1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300
|
/*
* TwoLAME: an optimized MPEG Audio Layer Two encoder
*
* Copyright (C) 2001-2004 Michael Cheng
* Copyright (C) 2004-2006 The TwoLAME Project
*
* This library 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.
*
* This library 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 this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id$
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "twolame.h"
#include "common.h"
#include "bitbuffer.h"
#include "availbits.h"
#include "encode.h"
#include "bitbuffer_inline.h"
static const FLOAT multiple[64] = {
2.00000000000000, 1.58740105196820, 1.25992104989487,
1.00000000000000, 0.79370052598410, 0.62996052494744, 0.50000000000000,
0.39685026299205, 0.31498026247372, 0.25000000000000, 0.19842513149602,
0.15749013123686, 0.12500000000000, 0.09921256574801, 0.07874506561843,
0.06250000000000, 0.04960628287401, 0.03937253280921, 0.03125000000000,
0.02480314143700, 0.01968626640461, 0.01562500000000, 0.01240157071850,
0.00984313320230, 0.00781250000000, 0.00620078535925, 0.00492156660115,
0.00390625000000, 0.00310039267963, 0.00246078330058, 0.00195312500000,
0.00155019633981, 0.00123039165029, 0.00097656250000, 0.00077509816991,
0.00061519582514, 0.00048828125000, 0.00038754908495, 0.00030759791257,
0.00024414062500, 0.00019377454248, 0.00015379895629, 0.00012207031250,
0.00009688727124, 0.00007689947814, 0.00006103515625, 0.00004844363562,
0.00003844973907, 0.00003051757813, 0.00002422181781, 0.00001922486954,
0.00001525878906, 0.00001211090890, 0.00000961243477, 0.00000762939453,
0.00000605545445, 0.00000480621738, 0.00000381469727, 0.00000302772723,
0.00000240310869, 0.00000190734863, 0.00000151386361, 0.00000120155435,
1E-20
};
/* MFC May03
Gosh. I should really document this mess.
This is a compact data format for all the info that is
in the bit allocation tables in the mpeg standards.
All the allocation tables are here. There is just multiple
redirections to find the number that you want.
I might have to reduce the number of index tables to make the code
more readable.
*/
#define NUMTABLES 5
/* There are really only 9 distinct lines in the allocation tables
each member of this table is an index into */
/* step_index[linenumber][index] */
static const int step_index[9][16] = {
/* 0 */ {0, 1, 3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17},
/* 1 */ {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 17},
/* 2 */ {0, 1, 2, 3, 4, 5, 6, 17, 0, 0, 0, 0, 0, 0, 0, 0},
/* 3 */ {0, 1, 2, 17, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
/* 4 */ {0, 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16},
/* 5 */ {0, 1, 2, 4, 5, 6, 7, 8, 0, 0, 0, 0, 0, 0, 0, 0},
/* From ISO13818 Table B.1 */
/* 6 */ {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15},
/* 7 */ {0, 1, 2, 4, 5, 6, 7, 8, 0, 0, 0, 0, 0, 0, 0, 0},
/* 8 */ {0, 1, 2, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
};
static const int nbal[9] = { 4, 4, 3, 2, 4, 3, 4, 3, 2 };
/* 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 */
/* The number of steps allowed */
static const int steps[18] =
{ 0, 3, 5, 7, 9, 15, 31, 63, 127, 255, 511, 1023, 2047, 4095, 8191, 16383, 32767, 65535 };
/* The power of 2 just under the steps value */
static const int steps2n[18] =
{ 0, 2, 4, 4, 8, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768 };
/* The bits per codeword from TableB.4 */
static const int bits[18] = { 0, 5, 7, 3, 10, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
/* Samples per codeword Table B.4 Page 53 */
//static int group[18] = {0, 3, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
static const int group[18] = { 0, 1, 1, 3, 1, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3 };
/* nbal */
/* The sblimits of the 5 allocation tables
4 tables for MPEG-1
1 table for MPEG-2 LSF */
static const int table_sblimit[5] = { 27, 30, 8, 12, 30 };
/* Each table contains a list of allowable quantization steps.
There are only 9 distinct lists of steps.
This table gives the index of which of the 9 lists is being used
A "-1" entry means that it is above the sblimit for this table */
static const int line[5][SBLIMIT] = {
/* 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
31 */
{0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, -1, -1, -1,
-1, -1},
{0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, -1,
-1},
{4, 4, 5, 5, 5, 5, 5, 5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1},
{4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1},
/* LSF Table */
{6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8}
};
/* This is ISO11172 Table B.1 */
static const FLOAT scalefactor[64] = { /* Equation for nth element = 2 / (cuberoot(2) ^ n) */
2.00000000000000, 1.58740105196820, 1.25992104989487,
1.00000000000000, 0.79370052598410, 0.62996052494744, 0.50000000000000,
0.39685026299205, 0.31498026247372, 0.25000000000000, 0.19842513149602,
0.15749013123686, 0.12500000000000, 0.09921256574801, 0.07874506561843,
0.06250000000000, 0.04960628287401, 0.03937253280921, 0.03125000000000,
0.02480314143700, 0.01968626640461, 0.01562500000000, 0.01240157071850,
0.00984313320230, 0.00781250000000, 0.00620078535925, 0.00492156660115,
0.00390625000000, 0.00310039267963, 0.00246078330058, 0.00195312500000,
0.00155019633981, 0.00123039165029, 0.00097656250000, 0.00077509816991,
0.00061519582514, 0.00048828125000, 0.00038754908495, 0.00030759791257,
0.00024414062500, 0.00019377454248, 0.00015379895629, 0.00012207031250,
0.00009688727124, 0.00007689947814, 0.00006103515625, 0.00004844363562,
