1/* 2 * Common code between the AC-3 encoder and decoder 3 * Copyright (c) 2000 Fabrice Bellard 4 * 5 * This file is part of FFmpeg. 6 * 7 * FFmpeg is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU Lesser General Public 9 * License as published by the Free Software Foundation; either 10 * version 2.1 of the License, or (at your option) any later version. 11 * 12 * FFmpeg is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 * Lesser General Public License for more details. 16 * 17 * You should have received a copy of the GNU Lesser General Public 18 * License along with FFmpeg; if not, write to the Free Software 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 20 */ 21 22/** 23 * @file 24 * Common code between the AC-3 encoder and decoder. 25 */ 26 27#include "libavutil/error.h" 28#include "libavutil/macros.h" 29 30#include "ac3.h" 31#include "ac3defs.h" 32 33/** 34 * Starting frequency coefficient bin for each critical band. 35 */ 36const uint8_t ff_ac3_band_start_tab[AC3_CRITICAL_BANDS+1] = { 37 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 38 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 39 20, 21, 22, 23, 24, 25, 26, 27, 28, 31, 40 34, 37, 40, 43, 46, 49, 55, 61, 67, 73, 41 79, 85, 97, 109, 121, 133, 157, 181, 205, 229, 253 42}; 43 44/** 45 * Map each frequency coefficient bin to the critical band that contains it. 46 */ 47const uint8_t ff_ac3_bin_to_band_tab[253] = { 48 0, 49 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 50 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 51 25, 26, 27, 28, 28, 28, 29, 29, 29, 30, 30, 30, 52 31, 31, 31, 32, 32, 32, 33, 33, 33, 34, 34, 34, 53 35, 35, 35, 35, 35, 35, 36, 36, 36, 36, 36, 36, 54 37, 37, 37, 37, 37, 37, 38, 38, 38, 38, 38, 38, 55 39, 39, 39, 39, 39, 39, 40, 40, 40, 40, 40, 40, 56 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 41, 57 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 42, 58 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 43, 59 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 44, 60 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 61 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 45, 62 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 63 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 46, 64 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 65 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 47, 66 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 67 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 48, 68 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 69 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49 70}; 71 72static const uint8_t ac3_log_add_tab[260]= { 730x40,0x3f,0x3e,0x3d,0x3c,0x3b,0x3a,0x39,0x38,0x37, 740x36,0x35,0x34,0x34,0x33,0x32,0x31,0x30,0x2f,0x2f, 750x2e,0x2d,0x2c,0x2c,0x2b,0x2a,0x29,0x29,0x28,0x27, 760x26,0x26,0x25,0x24,0x24,0x23,0x23,0x22,0x21,0x21, 770x20,0x20,0x1f,0x1e,0x1e,0x1d,0x1d,0x1c,0x1c,0x1b, 780x1b,0x1a,0x1a,0x19,0x19,0x18,0x18,0x17,0x17,0x16, 790x16,0x15,0x15,0x15,0x14,0x14,0x13,0x13,0x13,0x12, 800x12,0x12,0x11,0x11,0x11,0x10,0x10,0x10,0x0f,0x0f, 810x0f,0x0e,0x0e,0x0e,0x0d,0x0d,0x0d,0x0d,0x0c,0x0c, 820x0c,0x0c,0x0b,0x0b,0x0b,0x0b,0x0a,0x0a,0x0a,0x0a, 830x0a,0x09,0x09,0x09,0x09,0x09,0x08,0x08,0x08,0x08, 840x08,0x08,0x07,0x07,0x07,0x07,0x07,0x07,0x06,0x06, 