FFmpeg  4.3
flac_parser.c
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1 /*
2  * FLAC parser
3  * Copyright (c) 2010 Michael Chinen
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  * FLAC parser
25  *
26  * The FLAC parser buffers input until FLAC_MIN_HEADERS has been found.
27  * Each time it finds and verifies a CRC-8 header it sees which of the
28  * FLAC_MAX_SEQUENTIAL_HEADERS that came before it have a valid CRC-16 footer
29  * that ends at the newly found header.
30  * Headers are scored by FLAC_HEADER_BASE_SCORE plus the max of its crc-verified
31  * children, penalized by changes in sample rate, frame number, etc.
32  * The parser returns the frame with the highest score.
33  **/
34 
35 #include "libavutil/attributes.h"
36 #include "libavutil/crc.h"
37 #include "libavutil/fifo.h"
38 #include "bytestream.h"
39 #include "parser.h"
40 #include "flac.h"
41 
42 /** maximum number of adjacent headers that compare CRCs against each other */
43 #define FLAC_MAX_SEQUENTIAL_HEADERS 4
44 /** minimum number of headers buffered and checked before returning frames */
45 #define FLAC_MIN_HEADERS 10
46 /** estimate for average size of a FLAC frame */
47 #define FLAC_AVG_FRAME_SIZE 8192
48 
49 /** scoring settings for score_header */
50 #define FLAC_HEADER_BASE_SCORE 10
51 #define FLAC_HEADER_CHANGED_PENALTY 7
52 #define FLAC_HEADER_CRC_FAIL_PENALTY 50
53 #define FLAC_HEADER_NOT_PENALIZED_YET 100000
54 #define FLAC_HEADER_NOT_SCORED_YET -100000
55 
56 /** largest possible size of flac header */
57 #define MAX_FRAME_HEADER_SIZE 16
58 
59 typedef struct FLACHeaderMarker {
60  int offset; /**< byte offset from start of FLACParseContext->buffer */
61  int link_penalty[FLAC_MAX_SEQUENTIAL_HEADERS]; /**< array of local scores
62  between this header and the one at a distance equal
63  array position */
64  int max_score; /**< maximum score found after checking each child that
65  has a valid CRC */
66  FLACFrameInfo fi; /**< decoded frame header info */
67  struct FLACHeaderMarker *next; /**< next CRC-8 verified header that
68  immediately follows this one in
69  the bytestream */
70  struct FLACHeaderMarker *best_child; /**< following frame header with
71  which this frame has the best
72  score with */
74 
75 typedef struct FLACParseContext {
76  AVCodecParserContext *pc; /**< parent context */
77  AVCodecContext *avctx; /**< codec context pointer for logging */
78  FLACHeaderMarker *headers; /**< linked-list that starts at the first
79  CRC-8 verified header within buffer */
80  FLACHeaderMarker *best_header; /**< highest scoring header within buffer */
81  int nb_headers_found; /**< number of headers found in the last
82  flac_parse() call */
83  int nb_headers_buffered; /**< number of headers that are buffered */
84  int best_header_valid; /**< flag set when the parser returns junk;
85  if set return best_header next time */
86  AVFifoBuffer *fifo_buf; /**< buffer to store all data until headers
87  can be verified */
88  int end_padded; /**< specifies if fifo_buf's end is padded */
89  uint8_t *wrap_buf; /**< general fifo read buffer when wrapped */
90  int wrap_buf_allocated_size; /**< actual allocated size of the buffer */
91  FLACFrameInfo last_fi; /**< last decoded frame header info */
92  int last_fi_valid; /**< set if last_fi is valid */
94 
95 static int frame_header_is_valid(AVCodecContext *avctx, const uint8_t *buf,
97 {
98  GetBitContext gb;
99  init_get_bits(&gb, buf, MAX_FRAME_HEADER_SIZE * 8);
100  return !ff_flac_decode_frame_header(avctx, &gb, fi, 127);
101 }
102 
103 /**
104  * Non-destructive fast fifo pointer fetching
105  * Returns a pointer from the specified offset.
106  * If possible the pointer points within the fifo buffer.