0.00003844973907, 0.00003051757813, 0.00002422181781, 0.00001922486954,
0.00001525878906, 0.00001211090890, 0.00000961243477, 0.00000762939453,
0.00000605545445, 0.00000480621738, 0.00000381469727, 0.00000302772723,
0.00000240310869, 0.00000190734863, 0.00000151386361, 0.00000120155435,
1E-20
};
/* ISO11172 Table C.5 Layer II Signal to Noise Raios
MFC FIX find a reference for these in terms of bits->SNR value
Index into table is the steps index
index steps SNR
0 0 0.00
1 3 7.00
2 5 11.00
3 7 16.00
4 9 20.84
etc
*/
static const FLOAT SNR[18] = {
0.00, 7.00, 11.00, 16.00, 20.84, 25.28, 31.59, 37.75, 43.84,
49.89, 55.93, 61.96, 67.98, 74.01, 80.03, 86.05, 92.01, 98.01
};
static int get_js_bound(int m_ext)
{
static const int jsb_table[4] = { 4, 8, 12, 16 };
if (m_ext < 0 || m_ext > 3) {
fprintf(stderr, "get_js_bound() bad modext (%d)\n", m_ext);
return -1;
}
return (jsb_table[m_ext]);
}
int encode_init(twolame_options * glopts)
{
frame_header *header = &glopts->header;
int bsp, br_per_ch, sfrq;
bsp = header->bitrate_index;
br_per_ch = glopts->bitrate / glopts->num_channels_out;
sfrq = (int) (glopts->samplerate_out / 1000.0);
/* decision rules refer to per-channel bitrates (kbits/sec/chan) */
if (header->version == TWOLAME_MPEG1) { /* MPEG-1 */
if ((sfrq == 48 && br_per_ch >= 56)
|| (br_per_ch >= 56 && br_per_ch <= 80))
glopts->tablenum = 0;
else if (sfrq != 48 && br_per_ch >= 96)
glopts->tablenum = 1;
else if (sfrq != 32 && br_per_ch <= 48)
glopts->tablenum = 2;
else
glopts->tablenum = 3;
} else { /* MPEG-2 LSF */
glopts->tablenum = 4;
}
// glopts->sblimit = pick_table ( glopts );
/* MFC FIX this up */
glopts->sblimit = table_sblimit[glopts->tablenum];
// fprintf(stderr,"encode_init: using tablenum %i with sblimit %i\n",glopts->tablenum,
// glopts->sblimit);
if (glopts->mode == TWOLAME_JOINT_STEREO)
glopts->jsbound = get_js_bound(header->mode_ext);
else
glopts->jsbound = glopts->sblimit;
/* alloc, tab_num set in pick_table */
#define DUMPTABLESx
#ifdef DUMPTABLES
{
int tablenumber, j, sblimit, sb;
fprintf(stderr, "Tables B.21,b,c,d from ISO11172 and the LSF table from ISO13818\n");
for (tablenumber = 0; tablenumber < NUMTABLES; tablenumber++) {
/* Print Table Header */
fprintf(stderr, "Tablenum %i\n", tablenumber);
fprintf(stderr, "sb nbal ");
for (j = 0; j < 16; j++)
fprintf(stderr, "%6i ", j);
fprintf(stderr, "\n");
fprintf(stderr,
"-----------------------------------------------------------------------------------------------------------------------\n");
sblimit = table_sblimit[tablenumber];
for (sb = 0; sb < SBLIMIT; sb++) {
int thisline = line[tablenumber][sb];
fprintf(stderr, "%2i %4i ", sb, nbal[thisline]);
if (nbal[thisline] != 0) {
for (j = 0; j < (1 << nbal[thisline]); j++)
fprintf(stderr, "%6i ", steps[step_index[thisline][j]]);
}
fprintf(stderr, "\n");
}
fprintf(stderr, "\n");
}
}
#endif
// Success
return 0;
}
/*
scale_factor_calc
pick_scale
if JOINTSTEREO
combine_LR
scale_factor_calc
use psy model to determine SMR
transmission pattern
main_bit_allocation
if (error protection)
calc CRC
encode_info
if (error_protection)
encode_CRC
encode_bit_alloc
encode_scale
subband_quantization
sample_encoding
*/
void scalefactor_calc(FLOAT sb_sample[][3][SCALE_BLOCK][SBLIMIT],
unsigned int sf_index[][3][SBLIMIT], int nch, int sblimit)
{
/* Optimized to use binary search instead of linear scan through the scalefactor table;
guarantees to find scalefactor in only 5 jumps/comparisons and not in {0 (lin. best) to 63
(lin. worst)}. Scalefactors for subbands > sblimit are no longer computed. Uses a single
sblimit-loop. Patrick De Smet Oct 1999. */
int ch, gr;
/* Using '--' loops to avoid possible "cmp value + bne/beq" compiler */
/* inefficiencies. Below loops should compile to "bne/beq" only code */
for (ch = nch; ch--;)
for (gr = 3; gr--;) {
int sb;
for (sb = sblimit; sb--;) {
int j;
unsigned int l;
register FLOAT temp;
unsigned int scale_fac;
/* Determination of max. over each set of 12 subband samples: */
/* PDS TODO: maybe this could/should ??!! be integrated into */
/* the subband filtering routines? */
register FLOAT cur_max = fabs(sb_sample[ch][gr][SCALE_BLOCK - 1][sb]);
for (j = SCALE_BLOCK - 1; j--;) {
if ((temp = fabs(sb_sample[ch][gr][j][sb])) > cur_max)
cur_max = temp;
}
/* PDS: binary search in the scalefactor table: */
/* This is the real speed up: */
for (l = 16, scale_fac = 32; l; l >>= 1) {
if (cur_max <= scalefactor[scale_fac])
scale_fac += l;
else
scale_fac -= l;
}
if (cur_max > scalefactor[scale_fac])
scale_fac--;
sf_index[ch][gr][sb] = scale_fac;
/* There is a direct way of working out the index, if the maximum value is known
but since it involves a log it isn't really speedy. Items in the scalefactor[]
table are calculated by: the n'th entry = 2 / (cuberoot(2) ^ n) And so using a
bit of maths you get: index = (int)(log(2.0/cur_max) / LNCUBEROOTTWO);
fprintf(stderr,"cur_max %.14lf scalefactorindex %i multiple %.14lf\n",cur_max,
scale_fac, scalefactor[scale_fac]); */
}
}
}
/* Combine L&R channels into a mono joint stereo channel */
void combine_lr(FLOAT sb_sample[2][3][SCALE_BLOCK][SBLIMIT],
FLOAT joint_sample[3][SCALE_BLOCK][SBLIMIT], int sblimit)
{
int sb, sample, gr;
for (sb = 0; sb < sblimit; ++sb)
for (sample = 0; sample < SCALE_BLOCK; ++sample)
for (gr = 0; gr < 3; ++gr)
joint_sample[gr][sample][sb] =
.5 * (sb_sample[0][gr][sample][sb] + sb_sample[1][gr][sample][sb]);
}
/* PURPOSE:For each subband, puts the smallest scalefactor of the 3
associated with a frame into #max_sc#. This is used
used by Psychoacoustic Model I.
