vlc.c (22340B)
1 /* 2 * API for creating VLC trees 3 * Copyright (c) 2000, 2001 Fabrice Bellard 4 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> 5 * Copyright (c) 2010 Loren Merritt 6 * 7 * This file is part of FFmpeg. 8 * 9 * FFmpeg is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU Lesser General Public 11 * License as published by the Free Software Foundation; either 12 * version 2.1 of the License, or (at your option) any later version. 13 * 14 * FFmpeg is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 17 * Lesser General Public License for more details. 18 * 19 * You should have received a copy of the GNU Lesser General Public 20 * License along with FFmpeg; if not, write to the Free Software 21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 22 */ 23 24 #include <inttypes.h> 25 #include <stdint.h> 26 #include <stdlib.h> 27 #include <string.h> 28 29 #include "libavutil/attributes.h" 30 #include "libavutil/avassert.h" 31 #include "libavutil/error.h" 32 #include "libavutil/internal.h" 33 #include "libavutil/intreadwrite.h" 34 #include "libavutil/log.h" 35 #include "libavutil/macros.h" 36 #include "libavutil/mem.h" 37 #include "libavutil/qsort.h" 38 #include "libavutil/reverse.h" 39 #include "vlc.h" 40 41 #define GET_DATA(v, table, i, wrap, size) \ 42 { \ 43 const uint8_t *ptr = (const uint8_t *)table + i * wrap; \ 44 switch(size) { \ 45 case 1: \ 46 v = *(const uint8_t *)ptr; \ 47 break; \ 48 case 2: \ 49 v = *(const uint16_t *)ptr; \ 50 break; \ 51 case 4: \ 52 default: \ 53 av_assert1(size == 4); \ 54 v = *(const uint32_t *)ptr; \ 55 break; \ 56 } \ 57 } 58 59 60 static int alloc_table(VLC *vlc, int size, int use_static) 61 { 62 int index = vlc->table_size; 63 64 vlc->table_size += size; 65 if (vlc->table_size > vlc->table_allocated) { 66 if (use_static) 67 abort(); // cannot do anything, vlc_init() is used with too little memory 68 vlc->table_allocated += (1 << vlc->bits); 69 vlc->table = av_realloc_f(vlc->table, vlc->table_allocated, sizeof(*vlc->table)); 70 if (!vlc->table) { 71 vlc->table_allocated = 0; 72 vlc->table_size = 0; 73 return AVERROR(ENOMEM); 74 } 75 memset(vlc->table + vlc->table_allocated - (1 << vlc->bits), 0, sizeof(*vlc->table) << vlc->bits); 76 } 77 return index; 78 } 79 80 #define LOCALBUF_ELEMS 1500 // the maximum currently needed is 1296 by rv34 81 82 static av_always_inline uint32_t bitswap_32(uint32_t x) 83 { 84 return (uint32_t)ff_reverse[ x & 0xFF] << 24 | 85 (uint32_t)ff_reverse[(x >> 8) & 0xFF] << 16 | 86 (uint32_t)ff_reverse[(x >> 16) & 0xFF] << 8 | 87 (uint32_t)ff_reverse[ x >> 24]; 88 } 89 90 typedef struct VLCcode { 91 uint8_t bits; 92 VLCBaseType symbol; 93 /** codeword, with the first bit-to-be-read in the msb 94 * (even if intended for a little-endian bitstream reader) */ 95 uint32_t code; 96 } VLCcode; 97 98 static int vlc_common_init(VLC *vlc, int nb_bits, int nb_codes, 99 VLCcode **buf, int flags) 100 { 101 vlc->bits = nb_bits; 102 vlc->table_size = 0; 103 if (flags & VLC_INIT_USE_STATIC) { 104 av_assert0(nb_codes <= LOCALBUF_ELEMS); 105 } else { 106 vlc->table = NULL; 107 vlc->table_allocated = 0; 108 } 109 if (nb_codes > LOCALBUF_ELEMS) { 110 *buf = av_malloc_array(nb_codes, sizeof(VLCcode)); 111 if (!*buf) 112 return AVERROR(ENOMEM); 113 } 114 115 return 0; 116 } 117 118 static int compare_vlcspec(const void *a, const void *b) 119 { 120 const VLCcode *sa = a, *sb = b; 121 return (sa->code >> 1) - (sb->code >> 1); 122 } 123 124 /** 125 * Build VLC decoding tables suitable for use with get_vlc(). 