107  * Otherwise (if it would cause a wrap around,) a pointer to a user-specified
108  * buffer is used.
109  * The pointer can be NULL. In any case it will be reallocated to hold the size.
110  * If the returned pointer will be used after subsequent calls to flac_fifo_read_wrap
111  * then the subsequent calls should pass in a different wrap_buf so as to not
112  * overwrite the contents of the previous wrap_buf.
113  * This function is based on av_fifo_generic_read, which is why there is a comment
114  * about a memory barrier for SMP.
115  */
117  uint8_t **wrap_buf, int *allocated_size)
118 {
119  AVFifoBuffer *f = fpc->fifo_buf;
120  uint8_t *start = f->rptr + offset;
121  uint8_t *tmp_buf;
122 
123  if (start >= f->end)
124  start -= f->end - f->buffer;
125  if (f->end - start >= len)
126  return start;
127 
128  tmp_buf = av_fast_realloc(*wrap_buf, allocated_size, len);
129 
130  if (!tmp_buf) {
131  av_log(fpc->avctx, AV_LOG_ERROR,
132  "couldn't reallocate wrap buffer of size %d", len);
133  return NULL;
134  }
135  *wrap_buf = tmp_buf;
136  do {
137  int seg_len = FFMIN(f->end - start, len);
138  memcpy(tmp_buf, start, seg_len);
139  tmp_buf = (uint8_t*)tmp_buf + seg_len;
140 // memory barrier needed for SMP here in theory
141 
142  start += seg_len - (f->end - f->buffer);
143  len -= seg_len;
144  } while (len > 0);
145 
146  return *wrap_buf;
147 }
148 
149 /**
150  * Return a pointer in the fifo buffer where the offset starts at until
151  * the wrap point or end of request.
152  * len will contain the valid length of the returned buffer.
153  * A second call to flac_fifo_read (with new offset and len) should be called
154  * to get the post-wrap buf if the returned len is less than the requested.
155  **/
157 {
158  AVFifoBuffer *f = fpc->fifo_buf;
159  uint8_t *start = f->rptr + offset;
160 
161  if (start >= f->end)
162  start -= f->end - f->buffer;
163  *len = FFMIN(*len, f->end - start);
164  return start;
165 }
166 
168 {
170  uint8_t *header_buf;
171  int size = 0;
172  header_buf = flac_fifo_read_wrap(fpc, offset,
174  &fpc->wrap_buf,
176  if (frame_header_is_valid(fpc->avctx, header_buf, &fi)) {
177  FLACHeaderMarker **end_handle = &fpc->headers;
178  int i;
179 
180  size = 0;
181  while (*end_handle) {
182  end_handle = &(*end_handle)->next;
183  size++;
184  }
185 
186  *end_handle = av_mallocz(sizeof(**end_handle));
187  if (!*end_handle) {
188  av_log(fpc->avctx, AV_LOG_ERROR,
189  "couldn't allocate FLACHeaderMarker\n");
190  return AVERROR(ENOMEM);
191  }
192  (*end_handle)->fi = fi;
193  (*end_handle)->offset = offset;
194 
195  for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++)
196  (*end_handle)->link_penalty[i] = FLAC_HEADER_NOT_PENALIZED_YET;
197 
198  fpc->nb_headers_found++;
199  size++;
200  }
201  return size;
202 }
203 
205  int buf_size, int search_start)
206 {
207  int size = 0, mod_offset = (buf_size - 1) % 4, i, j;
208  uint32_t x;
209 
210  for (i = 0; i < mod_offset; i++) {
211  if ((AV_RB16(buf + i) & 0xFFFE) == 0xFFF8) {
212  int ret = find_headers_search_validate(fpc, search_start + i);
213  size = FFMAX(size, ret);
214  }
215  }
216 
217  for (; i < buf_size - 1; i += 4) {
218  x = AV_RN32(buf + i);
219  if (((x & ~(x + 0x01010101)) & 0x80808080)) {
220  for (j = 0; j < 4; j++) {
221  if ((AV_RB16(buf + i + j) & 0xFFFE) == 0xFFF8) {
222  int ret = find_headers_search_validate(fpc, search_start + i + j);
223  size = FFMAX(size, ret);
224  }
225  }
226  }
227  }
228  return size;
229 }
230 
231 static int find_new_headers(FLACParseContext *fpc, int search_start)
232 {
234  int search_end, size = 0, read_len, temp;
235  uint8_t *buf;
236  fpc->nb_headers_found = 0;
237 
238  /* Search for a new header of at most 16 bytes. */
239  search_end = av_fifo_size(fpc->fifo_buf) - (MAX_FRAME_HEADER_SIZE - 1);
240  read_len = search_end - search_start + 1;
241  buf = flac_fifo_read(fpc, search_start, &read_len);