Someone in dist10 source code's history, somebody wrote the following:
"(I would recommend changin max_sc to min_sc)"
In psy model 1, the *maximum* out of the scale picked here and
the maximum SPL within each subband is selected. So I'd think that
a maximum here makes heaps of sense.
MFC FIX: Feb 2003 - is this only needed for psy model 1?
*/
void find_sf_max(twolame_options * glopts,
unsigned int sf_index[2][3][SBLIMIT], FLOAT sf_max[2][SBLIMIT])
{
unsigned int sb, gr, ch;
unsigned int lowest_sf_index;
unsigned int nch = glopts->num_channels_out;
unsigned int sblimit = glopts->sblimit;
for (ch = 0; ch < nch; ch++)
for (sb = 0; sb < sblimit; sb++) {
for (gr = 1, lowest_sf_index = sf_index[ch][0][sb]; gr < 3; gr++)
if (lowest_sf_index > sf_index[ch][gr][sb])
lowest_sf_index = sf_index[ch][gr][sb];
sf_max[ch][sb] = multiple[lowest_sf_index];
}
for (sb = sblimit; sb < SBLIMIT; sb++)
sf_max[0][sb] = sf_max[1][sb] = 1E-20;
}
/* sf_transmission_pattern
PURPOSE:For a given subband, determines whether to send 1, 2, or
all 3 of the scalefactors, and fills in the scalefactor
select information accordingly
This is From ISO11172 Sect C.1.5.2.5 "coding of scalefactors"
and
Table C.4 "LayerII Scalefactors Transmission Pattern"
*/
void sf_transmission_pattern(twolame_options * glopts,
unsigned int sf_index[2][3][SBLIMIT],
unsigned int sf_selectinfo[2][SBLIMIT])
{
int nch = glopts->num_channels_out;
int sblimit = glopts->sblimit;
int dscf[2];
int class[2], i, j, k;
static const int pattern[5][5] = {
{0x123, 0x122, 0x122, 0x133, 0x123},
{0x113, 0x111, 0x111, 0x444, 0x113},
{0x111, 0x111, 0x111, 0x333, 0x113},
{0x222, 0x222, 0x222, 0x333, 0x123},
{0x123, 0x122, 0x122, 0x133, 0x123}
};
for (k = 0; k < nch; k++)
for (i = 0; i < sblimit; i++) {
dscf[0] = (sf_index[k][0][i] - sf_index[k][1][i]);
dscf[1] = (sf_index[k][1][i] - sf_index[k][2][i]);
for (j = 0; j < 2; j++) {
if (dscf[j] <= -3)
class[j] = 0;
else if (dscf[j] > -3 && dscf[j] < 0)
class[j] = 1;
else if (dscf[j] == 0)
class[j] = 2;
else if (dscf[j] > 0 && dscf[j] < 3)
class[j] = 3;
else
class[j] = 4;
}
switch (pattern[class[0]][class[1]]) {
case 0x123:
sf_selectinfo[k][i] = 0;
break;
case 0x122:
sf_selectinfo[k][i] = 3;
sf_index[k][2][i] = sf_index[k][1][i];
break;
case 0x133:
sf_selectinfo[k][i] = 3;
sf_index[k][1][i] = sf_index[k][2][i];
break;
case 0x113:
sf_selectinfo[k][i] = 1;
sf_index[k][1][i] = sf_index[k][0][i];
break;
case 0x111:
sf_selectinfo[k][i] = 2;
sf_index[k][1][i] = sf_index[k][2][i] = sf_index[k][0][i];
break;
case 0x222:
sf_selectinfo[k][i] = 2;
sf_index[k][0][i] = sf_index[k][2][i] = sf_index[k][1][i];
break;
case 0x333:
sf_selectinfo[k][i] = 2;
sf_index[k][0][i] = sf_index[k][1][i] = sf_index[k][2][i];
break;
case 0x444:
sf_selectinfo[k][i] = 2;
if (sf_index[k][0][i] > sf_index[k][2][i])
sf_index[k][0][i] = sf_index[k][2][i];
sf_index[k][1][i] = sf_index[k][2][i] = sf_index[k][0][i];
break;
}
}
}
void write_header(twolame_options * glopts, bit_stream * bs)
{
frame_header *header = &glopts->header;
buffer_putbits(bs, 0xfff, 12); /* syncword 12 bits */
buffer_put1bit(bs, header->version); /* ID 1 bit */
buffer_putbits(bs, 4 - header->lay, 2); /* layer 2 bits */
buffer_put1bit(bs, !header->error_protection); /* bit set => no err prot */
buffer_putbits(bs, header->bitrate_index, 4);
buffer_putbits(bs, header->samplerate_idx, 2);
buffer_put1bit(bs, header->padding);
buffer_put1bit(bs, header->private_bit); /* private_bit */
buffer_putbits(bs, header->mode, 2);
buffer_putbits(bs, header->mode_ext, 2);
buffer_put1bit(bs, header->copyright);
buffer_put1bit(bs, header->original);
buffer_putbits(bs, header->emphasis, 2);
}
/*************************************************************************
encode_bit_alloc (Layer II)
PURPOSE: Writes bit allocation information onto bitstream
4,3,2, or 0 bits depending on the quantization table used.
************************************************************************/
void write_bit_alloc(twolame_options * glopts, unsigned int bit_alloc[2][SBLIMIT], bit_stream * bs)
{
int nch = glopts->num_channels_out;
int sblimit = glopts->sblimit;
int jsbound = glopts->jsbound;
int sb, ch;
for (sb = 0; sb < sblimit; sb++) {
if (sb < jsbound) {
for (ch = 0; ch < ((sb < jsbound) ? nch : 1); ch++) {
buffer_putbits(bs, bit_alloc[ch][sb], nbal[line[glopts->tablenum][sb]]);
glopts->num_crc_bits += nbal[line[glopts->tablenum][sb]];
}
} else {
buffer_putbits(bs, bit_alloc[0][sb], nbal[line[glopts->tablenum][sb]]);
glopts->num_crc_bits += nbal[line[glopts->tablenum][sb]];
}
}
}
/************************************************************************
write_scalefactors
PURPOSE:The encoded scalar factor information is arranged and
queued into the output fifo to be transmitted.
