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avformat/mpeg: demux ivtv captions
[ffmpeg.git] / libavcodec / vlc.c
blobf46ecbb55e9542d54cf8e32ece788695653f3125
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 }