242  size = find_headers_search(fpc, buf, read_len, search_start);
243  search_start += read_len - 1;
244 
245  /* If fifo end was hit do the wrap around. */
246  if (search_start != search_end) {
247  uint8_t wrap[2];
248 
249  wrap[0] = buf[read_len - 1];
250  /* search_start + 1 is the post-wrap offset in the fifo. */
251  read_len = search_end - (search_start + 1) + 1;
252 
253  buf = flac_fifo_read(fpc, search_start + 1, &read_len);
254  wrap[1] = buf[0];
255 
256  if ((AV_RB16(wrap) & 0xFFFE) == 0xFFF8) {
257  temp = find_headers_search_validate(fpc, search_start);
258  size = FFMAX(size, temp);
259  }
260  search_start++;
261 
262  /* Continue to do the last half of the wrap. */
263  temp = find_headers_search(fpc, buf, read_len, search_start);
264  size = FFMAX(size, temp);
265  search_start += read_len - 1;
266  }
267 
268  /* Return the size even if no new headers were found. */
269  if (!size && fpc->headers)
270  for (end = fpc->headers; end; end = end->next)
271  size++;
272  return size;
273 }
274 
276  FLACFrameInfo *header_fi,
277  FLACFrameInfo *child_fi,
278  int log_level_offset)
279 {
280  int deduction = 0;
281  if (child_fi->samplerate != header_fi->samplerate) {
282  deduction += FLAC_HEADER_CHANGED_PENALTY;
283  av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
284  "sample rate change detected in adjacent frames\n");
285  }
286  if (child_fi->bps != header_fi->bps) {
287  deduction += FLAC_HEADER_CHANGED_PENALTY;
288  av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
289  "bits per sample change detected in adjacent frames\n");
290  }
291  if (child_fi->is_var_size != header_fi->is_var_size) {
292  /* Changing blocking strategy not allowed per the spec */
293  deduction += FLAC_HEADER_BASE_SCORE;
294  av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
295  "blocking strategy change detected in adjacent frames\n");
296  }
297  if (child_fi->channels != header_fi->channels) {
298  deduction += FLAC_HEADER_CHANGED_PENALTY;
299  av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
300  "number of channels change detected in adjacent frames\n");
301  }
302  return deduction;
303 }
304 
307  FLACHeaderMarker *child,
308  int log_level_offset)
309 {
310  FLACFrameInfo *header_fi = &header->fi, *child_fi = &child->fi;
311  int deduction, deduction_expected = 0, i;
312  deduction = check_header_fi_mismatch(fpc, header_fi, child_fi,
313  log_level_offset);
314  /* Check sample and frame numbers. */
315  if ((child_fi->frame_or_sample_num - header_fi->frame_or_sample_num
316  != header_fi->blocksize) &&
317  (child_fi->frame_or_sample_num
318  != header_fi->frame_or_sample_num + 1)) {
319  FLACHeaderMarker *curr;
320  int64_t expected_frame_num, expected_sample_num;
321  /* If there are frames in the middle we expect this deduction,
322  as they are probably valid and this one follows it */
323 
324  expected_frame_num = expected_sample_num = header_fi->frame_or_sample_num;
325  curr = header;
326  while (curr != child) {
327  /* Ignore frames that failed all crc checks */
328  for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++) {
330  expected_frame_num++;
331  expected_sample_num += curr->fi.blocksize;
332  break;
333  }
334  }
335  curr = curr->next;
336  }
337 
338  if (expected_frame_num == child_fi->frame_or_sample_num ||
339  expected_sample_num == child_fi->frame_or_sample_num)
340  deduction_expected = deduction ? 0 : 1;
341 
342  deduction += FLAC_HEADER_CHANGED_PENALTY;
343  av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
344  "sample/frame number mismatch in adjacent frames\n");
345  }
346 
347  /* If we have suspicious headers, check the CRC between them */
348  if (deduction && !deduction_expected) {
349  FLACHeaderMarker *curr;
350  int read_len;
351  uint8_t *buf;
352  uint32_t crc = 1;
353  int inverted_test = 0;
354 
355  /* Since CRC is expensive only do it if we haven't yet.