The three scale factors associated with
a given subband and channel are transmitted in accordance
with the scfsi, which is transmitted first.
************************************************************************/
void write_scalefactors(twolame_options * glopts,
unsigned int bit_alloc[2][SBLIMIT],
unsigned int sf_selectinfo[2][SBLIMIT],
unsigned int sf_index[2][3][SBLIMIT], bit_stream * bs)
{
int nch = glopts->num_channels_out;
int sblimit = glopts->sblimit;
int sb, gr, ch;
/* Write out the scalefactor selection information */
for (sb = 0; sb < sblimit; sb++)
for (ch = 0; ch < nch; ch++)
if (bit_alloc[ch][sb]) {
buffer_putbits(bs, sf_selectinfo[ch][sb], 2);
glopts->num_crc_bits += 2;
}
/* Write out the scalefactors */
for (sb = 0; sb < sblimit; sb++)
for (ch = 0; ch < nch; ch++)
if (bit_alloc[ch][sb]) // above jsbound, bit_alloc[0][i] == ba[1][i]
{
switch (sf_selectinfo[ch][sb]) {
case 0:
for (gr = 0; gr < 3; gr++)
buffer_putbits(bs, sf_index[ch][gr][sb], 6);
break;
case 1:
case 3:
buffer_putbits(bs, sf_index[ch][0][sb], 6);
buffer_putbits(bs, sf_index[ch][2][sb], 6);
break;
case 2:
buffer_putbits(bs, sf_index[ch][0][sb], 6);
break;
}
}
}
/* ISO11172 Table C.6 Layer II quantization co-efficients */
static const FLOAT a[18] = {
0,
0.750000000, 0.625000000, 0.875000000, 0.562500000, 0.937500000,
0.968750000, 0.984375000, 0.992187500, 0.996093750, 0.998046875,
0.999023438, 0.999511719, 0.999755859, 0.999877930, 0.999938965,
0.999969482, 0.999984741
};
static const FLOAT b[18] = {
0,
-0.250000000, -0.375000000, -0.125000000, -0.437500000, -0.062500000,
-0.031250000, -0.015625000, -0.007812500, -0.003906250, -0.001953125,
-0.000976563, -0.000488281, -0.000244141, -0.000122070, -0.000061035,
-0.000030518, -0.000015259
};
/************************************************************************
subband_quantization (Layer II)
PURPOSE:Quantizes subband samples to appropriate number of bits
SEMANTICS: Subband samples are divided by their scalefactors, which
makes the quantization more efficient. The scaled samples are
quantized by the function a*x+b, where a and b are functions of
the number of quantization levels. The result is then truncated
to the appropriate number of bits and the MSB is inverted.
Note that for fractional 2's complement, inverting the MSB for a
negative number x is equivalent to adding 1 to it.
************************************************************************/
void
subband_quantization(twolame_options * glopts,
unsigned int sf_index[2][3][SBLIMIT],
FLOAT sb_samples[2][3][SCALE_BLOCK][SBLIMIT],
unsigned int j_scale[3][SBLIMIT],
FLOAT j_samps[3][SCALE_BLOCK][SBLIMIT],
unsigned int bit_alloc[2][SBLIMIT],
unsigned int sbband[2][3][SCALE_BLOCK][SBLIMIT])
{
int sb, j, ch, gr, qnt_coeff_index, sig;
int nch = glopts->num_channels_out;
int sblimit = glopts->sblimit;
int jsbound = glopts->jsbound;
FLOAT d;
for (gr = 0; gr < 3; gr++)
for (j = 0; j < SCALE_BLOCK; j++)
for (sb = 0; sb < sblimit; sb++)
for (ch = 0; ch < ((sb < jsbound) ? nch : 1); ch++)
if (bit_alloc[ch][sb]) {
/* scale and quantize FLOATing point sample */
if (nch == 2 && sb >= jsbound) /* use j-stereo samples */
d = j_samps[gr][j][sb] / scalefactor[j_scale[gr][sb]];
else
d = sb_samples[ch][gr][j][sb] / scalefactor[sf_index[ch][gr][sb]];
/* Check that the wrong scale factor hasn't been chosen - which would
result in a scaled sample being > 1.0 This error shouldn't ever happen
*unless* something went wrong in scalefactor calc
if (mod (d) > 1.0) fprintf (stderr, "Not scaled properly %d %d %d %d\n",
ch, gr, j, sb); */
{
/* 'index' indicates which "step line" we are using */
int index = line[glopts->tablenum][sb];
/* Find the "step index" within that line */
qnt_coeff_index = step_index[index][bit_alloc[ch][sb]];
}
d = d * a[qnt_coeff_index] + b[qnt_coeff_index];
/* extract MSB N-1 bits from the FLOATing point sample */
if (d >= 0)
sig = 1;
else {
sig = 0;
d += 1.0;
}
sbband[ch][gr][j][sb] =
(unsigned int) (d * (FLOAT) steps2n[qnt_coeff_index]);
/* tag the inverted sign bit to sbband at position N */
/* The bit inversion is a must for grouping with 3,5,9 steps so it is done
for all subbands */
if (sig)
sbband[ch][gr][j][sb] |= steps2n[qnt_coeff_index];
}
/* Set everything above the sblimit to 0 */
for (ch = 0; ch < nch; ch++)
for (gr = 0; gr < 3; gr++)
for (sb = 0; sb < SCALE_BLOCK; sb++)
for (j = sblimit; j < SBLIMIT; j++)
sbband[ch][gr][sb][j] = 0;
}
/************************************************************************
sample_encoding
PURPOSE:Put one frame of subband samples on to the bitstream
SEMANTICS: The number of bits allocated per sample is read from
the bit allocation information #bit_alloc#. Layer 2
supports writing grouped samples for quantization steps
that are not a power of 2.