850x06,0x06,0x06,0x06,0x06,0x06,0x05,0x05,0x05,0x05, 860x05,0x05,0x05,0x05,0x04,0x04,0x04,0x04,0x04,0x04, 870x04,0x04,0x04,0x04,0x04,0x03,0x03,0x03,0x03,0x03, 880x03,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x03,0x02, 890x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02, 900x02,0x02,0x02,0x02,0x02,0x02,0x02,0x02,0x01,0x01, 910x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01, 920x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01, 930x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01, 940x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, 950x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, 960x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, 970x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, 980x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, 99}; 100 101static const uint16_t ac3_hearing_threshold_tab[AC3_CRITICAL_BANDS][3]= { 102{ 0x04d0,0x04f0,0x0580 }, 103{ 0x04d0,0x04f0,0x0580 }, 104{ 0x0440,0x0460,0x04b0 }, 105{ 0x0400,0x0410,0x0450 }, 106{ 0x03e0,0x03e0,0x0420 }, 107{ 0x03c0,0x03d0,0x03f0 }, 108{ 0x03b0,0x03c0,0x03e0 }, 109{ 0x03b0,0x03b0,0x03d0 }, 110{ 0x03a0,0x03b0,0x03c0 }, 111{ 0x03a0,0x03a0,0x03b0 }, 112{ 0x03a0,0x03a0,0x03b0 }, 113{ 0x03a0,0x03a0,0x03b0 }, 114{ 0x03a0,0x03a0,0x03a0 }, 115{ 0x0390,0x03a0,0x03a0 }, 116{ 0x0390,0x0390,0x03a0 }, 117{ 0x0390,0x0390,0x03a0 }, 118{ 0x0380,0x0390,0x03a0 }, 119{ 0x0380,0x0380,0x03a0 }, 120{ 0x0370,0x0380,0x03a0 }, 121{ 0x0370,0x0380,0x03a0 }, 122{ 0x0360,0x0370,0x0390 }, 123{ 0x0360,0x0370,0x0390 }, 124{ 0x0350,0x0360,0x0390 }, 125{ 0x0350,0x0360,0x0390 }, 126{ 0x0340,0x0350,0x0380 }, 127{ 0x0340,0x0350,0x0380 }, 128{ 0x0330,0x0340,0x0380 }, 129{ 0x0320,0x0340,0x0370 }, 130{ 0x0310,0x0320,0x0360 }, 131{ 0x0300,0x0310,0x0350 }, 132{ 0x02f0,0x0300,0x0340 }, 133{ 0x02f0,0x02f0,0x0330 }, 134{ 0x02f0,0x02f0,0x0320 }, 135{ 0x02f0,0x02f0,0x0310 }, 136{ 0x0300,0x02f0,0x0300 }, 137{ 0x0310,0x0300,0x02f0 }, 138{ 0x0340,0x0320,0x02f0 }, 139{ 0x0390,0x0350,0x02f0 }, 140{ 0x03e0,0x0390,0x0300 }, 141{ 0x0420,0x03e0,0x0310 }, 142{ 0x0460,0x0420,0x0330 }, 143{ 0x0490,0x0450,0x0350 }, 144{ 0x04a0,0x04a0,0x03c0 }, 145{ 0x0460,0x0490,0x0410 }, 146{ 0x0440,0x0460,0x0470 }, 147{ 0x0440,0x0440,0x04a0 }, 148{ 0x0520,0x0480,0x0460 }, 149{ 0x0800,0x0630,0x0440 }, 150{ 0x0840,0x0840,0x0450 }, 151{ 0x0840,0x0840,0x04e0 }, 152}; 153 154static inline int calc_lowcomp1(int a, int b0, int b1, int c) 155{ 156 if ((b0 + 256) == b1) { 157 a = c; 158 } else if (b0 > b1) { 159 a = FFMAX(a - 64, 0); 160 } 161 return a; 162} 163 164static inline int calc_lowcomp(int a, int b0, int b1, int bin) 165{ 166 if (bin < 7) { 167 return calc_lowcomp1(a, b0, b1, 384); 168 } else if (bin < 20) { 169 return calc_lowcomp1(a, b0, b1, 320); 170 } else { 171 return FFMAX(a - 128, 0); 172 } 173} 174 175void ff_ac3_bit_alloc_calc_psd(int8_t *exp, int start, int end, int16_t *psd, 176 int16_t *band_psd) 177{ 178 int bin, band; 179 180 /* exponent mapping to PSD */ 181 for (bin = start; bin < end; bin++) { 182 psd[bin]=(3072 - (exp[bin] << 7)); 183 } 184 185 /* PSD integration */ 186 bin = start; 187 band = ff_ac3_bin_to_band_tab[start]; 188 do { 189 int v = psd[bin++]; 190 int band_end = FFMIN(ff_ac3_band_start_tab[band+1], end); 191 for (; bin < band_end; bin++) { 192 int max = FFMAX(v, psd[bin]); 193 /* logadd */ 194 int adr = FFMIN(max - ((v + psd[bin] + 1) >> 1), 255); 195 v = max + ac3_log_add_tab[adr]; 196 } 197 band_psd[band++] = v; 198 } while (end > ff_ac3_band_start_tab[band]); 199} 200 201int ff_ac3_bit_alloc_calc_mask(AC3BitAllocParameters *s, int16_t *band_psd, 202 int start, int end, int fast_gain, int is_lfe, 203 int dba_mode, int dba_nsegs, uint8_t *dba_offsets, 204 uint8_t *dba_lengths, uint8_t *dba_values, 205 int16_t *mask) 206{ 207 int16_t excite[AC3_CRITICAL_BANDS]; /* excitation */ 208 int band; 209 int band_start, band_end, begin, end1; 210 int lowcomp, fastleak, slowleak; 211 212 if (end <= 0) 213 return AVERROR_INVALIDDATA; 214 215 /* excitation function */ 216 band_start = ff_ac3_bin_to_band_tab[start]; 217 band_end = ff_ac3_bin_to_band_tab[end-1] + 1; 218 219 if (band_start == 0) { 220 lowcomp = 0; 221 lowcomp = calc_lowcomp1(lowcomp, band_psd[0], band_psd[1], 384); 222 excite[0] = band_psd[0] - fast_gain - lowcomp; 223 lowcomp = calc_lowcomp1(lowcomp, band_psd[1], band_psd[2], 384); 224 excite[1] = band_psd[1] - fast_gain - lowcomp; 225 begin = 7; 226 for (band = 2; band < 7; band++) { 227 if (!(is_lfe && band == 6)) 228 lowcomp = calc_lowcomp1(lowcomp, band_psd[band], band_psd[band+1], 384); 229 fastleak = band_psd[band] - fast_gain; 230 slowleak = band_psd[band] - s->slow_gain; 231 excite[band] = fastleak - lowcomp; 232 if (!(is_lfe && band == 6)) { 233 if (band_psd[band] <= band_psd[band+1]) { 234 begin = band + 1; 235 break; 236 } 237 } 238 } 239 240 end1 = FFMIN(band_end, 22); 241 for (band = begin; band < end1; band++) { 242 if (!(is_lfe && band == 6)) 243 lowcomp = calc_lowcomp(lowcomp, band_psd[band], band_psd[band+1], band); 244 fastleak = FFMAX(fastleak - s->fast_decay, band_psd[band] - fast_gain); 245 slowleak = FFMAX(slowleak - s->slow_decay, band_psd[band] - s->slow_gain); 246 excite[band] = FFMAX(fastleak - lowcomp, slowleak); 247 } 248 begin = 22; 249 } else { 250 /* coupling channel */ 251 begin = band_start; 252 fastleak = (s->cpl_fast_leak << 8) + 768; 253 slowleak = (s->cpl_slow_leak << 8) + 768; 254 } 255 256 for (band = begin; band < band_end; band++) { 257 fastleak = FFMAX(fastleak - s->fast_decay, band_psd[band] - fast_gain); 258 slowleak = FFMAX(slowleak - s->slow_decay, band_psd[band] - s->slow_gain); 259 excite[band] = FFMAX(fastleak, slowleak); 260 } 261 262 /* compute masking curve */ 263 264 for (band = band_start; band < band_end; band++) { 265 int tmp = s->db_per_bit - band_psd[band]; 266 if (tmp > 0) { 267 excite[band] += tmp >> 2; 268 } 269 mask[band] = FFMAX(ac3_hearing_threshold_tab[band >> s->sr_shift][s->sr_code], excite[band]); 270 } 271 272 /* delta bit allocation */ 273 274 if (dba_mode == DBA_REUSE || dba_mode == DBA_NEW) { 275 int i, seg, delta; 276 if (dba_nsegs > 8) 277 return -1; 278 band = band_start; 279 for (seg = 0; seg < dba_nsegs; seg++) { 280 band += dba_offsets[seg]; 281 if (band >= AC3_CRITICAL_BANDS || dba_lengths[seg] > AC3_CRITICAL_BANDS-band) 282 return -1; 283 if (dba_values[seg] >= 4) { 284 delta = (dba_values[seg] - 3) * 128; 285 } else { 286 delta = (dba_values[seg] - 4) * 128; 287 } 288 for (i = 0; i < dba_lengths[seg]; i++) { 289 mask[band++] += delta; 290 } 291 } 292 } 293 return 0; 294} 295