126 * 127 * @param vlc the context to be initialized 128 * 129 * @param table_nb_bits max length of vlc codes to store directly in this table 130 * (Longer codes are delegated to subtables.) 131 * 132 * @param nb_codes number of elements in codes[] 133 * 134 * @param codes descriptions of the vlc codes 135 * These must be ordered such that codes going into the same subtable are contiguous. 136 * Sorting by VLCcode.code is sufficient, though not necessary. 137 */ 138 static int build_table(VLC *vlc, int table_nb_bits, int nb_codes, 139 VLCcode *codes, int flags) 140 { 141 int table_size, table_index; 142 VLCElem *table; 143 144 if (table_nb_bits > 30) 145 return AVERROR(EINVAL); 146 table_size = 1 << table_nb_bits; 147 table_index = alloc_table(vlc, table_size, flags & VLC_INIT_USE_STATIC); 148 ff_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size); 149 if (table_index < 0) 150 return table_index; 151 table = &vlc->table[table_index]; 152 153 /* first pass: map codes and compute auxiliary table sizes */ 154 for (int i = 0; i < nb_codes; i++) { 155 int n = codes[i].bits; 156 uint32_t code = codes[i].code; 157 int symbol = codes[i].symbol; 158 ff_dlog(NULL, "i=%d n=%d code=0x%"PRIx32"\n", i, n, code); 159 if (n <= table_nb_bits) { 160 /* no need to add another table */ 161 int j = code >> (32 - table_nb_bits); 162 int nb = 1 << (table_nb_bits - n); 163 int inc = 1; 164 165 if (flags & VLC_INIT_OUTPUT_LE) { 166 j = bitswap_32(code); 167 inc = 1 << n; 168 } 169 for (int k = 0; k < nb; k++) { 170 int bits = table[j].len; 171 int oldsym = table[j].sym; 172 ff_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n); 173 if ((bits || oldsym) && (bits != n || oldsym != symbol)) { 174 av_log(NULL, AV_LOG_ERROR, "incorrect codes\n"); 175 return AVERROR_INVALIDDATA; 176 } 177 table[j].len = n; 178 table[j].sym = symbol; 179 j += inc; 180 } 181 } else { 182 /* fill auxiliary table recursively */ 183 uint32_t code_prefix; 184 int index, subtable_bits, j, k; 185 186 n -= table_nb_bits; 187 code_prefix = code >> (32 - table_nb_bits); 188 subtable_bits = n; 189 codes[i].bits = n; 190 codes[i].code = code << table_nb_bits; 191 for (k = i + 1; k < nb_codes; k++) { 192 n = codes[k].bits - table_nb_bits; 193 if (n <= 0) 194 break; 195 code = codes[k].code; 196 if (code >> (32 - table_nb_bits) != code_prefix) 197 break; 198 codes[k].bits = n; 199 codes[k].code = code << table_nb_bits; 200 subtable_bits = FFMAX(subtable_bits, n); 201 } 202 subtable_bits = FFMIN(subtable_bits, table_nb_bits); 203 j = (flags & VLC_INIT_OUTPUT_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix; 204 table[j].len = -subtable_bits; 205 ff_dlog(NULL, "%4x: n=%d (subtable)\n", 206 j, codes[i].bits + table_nb_bits); 207 index = build_table(vlc, subtable_bits, k-i, codes+i, flags); 208 if (index < 0) 209 return index; 210 /* note: realloc has been done, so reload tables */ 211 table = &vlc->table[table_index]; 212 table[j].sym = index; 213 if (table[j].sym != index) { 214 avpriv_request_sample(NULL, "strange codes"); 215 return AVERROR_PATCHWELCOME; 216 } 217 i = k-1; 218 } 219 } 220 221 for (int i = 0; i < table_size; i++) { 222 if (table[i].len == 0) 223 table[i].sym = -1; 224 } 225 226 return table_index; 227 } 228 229 static int vlc_common_end(VLC *vlc, int nb_bits, int nb_codes, VLCcode *codes, 230 int flags, VLCcode localbuf[LOCALBUF_ELEMS]) 231 { 232 int ret = build_table(vlc, nb_bits, nb_codes, codes, flags); 233 234 if (flags & VLC_INIT_USE_STATIC) { 235 if (vlc->table_size != vlc->table_allocated && 236 !