***********************************************************************/
void write_samples(twolame_options * glopts,
unsigned int sbband[2][3][SCALE_BLOCK][SBLIMIT],
unsigned int bit_alloc[2][SBLIMIT], bit_stream * bs)
{
unsigned int nch = glopts->num_channels_out;
unsigned int sblimit = glopts->sblimit;
unsigned int jsbound = glopts->jsbound;
unsigned int sb, j, ch, gr, x, y;
unsigned int temp;
for (gr = 0; gr < 3; gr++)
for (j = 0; j < SCALE_BLOCK; j += 3)
for (sb = 0; sb < sblimit; sb++)
for (ch = 0; ch < ((sb < jsbound) ? nch : 1); ch++) {
if (bit_alloc[ch][sb]) {
int thisline = line[glopts->tablenum][sb];
int thisstep_index = step_index[thisline][bit_alloc[ch][sb]];
/* Check how many samples per codeword */
if (group[thisstep_index] == 3) {
/* Going to send 1 sample per codeword -> 3 samples */
for (x = 0; x < 3; x++) {
buffer_putbits(bs, sbband[ch][gr][j + x][sb], bits[thisstep_index]);
}
} else {
/* ISO11172 Sec C.1.5.2.8 If steps=3, 5 or 9, then three consecutive
samples are coded as one codeword i.e. only one value (V) is
transmitted for this triplet. If the 3 subband samples are x,y,z
then V = (steps*steps)*z + steps*y +x */
y = steps[thisstep_index];
temp =
sbband[ch][gr][j][sb] + sbband[ch][gr][j + 1][sb] * y +
sbband[ch][gr][j + 2][sb] * y * y;
buffer_putbits(bs, temp, bits[thisstep_index]);
}
}
}
}
/************************************************************************
*
* bits_for_nonoise (Layer II)
*
* PURPOSE:Returns the number of bits required to produce a
* mask-to-noise ratio better or equal to the noise/no_noise threshold.
*
* SEMANTICS:
* bbal = # bits needed for encoding bit allocation
* bsel = # bits needed for encoding scalefactor select information
* banc = # bits needed for ancillary data (header info included)
*
* For each subband and channel, will add bits until one of the
* following occurs:
* - Hit maximum number of bits we can allocate for that subband
* - MNR is better than or equal to the minimum masking level
* (NOISY_MIN_MNR)
* Then the bits required for scalefactors, scfsi, bit allocation,
* and the subband samples are tallied (#req_bits#) and returned.
*
* (NOISY_MIN_MNR) is the smallest MNR a subband can have before it is
* counted as 'noisy' by the logic which chooses the number of JS
* subbands.
*
* Joint stereo is supported.
*
************************************************************************/
int bits_for_nonoise(twolame_options * glopts,
FLOAT SMR[2][SBLIMIT],
unsigned int scfsi[2][SBLIMIT], FLOAT min_mnr,
unsigned int bit_alloc[2][SBLIMIT])
{
frame_header *header = &glopts->header;
int sb, ch, ba;
int nch = glopts->num_channels_out;
int sblimit = glopts->sblimit;
int jsbound = glopts->jsbound;
int req_bits = 0, bbal = 0, berr = 0, banc = 32;
int maxAlloc, sel_bits, sc_bits, smp_bits;
static const int sfsPerScfsi[] = { 3, 2, 1, 2 }; /* lookup # sfs per scfsi */
/* MFC Feb 2003 This works out the basic number of bits just to get a valid (but empty) frame.
This needs to be done for every frame, since a joint_stereo frame will change the number of
basic bits (depending on the sblimit in the particular js mode that's been selected */
/* Make sure there's room for the error protection bits */
if (header->error_protection)
berr = 16;
else
berr = 0;
/* Count the number of bits required to encode the quantization index for both channels in each
subband. If we're above the jsbound, then pretend we only have one channel */
for (sb = 0; sb < jsbound; ++sb)
bbal += nch * nbal[line[glopts->tablenum][sb]]; // (*alloc)[sb][0].bits;
for (sb = jsbound; sb < sblimit; ++sb)
bbal += nbal[line[glopts->tablenum][sb]]; // (*alloc)[sb][0].bits;
req_bits = banc + bbal + berr;
for (sb = 0; sb < sblimit; ++sb)
for (ch = 0; ch < ((sb < jsbound) ? nch : 1); ++ch) {
int thisline = line[glopts->tablenum][sb];
/* How many possible steps are there to choose from ? */
maxAlloc = (1 << nbal[line[glopts->tablenum][sb]]) - 1; // (*alloc)[sb][0].bits) - 1;
sel_bits = sc_bits = smp_bits = 0;
/* Keep choosing the next number of steps (and hence our SNR value) until we have the
required MNR value */
for (ba = 0; ba < maxAlloc - 1; ++ba) {
int thisstep_index = step_index[thisline][ba];
if ((SNR[thisstep_index] - SMR[ch][sb]) >= min_mnr)
break; /* we found enough bits */
}
if (nch == 2 && sb >= jsbound) /* check other JS channel */
for (; ba < maxAlloc - 1; ++ba) {
int thisstep_index = step_index[thisline][ba];
if ((SNR[thisstep_index] - SMR[1 - ch][sb]) >= min_mnr)
break;
}
if (ba > 0) {
// smp_bits = SCALE_BLOCK * ((*alloc)[sb][ba].group * (*alloc)[sb][ba].bits);
int thisstep_index = step_index[thisline][ba];
smp_bits = SCALE_BLOCK * group[thisstep_index] * bits[thisstep_index];
/* scale factor bits required for subband */
sel_bits = 2;
sc_bits = 6 * sfsPerScfsi[scfsi[ch][sb]];
if (nch == 2 && sb >= jsbound) {
/* each new js sb has L+R scfsis */
sel_bits += 2;
sc_bits += 6 * sfsPerScfsi[scfsi[1 - ch][sb]];
}
req_bits += smp_bits + sel_bits + sc_bits;
}
bit_alloc[ch][sb] = ba;
}
return req_bits;
}
/* must be called before calling main_bit_allocation */
int init_bit_allocation(twolame_options * glopts)
{
frame_header *header = &glopts->header;
int nch = glopts->num_channels_out;
int brindex;
/* these are the tables which specify the limits within which the VBR can vary You can't vary
outside these ranges, otherwise a new alloc table would have to be loaded in the middle of
encoding. This VBR hack is dodgy - the standard says that LayerII decoders don't have to
support a variable bitrate, but Layer3 decoders must do so. Hence, it is unlikely that a
compliant layer2 decoder would be written to dynmically change allocation tables. *BUT* a
layer3 encoder might handle it by default, meaning we could switch tables mid-encode and
enjoy a wider range of bitrates for the VBR encoding. None of this needs to be done for LSF,
since there is only *one* possible alloc table in LSF MFC Feb 2003 */
static const int vbrlimits[2][3][2] = {
/* MONO */
{ /* 44 */ {6, 10},
/* 48 */ {3, 10},
/* 32 */ {6, 10}},
/* STEREO */
{ /* 44 */ {10, 14},
/* 48 */ {7, 14},
/* 32 */ {10, 14}}
