -2, -2,
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-2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0
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};
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#define UPDATE_LEAK() \
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do { \
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fastleak += fdecay; \
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if (fastleak > psd + fgain) \
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fastleak = psd + fgain; \
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slowleak += sdecay; \
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if (slowleak > psd + sgain) \
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slowleak = psd + sgain; \
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} while (0)
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#define COMPUTE_MASK() \
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do { \
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if (psd > dbknee) \
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mask -= (psd - dbknee) >> 2; \
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if (mask > hth [i >> halfrate]) \
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mask = hth [i >> halfrate]; \
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mask -= snroffset + 128 * deltba[i]; \
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mask = (mask > 0) ? 0 : ((-mask) >> 5); \
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mask -= floor; \
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} while (0)
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void bit_allocate (ac3_state_t * state, ac3_ba_t * ba, int bndstart,
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int start, int end, int fastleak, int slowleak,
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uint8_t * exp, int8_t * bap)
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{
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static int slowgain[4] = {0x540, 0x4d8, 0x478, 0x410};
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static int dbpbtab[4] = {0xc00, 0x500, 0x300, 0x100};
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static int floortab[8] = {0x910, 0x950, 0x990, 0x9d0,
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0xa10, 0xa90, 0xb10, 0x1400};
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int i, j;
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int fdecay, fgain, sdecay, sgain, dbknee, floor, snroffset;
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int psd, mask;
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int8_t * deltba;
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int * hth;
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int halfrate;
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halfrate = state->halfrate;
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fdecay = (63 + 20 * state->fdcycod) >> halfrate;
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fgain = 128 + 128 * ba->fgaincod;
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sdecay = (15 + 2 * state->sdcycod) >> halfrate;
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sgain = slowgain[state->sgaincod];
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dbknee = dbpbtab[state->dbpbcod];
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hth = hthtab[state->fscod];
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/*
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* if there is no delta bit allocation, make deltba point to an area
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* known to contain zeroes. baptab+156 here.
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*/
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deltba = (ba->deltbae == DELTA_BIT_NONE) ? baptab + 156 : ba->deltba;
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floor = floortab[state->floorcod];
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snroffset = 960 - 64 * state->csnroffst - 4 * ba->fsnroffst + floor;
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floor >>= 5;
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i = bndstart;
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j = start;
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if (start == 0) { // not the coupling channel
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int lowcomp;
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lowcomp = 0;
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j = end - 1;
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do {
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if (i < j) {
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if (exp[i+1] == exp[i] - 2)
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lowcomp = 384;
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else if (lowcomp && (exp[i+1] > exp[i]))
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lowcomp -= 64;
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}
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psd = 128 * exp[i];
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mask = psd + fgain + lowcomp;
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COMPUTE_MASK ();
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bap[i++] = (baptab+156)[mask + 4 * exp[i]];
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} while ((i < 3) || ((i < 7) && (exp[i] > exp[i-1])));
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fastleak = psd + fgain;
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slowleak = psd + sgain;
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while (i < 7) {
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if (i < j) {
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if (exp[i+1] == exp[i] - 2)
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lowcomp = 384;
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else if (lowcomp && (exp[i+1] > exp[i]))
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lowcomp -= 64;
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}
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psd = 128 * exp[i];
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UPDATE_LEAK ();
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mask = ((fastleak + lowcomp < slowleak) ?
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fastleak + lowcomp : slowleak);
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COMPUTE_MASK ();
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bap[i++] = (baptab+156)[mask + 4 * exp[i]];
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}
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if (end == 7) // lfe channel
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return;
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do {
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if (exp[i+1] == exp[i] - 2)
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lowcomp = 320;
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else if (lowcomp && (exp[i+1] > exp[i]))
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lowcomp -= 64;
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psd = 128 * exp[i];
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UPDATE_LEAK ();
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mask = ((fastleak + lowcomp < slowleak) ?
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fastleak + lowcomp : slowleak);
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COMPUTE_MASK ();
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bap[i++] = (baptab+156)[mask + 4 * exp[i]];
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} while (i < 20);
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while (lowcomp > 128) { // two iterations maximum
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lowcomp -= 128;
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psd = 128 * exp[i];
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UPDATE_LEAK ();
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mask = ((fastleak + lowcomp < slowleak) ?
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fastleak + lowcomp : slowleak);
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COMPUTE_MASK ();
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bap[i++] = (baptab+156)[mask + 4 * exp[i]];
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}
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j = i;
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}
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do {
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int startband, endband;
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startband = j;
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endband = ((bndtab-20)[i] < end) ? (bndtab-20)[i] : end;
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psd = 128 * exp[j++];
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while (j < endband) {
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int next, delta;
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next = 128 * exp[j++];
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delta = next - psd;
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switch (delta >> 9) {
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case -6: case -5: case -4: case -3: case -2:
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psd = next;
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break;
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case -1:
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psd = next + latab[(-delta) >> 1];
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break;
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case 0:
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psd += latab[delta >> 1];
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break;
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}
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}
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// minpsd = -289
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UPDATE_LEAK ();
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mask = (fastleak < slowleak) ? fastleak : slowleak;
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COMPUTE_MASK ();
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i++;
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j = startband;
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do {
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// max(mask+4*exp)=147=-(minpsd+fgain-deltba-snroffset)>>5+4*exp
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// min(mask+4*exp)=-156=-(sgain-deltba-snroffset)>>5
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bap[j++] = (baptab+156)[mask + 4 * exp[j]];
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} while (j < endband);
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} while (j < end);
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}
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