(flags & (VLC_INIT_STATIC_OVERLONG & ~VLC_INIT_USE_STATIC))) 237 av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated); 238 av_assert0(ret >= 0); 239 } else { 240 if (codes != localbuf) 241 av_free(codes); 242 if (ret < 0) { 243 av_freep(&vlc->table); 244 return ret; 245 } 246 } 247 return 0; 248 } 249 250 int ff_vlc_init_sparse(VLC *vlc, int nb_bits, int nb_codes, 251 const void *bits, int bits_wrap, int bits_size, 252 const void *codes, int codes_wrap, int codes_size, 253 const void *symbols, int symbols_wrap, int symbols_size, 254 int flags) 255 { 256 VLCcode localbuf[LOCALBUF_ELEMS], *buf = localbuf; 257 int j, ret; 258 259 ret = vlc_common_init(vlc, nb_bits, nb_codes, &buf, flags); 260 if (ret < 0) 261 return ret; 262 263 av_assert0(symbols_size <= 2 || !symbols); 264 j = 0; 265 #define COPY(condition)\ 266 for (int i = 0; i < nb_codes; i++) { \ 267 unsigned len; \ 268 GET_DATA(len, bits, i, bits_wrap, bits_size); \ 269 if (!(condition)) \ 270 continue; \ 271 if (len > 3*nb_bits || len > 32) { \ 272 av_log(NULL, AV_LOG_ERROR, "Too long VLC (%u) in vlc_init\n", len);\ 273 if (buf != localbuf) \ 274 av_free(buf); \ 275 return AVERROR(EINVAL); \ 276 } \ 277 buf[j].bits = len; \ 278 GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size); \ 279 if (buf[j].code >= (1LL<<buf[j].bits)) { \ 280 av_log(NULL, AV_LOG_ERROR, "Invalid code %"PRIx32" for %d in " \ 281 "vlc_init\n", buf[j].code, i); \ 282 if (buf != localbuf) \ 283 av_free(buf); \ 284 return AVERROR(EINVAL); \ 285 } \ 286 if (flags & VLC_INIT_INPUT_LE) \ 287 buf[j].code = bitswap_32(buf[j].code); \ 288 else \ 289 buf[j].code <<= 32 - buf[j].bits; \ 290 if (symbols) \ 291 GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size) \ 292 else \ 293 buf[j].symbol = i; \ 294 j++; \ 295 } 296 COPY(len > nb_bits); 297 // qsort is the slowest part of vlc_init, and could probably be improved or avoided 298 AV_QSORT(buf, j, struct VLCcode, compare_vlcspec); 299 COPY(len && len <= nb_bits); 300 nb_codes = j; 301 302 return vlc_common_end(vlc, nb_bits, nb_codes, buf, 303 flags, localbuf); 304 } 305 306 int ff_vlc_init_from_lengths(VLC *vlc, int nb_bits, int nb_codes, 307 const int8_t *lens, int lens_wrap, 308 const void *symbols, int symbols_wrap, int symbols_size, 309 int offset, int flags, void *logctx) 310 { 311 VLCcode localbuf[LOCALBUF_ELEMS], *buf = localbuf; 312 uint64_t code; 313 int ret, j, len_max = FFMIN(32, 3 * nb_bits); 314 315 ret = vlc_common_init(vlc, nb_bits, nb_codes, &buf, flags); 316 if (ret < 0) 317 return ret; 318 319 j = code = 0; 320 for (int i = 0; i < nb_codes; i++, lens += lens_wrap) { 321 int len = *lens; 322 if (len > 0) { 323 unsigned sym; 324 325 buf[j].bits = len; 326 if (symbols) 327 GET_DATA(sym, symbols, i, symbols_wrap, symbols_size) 328 else 329 sym = i; 330 buf[j].symbol = sym + offset; 331 buf[j++].code = code; 332 } else if (len < 0) { 333 len = -len; 334 } else 335 continue; 336 if (len > len_max || code & ((1U << (32 - len)) - 1)) { 337 av_log(logctx, AV_LOG_ERROR, "Invalid VLC (length %u)\n", len); 338 goto fail; 339 } 340 code += 1U << (32 - len); 341 if (code > UINT32_MAX + 1ULL) { 342 av_log(logctx, AV_LOG_ERROR, "Overdetermined VLC tree\n"); 343 goto fail; 344 } 345 } 346 return vlc_common_end(vlc, nb_bits, j, buf, flags, localbuf); 347 fail: 348 if (buf != localbuf) 349 av_free(buf); 350 return AVERROR_INVALIDDATA; 351 } 352 353 av_cold void ff_vlc_init_table_from_lengths(VLCElem