};
for (brindex = 0; brindex < 15; brindex++)
glopts->bitrateindextobits[brindex] = 0;
if (header->version == 0) {
/* LSF: so can use any bitrate index from 1->15 */
glopts->lower_index = 1;
glopts->upper_index = 14;
} else {
int sfreq = header->samplerate_idx;
glopts->lower_index = vbrlimits[nch - 1][sfreq][0];
glopts->upper_index = vbrlimits[nch - 1][sfreq][1];
}
if (glopts->vbr_upper_index > 0) {
/* User is requesting a specific upperbitrate */
if ((glopts->vbr_upper_index < glopts->lower_index) ||
(glopts->vbr_upper_index > glopts->upper_index)) {
fprintf(stderr, "Can't satisfy upper bitrate index constraint. out of bounds. %i\n",
glopts->vbr_upper_index);
return -2;
} else
glopts->upper_index = glopts->vbr_upper_index;
}
/* set up a conversion table for bitrateindex->bits for this version/sampl freq This will be
used to find the best bitrate to cope with the number of bits that are needed (as determined
by vbr_bits_for_nonoise) */
for (brindex = glopts->lower_index; brindex <= glopts->upper_index; brindex++) {
glopts->bitrateindextobits[brindex] =
(int) (1152.0 / (glopts->samplerate_out / 1000.0) * (FLOAT) glopts->bitrate);
}
return 0;
}
/************************************************************************
*
* main_bit_allocation (Layer II)
*
* PURPOSE:For joint stereo mode, determines which of the 4 joint
* stereo modes is needed. Then calls *_a_bit_allocation(), which
* allocates bits for each of the subbands until there are no more bits
* left, or the MNR is at the noise/no_noise threshold.
*
* SEMANTICS:
*
* For joint stereo mode, joint stereo is changed to stereo if
* there are enough bits to encode stereo at or better than the
* no-noise threshold (NOISY_MIN_MNR). Otherwise, the system
* iteratively allocates less bits by using joint stereo until one
* of the following occurs:
* - there are no more noisy subbands (MNR >= NOISY_MIN_MNR)
* - mode_ext has been reduced to 0, which means that all but the
* lowest 4 subbands have been converted from stereo to joint
* stereo, and no more subbands may be converted
*
* This function calls *_bits_for_nonoise() and *_a_bit_allocation().
*
************************************************************************/
void main_bit_allocation(twolame_options * glopts,
FLOAT SMR[2][SBLIMIT],
unsigned int scfsi[2][SBLIMIT],
unsigned int bit_alloc[2][SBLIMIT], int *adb)
{
frame_header *header = &glopts->header;
int noisy_sbs;
int mode = glopts->mode;
int mode_ext, lay;
int rq_db; /* av_db = *adb; Not Used MFC Nov 99 */
int guessindex = 0;
if (mode == TWOLAME_JOINT_STEREO) {
header->mode = TWOLAME_STEREO;
header->mode_ext = 0;
glopts->jsbound = glopts->sblimit;
if ((rq_db = bits_for_nonoise(glopts, SMR, scfsi, 0, bit_alloc)) > *adb) {
header->mode = TWOLAME_JOINT_STEREO;
mode_ext = 4; /* 3 is least severe reduction */
lay = header->lay;
do {
--mode_ext;
glopts->jsbound = get_js_bound(mode_ext);
rq_db = bits_for_nonoise(glopts, SMR, scfsi, 0, bit_alloc);
}
while ((rq_db > *adb) && (mode_ext > 0));
header->mode_ext = mode_ext;
} /* well we either eliminated noisy sbs or mode_ext == 0 */
}
/* decide on which bit allocation method to use */
if (glopts->vbr == FALSE) {
/* Just do the old bit allocation method */
noisy_sbs = a_bit_allocation(glopts, SMR, scfsi, bit_alloc, adb);
} else {
/* do the VBR bit allocation method */
header->bitrate_index = glopts->lower_index;
*adb = available_bits(glopts);
{
int brindex;
int found = FALSE;
/* Work out how many bits are needed for there to be no noise (ie all MNR > VBRLEVEL) */
int req = bits_for_nonoise(glopts, SMR, scfsi, glopts->vbrlevel, bit_alloc);
/* Look up this value in the bitrateindextobits table to find what bitrate we should
use for this frame */
for (brindex = glopts->lower_index; brindex <= glopts->upper_index; brindex++) {
if (glopts->bitrateindextobits[brindex] > req) {
/* this method always *overestimates* the bits that are needed i.e. it will
usually guess right but when it's wrong it'll guess a higher bitrate than
actually required. e.g. on "messages from earth" track 6, the guess was
wrong on 75/36341 frames. each time it guessed higher. MFC Feb 2003 */
guessindex = brindex;
found = TRUE;
break;
}
}
/* Just for sanity */
if (found == FALSE)
guessindex = glopts->upper_index;
}
header->bitrate_index = guessindex;
*adb = available_bits(glopts);
/* update the statistics */
glopts->vbrstats[header->bitrate_index]++;
if (glopts->verbosity > 3) {
/* print out the VBR stats every 1000th frame */
int i;
if ((glopts->vbr_frame_count++ % 1000) == 0) {
for (i = 1; i < 15; i++)
fprintf(stderr, "%4i ", glopts->vbrstats[i]);
fprintf(stderr, "\n");
}
/* Print out *every* frames bitrateindex, bits required, and bits available at this
bitrate */
if (glopts->verbosity > 5)
fprintf(stderr,
"> bitrate index %2i has %i bits available to encode the %i bits\n",
header->bitrate_index, *adb,
bits_for_nonoise(glopts, SMR, scfsi, glopts->vbrlevel, bit_alloc));
}
noisy_sbs = vbr_bit_allocation(glopts, SMR, scfsi, bit_alloc, adb);
}
}
static void vbr_maxmnr(FLOAT mnr[2][SBLIMIT], char used[2][SBLIMIT], int sblimit,
int nch, int *min_sb, int *min_ch, FLOAT vbrlevel)
{
int sb, ch;
FLOAT small;
small = 999999.0;
*min_sb = -1;
*min_ch = -1;
#define NEWBITx
#ifdef NEWBIT
/* Keep going until all subbands have reached the MNR level that we specified */
for (ch = 0; ch < nch; ch++)
for (sb = 0; sb < sblimit; sb++)
if (mnr[ch][sb] < vbrlevel) {
*min_sb = sb;
*min_ch = ch;
// fprintf(stderr,".");
// fflush(stderr);
return;
}
#endif
/* Then start adding bits to whichever is the min MNR */
for (ch = 0; ch < nch; ++ch)
for (sb = 0; sb < sblimit; sb++)
if (used[ch][sb] != 2 && small > mnr[ch][sb]) {
small = mnr[ch][sb];
*min_sb = sb;
*min_ch = ch;
}
// fprintf(stderr,"Min sb: %i\n",*min_sb);
}
/********************
MFC Feb 2003
vbr_bit_allocation is different to the normal a_bit_allocation in that
it is known beforehand that there are definitely enough bits to do what we
have to - i.e. a bitrate was specificially chosen in main_bit_allocation so
that we have enough bits to encode what we have to.