table[], int table_size, 354 int nb_bits, int nb_codes, 355 const int8_t *lens, int lens_wrap, 356 const void *symbols, int symbols_wrap, int symbols_size, 357 int offset, int flags) 358 { 359 VLC vlc = { .table = table, .table_allocated = table_size }; 360 361 ff_vlc_init_from_lengths(&vlc, nb_bits, nb_codes, lens, lens_wrap, 362 symbols, symbols_wrap, symbols_size, 363 offset, flags | VLC_INIT_USE_STATIC, NULL); 364 } 365 366 av_cold const VLCElem *ff_vlc_init_tables_from_lengths(VLCInitState *state, 367 int nb_bits, int nb_codes, 368 const int8_t *lens, int lens_wrap, 369 const void *symbols, int symbols_wrap, int symbols_size, 370 int offset, int flags) 371 { 372 VLC vlc = { .table = state->table, .table_allocated = state->size }; 373 374 ff_vlc_init_from_lengths(&vlc, nb_bits, nb_codes, lens, lens_wrap, 375 symbols, symbols_wrap, symbols_size, 376 offset, flags | VLC_INIT_STATIC_OVERLONG, NULL); 377 378 state->table += vlc.table_size; 379 state->size -= vlc.table_size; 380 381 return vlc.table; 382 } 383 384 av_cold void ff_vlc_init_table_sparse(VLCElem table[], int table_size, 385 int nb_bits, int nb_codes, 386 const void *bits, int bits_wrap, int bits_size, 387 const void *codes, int codes_wrap, int codes_size, 388 const void *symbols, int symbols_wrap, int symbols_size, 389 int flags) 390 { 391 VLC vlc = { .table = table, .table_allocated = table_size }; 392 393 ff_vlc_init_sparse(&vlc, nb_bits, nb_codes, 394 bits, bits_wrap, bits_size, 395 codes, codes_wrap, codes_size, 396 symbols, symbols_wrap, symbols_size, 397 flags | VLC_INIT_USE_STATIC); 398 } 399 400 av_cold const VLCElem *ff_vlc_init_tables_sparse(VLCInitState *state, 401 int nb_bits, int nb_codes, 402 const void *bits, int bits_wrap, int bits_size, 403 const void *codes, int codes_wrap, int codes_size, 404 const void *symbols, int symbols_wrap, int symbols_size, 405 int flags) 406 { 407 VLC vlc = { .table = state->table, .table_allocated = state->size }; 408 409 ff_vlc_init_sparse(&vlc, nb_bits, nb_codes, 410 bits, bits_wrap, bits_size, 411 codes, codes_wrap, codes_size, 412 symbols, symbols_wrap, symbols_size, 413 flags | VLC_INIT_STATIC_OVERLONG); 414 415 state->table += vlc.table_size; 416 state->size -= vlc.table_size; 417 418 return vlc.table; 419 } 420 421 static void add_level(VLC_MULTI_ELEM *table, const int is16bit, 422 const int num, const int numbits, 423 const VLCcode *buf, 424 uint32_t curcode, int curlen, 425 int curlimit, int curlevel, 426 const int minlen, const int max, 427 unsigned* levelcnt, VLC_MULTI_ELEM info) 428 { 429 int max_symbols = VLC_MULTI_MAX_SYMBOLS >> is16bit; 430 for (int i = num-1; i >= max; i--) { 431 for (int j = 0; j < 2; j++) { 432 int newlimit, sym; 433 int t = j ? i-1 : i; 434 int l = buf[t].bits; 435 uint32_t code; 436 437 sym = buf[t].symbol; 438 if (l >= curlimit) 439 return; 440 code = curcode + (buf[t].code >> curlen); 441 newlimit = curlimit - l; 442 l += curlen; 443 if (is16bit) info.val16[curlevel] = sym; 444 else info.val8[curlevel] = sym&0xFF; 445 446 if (curlevel) { // let's not add single entries 447 uint32_t val = code >> (32 - numbits); 448 uint32_t nb = val + (1U << (numbits - l)); 449 info.len = l; 450 info.num = curlevel+1; 451 for (; val < nb; val++) 452 AV_COPY64(table+val, &info); 453 levelcnt[curlevel-1]++; 454 } 455 456 if (curlevel+1 < max_symbols && newlimit >= minlen) { 457 add_level(table, is16bit, num, numbits, buf, 458 code, l, newlimit, curlevel+1, 459 minlen, max, levelcnt, info); 460 } 461 } 462 } 463 } 464 465 static int vlc_multi_gen(VLC_MULTI_ELEM *table, const VLC *single, 466 const int is16bit, const int nb_codes, const int numbits, 467 VLCcode *buf, void *logctx) 468 { 469 int minbits, maxbits, max; 470 unsigned count[VLC_MULTI_MAX_SYMBOLS-1] = { 0, }; 471 VLC_MULTI_ELEM info = { 0 }; 472 int count0 = 0; 473 474 for (int j = 0; j < 1<<numbits; j++) { 475 if (single->table[j].len > 0) { 476 count0 ++; 477 j += (1 << (numbits - single->table[j].len)) - 1; 478 } 479 } 480 481 minbits = 32; 482 maxbits = 0; 483 484 for (int n = nb_codes - count0; n < nb_codes; n++) { 485 minbits = FFMIN(minbits, buf[n].bits); 486 maxbits = FFMAX(maxbits, buf[n].bits); 487 } 488 av_assert0(maxbits <= numbits); 489 490 for (max = nb_codes; max > nb_codes - count0; max--) { 491 // We can only add a code that fits with the shortest other code into the table 492 // We assume the table is sorted by bits and we skip subtables which from our 493 // point of view are basically random corrupted entries 494 // If we have not a single useable vlc we end with max = nb_codes 495 if (buf[max - 1].bits+minbits > numbits) 496 break; 497 } 498 499 for (int j = 0; j < 1<<numbits; j++) { 500 table[j].len = single->table[j].len; 501 table[j].num = single->table[j].len > 0 ? 1 : 0; 502 if (is16bit) 503 table[j].val16[0] = single->table[j].sym; 504 else 505 table[j].val8[0] = single->table[j].sym; 506 } 507 508 add_level(table, is16bit, nb_codes, numbits, buf, 509 0, 0, FFMIN(maxbits, numbits), 0, minbits, max, count, info); 510 511 av_log(logctx, AV_LOG_DEBUG, "Joint: %d/%d/%d/%d/%d codes min=%ubits max=%u\n", 512 count[0], count[1], count[2], count[3], count[4], minbits, max); 513 514 return 0; 515 } 516 517 int ff_vlc_init_multi_from_lengths(VLC *vlc, VLC_MULTI *multi, int nb_bits, int nb_elems, 518 int nb_codes, const int8_t *lens, int lens_wrap, 519 const void *symbols, int symbols_wrap, int symbols_size, 520 int offset, int flags, void *logctx) 521 { 522 VLCcode localbuf[LOCALBUF_ELEMS], *buf = localbuf; 523 uint64_t code; 524 int ret, j, len_max = FFMIN(32, 3 * nb_bits); 525 526 ret = vlc_common_init(vlc, nb_bits, nb_codes, &buf, flags); 527 if (ret < 0) 528 return ret; 529 530 multi->table = av_malloc(sizeof(*multi->table) << nb_bits); 531 if (!multi->table) 532 goto fail; 533 534 j = code = 0; 535 for (int i = 0; i < nb_codes; i++, lens += lens_wrap) { 536 int len = *lens; 537 if (len > 0) { 538 unsigned sym; 539 540 buf[j].bits = len; 541 if (symbols) 542 GET_DATA(sym, symbols, i, symbols_wrap, symbols_size) 543 else 544 sym = i; 545 buf[j].symbol = sym + offset; 546 buf[j++].code = code; 547 } else if (len < 0) { 548 len = -len; 549 } else 550 continue; 551 if (len > len_max || code & ((1U << (32 - len)) - 1)) { 552 av_log(logctx, AV_LOG_ERROR, "Invalid VLC (length %u)\n", len); 553 goto fail; 554 } 555 code += 1U << (32 - len); 556 if (code > UINT32_MAX + 1ULL) { 557 av_log(logctx, AV_LOG_ERROR, "Overdetermined VLC tree\n"); 558 goto fail; 559 } 560 } 561 ret = vlc_common_end(vlc, nb_bits, j, buf, flags, buf); 562 if (ret < 0) 563 goto fail; 564 ret = vlc_multi_gen(multi->table, vlc, nb_elems > 256, j, nb_bits, buf, logctx); 565 if (buf != localbuf) 566 av_free(buf); 567 return ret; 568 fail: 569 if (buf != localbuf) 570 av_free(buf); 571 ff_vlc_free_multi(multi); 572 return AVERROR_INVALIDDATA; 573 } 574 575 void ff_vlc_free_multi(VLC_MULTI *vlc) 576 { 577 av_freep(&vlc->table); 578 } 579 580 void ff_vlc_free(VLC *vlc) 581 { 582 av_freep(&vlc->table); 583 }