This function should take that into account and just greedily assign
the bits, rather than fussing over the minimum MNR subband - we know
each subband gets its required bits, why quibble?
This function doesn't chew much CPU, so I haven't made any attempt
to do this yet.
*********************/
int vbr_bit_allocation(twolame_options * glopts,
FLOAT SMR[2][SBLIMIT],
unsigned int scfsi[2][SBLIMIT], unsigned int bit_alloc[2][SBLIMIT], int *adb)
{
int sb, min_ch, min_sb, oth_ch, ch, increment, scale, seli, ba;
int bspl, bscf, bsel, ad, bbal = 0;
frame_header *header = &glopts->header;
FLOAT mnr[2][SBLIMIT];
char used[2][SBLIMIT];
int nch = glopts->num_channels_out;
int sblimit = glopts->sblimit;
int jsbound = glopts->jsbound;
int banc, berr;
static const int sfsPerScfsi[] = { 3, 2, 1, 2 }; /* lookup # sfs per scfsi */
int thisstep_index;
if (header->error_protection) {
berr = 16; /* added 92-08-11 shn */
banc = 32;
} else {
berr = 0;
banc = 32;
}
/* No need to worry about jsbound here as JS is disabled for VBR mode */
for (sb = 0; sb < sblimit; sb++)
bbal += nch * nbal[line[glopts->tablenum][sb]];
*adb -= bbal + berr + banc;
ad = *adb;
for (sb = 0; sb < sblimit; sb++)
for (ch = 0; ch < nch; ch++) {
mnr[ch][sb] = SNR[0] - SMR[ch][sb];
bit_alloc[ch][sb] = 0;
used[ch][sb] = 0;
}
bspl = bscf = bsel = 0;
do {
/* locate the subband with minimum SMR */
vbr_maxmnr(mnr, used, sblimit, nch, &min_sb, &min_ch, glopts->vbrlevel);
if (min_sb > -1) { /* there was something to find */
int thisline = line[glopts->tablenum][min_sb]; {
/* find increase in bit allocation in subband [min] */
int nextstep_index = step_index[thisline][bit_alloc[min_ch][min_sb] + 1];
increment = SCALE_BLOCK * group[nextstep_index] * bits[nextstep_index];
}
if (used[min_ch][min_sb]) {
/* If we've already increased the limit on this ch/sb, then subtract the last thing
that we added */
thisstep_index = step_index[thisline][bit_alloc[min_ch][min_sb]];
increment -= SCALE_BLOCK * group[thisstep_index] * bits[thisstep_index];
}
/* scale factor bits required for subband [min] */
oth_ch = 1 - min_ch; /* above js bound, need both chans */
if (used[min_ch][min_sb]) {
scale = seli = 0;
} else { /* this channel had no bits or scfs before */
seli = 2;
scale = 6 * sfsPerScfsi[scfsi[min_ch][min_sb]];
if (nch == 2 && min_sb >= jsbound) {
/* each new js sb has L+R scfsis */
seli += 2;
scale += 6 * sfsPerScfsi[scfsi[oth_ch][min_sb]];
}
}
/* check to see enough bits were available for */
/* increasing resolution in the minimum band */
if (ad >= bspl + bscf + bsel + seli + scale + increment) {
/* Then there are enough bits to have another go at allocating */
ba = ++bit_alloc[min_ch][min_sb]; /* next up alloc */
bspl += increment; /* bits for subband sample */
bscf += scale; /* bits for scale factor */
bsel += seli; /* bits for scfsi code */
used[min_ch][min_sb] = 1; /* subband has bits */
thisstep_index = step_index[thisline][ba];
mnr[min_ch][min_sb] = SNR[thisstep_index] - SMR[min_ch][min_sb];
/* Check if this min_sb subband has been fully allocated max bits */
if (ba >= (1 << nbal[line[glopts->tablenum][min_sb]]) - 1) // (*alloc)[min_sb][0].bits)
//
// - 1)
used[min_ch][min_sb] = 2; /* don't let this sb get any more bits */
} else {
used[min_ch][min_sb] = 2; /* can't increase this alloc */
}
}
}
while (min_sb > -1); /* until could find no channel */
/* Calculate the number of bits left */
ad -= bspl + bscf + bsel;
*adb = ad;
for (ch = 0; ch < nch; ch++)
for (sb = sblimit; sb < SBLIMIT; sb++)
bit_alloc[ch][sb] = 0;
return 0;
}
static void maxmnr(FLOAT mnr[2][SBLIMIT], char used[2][SBLIMIT], int sblimit,
int nch, int *min_sb, int *min_ch)
{
int sb, ch;
FLOAT small;
small = 999999.0;
*min_sb = -1;
*min_ch = -1;
for (ch = 0; ch < nch; ++ch)
for (sb = 0; sb < sblimit; sb++)
if (used[ch][sb] != 2 && small > mnr[ch][sb]) {
small = mnr[ch][sb];
*min_sb = sb;
*min_ch = ch;
}
}
/************************************************************************
*
* a_bit_allocation (Layer II)
*
* PURPOSE:Adds bits to the subbands with the lowest mask-to-noise
* ratios, until the maximum number of bits for the subband has
* been allocated.
*
* SEMANTICS:
* 1. Find the subband and channel with the smallest MNR (#min_sb#,
* and #min_ch#)
* 2. Calculate the increase in bits needed if we increase the bit
* allocation to the next higher level
* 3. If there are enough bits available for increasing the resolution
* in #min_sb#, #min_ch#, and the subband has not yet reached its
* maximum allocation, update the bit allocation, MNR, and bits
* available accordingly
* 4. Repeat until there are no more bits left, or no more available
* subbands. (A subband is still available until the maximum
* number of bits for the subband has been allocated, or there
* aren't enough bits to go to the next higher resolution in the
* subband.)
*
************************************************************************/
int a_bit_allocation(twolame_options * glopts, FLOAT SMR[2][SBLIMIT],
unsigned int scfsi[2][SBLIMIT], unsigned int bit_alloc[2][SBLIMIT], int *adb)
{
int sb, min_ch, min_sb, oth_ch, ch, increment, scale, seli, ba;
int bspl, bscf, bsel, ad, bbal = 0;
FLOAT mnr[2][SBLIMIT];
char used[2][SBLIMIT];
frame_header *header = &glopts->header;
int nch = glopts->num_channels_out;
int sblimit = glopts->sblimit;
int jsbound = glopts->jsbound;
int banc, berr;
static const int sfsPerScfsi[] = { 3, 2, 1, 2 }; /* lookup # sfs per scfsi */
int thisstep_index;
if (header->error_protection) {
berr = 16; /* added 92-08-11 shn */
banc = 32;
} else {
berr = 0;
banc = 32;
}
for (sb = 0; sb < jsbound; sb++)
bbal += nch * nbal[line[glopts->tablenum][sb]]; // (*alloc)[sb][0].bits;
for (sb = jsbound; sb < sblimit; sb++)
bbal += nbal[line[glopts->tablenum][sb]]; // (*alloc)[sb][0].bits;
*adb -= bbal + berr + banc;
ad = *adb;
for (sb = 0; sb < sblimit; sb++) {
for (ch = 0; ch < nch; ch++) {
mnr[ch][sb] = SNR[0] - SMR[ch][sb];
bit_alloc[ch][sb] = 0;
used[ch][sb] = 0;
}
}
bspl = bscf = bsel = 0;
do {
/* locate the subband with minimum SMR */
maxmnr(mnr, used, sblimit, nch, &min_sb, &min_ch);
if (min_sb > -1) { /* there was something to find */
int thisline = line[glopts->tablenum][min_sb]; {
/* find increase in bit allocation in subband [min] */
int nextstep_index = step_index[thisline][bit_alloc[min_ch][min_sb] + 1];
increment = SCALE_BLOCK * group[nextstep_index] * bits[nextstep_index];
}
if (used[min_ch][min_sb]) {
/* If we've already increased the limit on this ch/sb, then subtract the last thing
that we added */
thisstep_index = step_index[thisline][bit_alloc[min_ch][min_sb]];
increment -= SCALE_BLOCK * group[thisstep_index] * bits[thisstep_index];
}
/* scale factor bits required for subband [min] */
oth_ch = 1 - min_ch; /* above js bound, need both chans */
if (used[min_ch][min_sb]) {
scale = seli = 0;
} else { /* this channel had no bits or scfs before */
seli = 2;
scale = 6 * sfsPerScfsi[scfsi[min_ch][min_sb]];
if (nch == 2 && min_sb >= jsbound) {
/* each new js sb has L+R scfsis */
seli += 2;
scale += 6 * sfsPerScfsi[scfsi[oth_ch][min_sb]];
}
}
/* check to see enough bits were available for */
/* increasing resolution in the minimum band */
if (ad >= bspl + bscf + bsel + seli + scale + increment) {
/* Then there are enough bits to have another go at allocating */
ba = ++bit_alloc[min_ch][min_sb]; /* next up alloc */
bspl += increment; /* bits for subband sample */
bscf += scale; /* bits for scale factor */
bsel += seli; /* bits for scfsi code */
used[min_ch][min_sb] = 1; /* subband has bits */
thisstep_index = step_index[thisline][ba];
mnr[min_ch][min_sb] = SNR[thisstep_index] - SMR[min_ch][min_sb];
/* Check if this min_sb subband has been fully allocated max bits */
if (ba >= (1 << nbal[line[glopts->tablenum][min_sb]]) - 1) // (*alloc)[min_sb][0].bits)
//
// - 1)
used[min_ch][min_sb] = 2; /* don't let this sb get any more bits */
} else {
used[min_ch][min_sb] = 2; /* can't increase this alloc */
}
if (min_sb >= jsbound && nch == 2) {
/* above jsbound, alloc applies L+R */
ba = bit_alloc[oth_ch][min_sb] = bit_alloc[min_ch][min_sb];
used[oth_ch][min_sb] = used[min_ch][min_sb];
thisstep_index = step_index[thisline][ba];
mnr[oth_ch][min_sb] = SNR[thisstep_index] - SMR[oth_ch][min_sb];
// mnr[oth_ch][min_sb] = SNR[(*alloc)[min_sb][ba].quant + 1] - SMR[oth_ch][min_sb];
}
}
}
while (min_sb > -1); /* until could find no channel */
/* Calculate the number of bits left */
ad -= bspl + bscf + bsel;
*adb = ad;
for (ch = 0; ch < nch; ch++)
for (sb = sblimit; sb < SBLIMIT; sb++)
bit_alloc[ch][sb] = 0;
return 0;
}
// vim:ts=4:sw=4:nowrap:
|