356  This assumes a CRC penalty is greater than all other check penalties */
357  curr = header->next;
358  for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS && curr != child; i++)
359  curr = curr->next;
360 
363  FLACHeaderMarker *start, *end;
364 
365  /* Although overlapping chains are scored, the crc should never
366  have to be computed twice for a single byte. */
367  start = header;
368  end = child;
369  if (i > 0 &&
370  header->link_penalty[i - 1] >= FLAC_HEADER_CRC_FAIL_PENALTY) {
371  while (start->next != child)
372  start = start->next;
373  inverted_test = 1;
374  } else if (i > 0 &&
375  header->next->link_penalty[i-1] >=
377  end = header->next;
378  inverted_test = 1;
379  }
380 
381  read_len = end->offset - start->offset;
382  buf = flac_fifo_read(fpc, start->offset, &read_len);
383  crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf, read_len);
384  read_len = (end->offset - start->offset) - read_len;
385 
386  if (read_len) {
387  buf = flac_fifo_read(fpc, end->offset - read_len, &read_len);
388  crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), crc, buf, read_len);
389  }
390  }
391 
392  if (!crc ^ !inverted_test) {
393  deduction += FLAC_HEADER_CRC_FAIL_PENALTY;
394  av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
395  "crc check failed from offset %i (frame %"PRId64") to %i (frame %"PRId64")\n",
396  header->offset, header_fi->frame_or_sample_num,
397  child->offset, child_fi->frame_or_sample_num);
398  }
399  }
400  return deduction;
401 }
402 
403 /**
404  * Score a header.
405  *
406  * Give FLAC_HEADER_BASE_SCORE points to a frame for existing.
407  * If it has children, (subsequent frames of which the preceding CRC footer
408  * validates against this one,) then take the maximum score of the children,
409  * with a penalty of FLAC_HEADER_CHANGED_PENALTY applied for each change to
410  * bps, sample rate, channels, but not decorrelation mode, or blocksize,
411  * because it can change often.
412  **/
414 {
415  FLACHeaderMarker *child;
416  int dist = 0;
417  int child_score;
418  int base_score = FLAC_HEADER_BASE_SCORE;
419  if (header->max_score != FLAC_HEADER_NOT_SCORED_YET)
420  return header->max_score;
421 
422  /* Modify the base score with changes from the last output header */
423  if (fpc->last_fi_valid) {
424  /* Silence the log since this will be repeated if selected */
425  base_score -= check_header_fi_mismatch(fpc, &fpc->last_fi, &header->fi,
426  AV_LOG_DEBUG);
427  }
428 
429  header->max_score = base_score;
430 
431  /* Check and compute the children's scores. */
432  child = header->next;
433  for (dist = 0; dist < FLAC_MAX_SEQUENTIAL_HEADERS && child; dist++) {
434  /* Look at the child's frame header info and penalize suspicious
435  changes between the headers. */
436  if (header->link_penalty[dist] == FLAC_HEADER_NOT_PENALIZED_YET) {
437  header->link_penalty[dist] = check_header_mismatch(fpc, header,
438  child, AV_LOG_DEBUG);
439  }
440  child_score = score_header(fpc, child) - header->link_penalty[dist];
441 
442  if (FLAC_HEADER_BASE_SCORE + child_score > header->max_score) {
443  /* Keep the child because the frame scoring is dynamic. */
444  header->best_child = child;
445  header->max_score = base_score + child_score;
446  }
447  child = child->next;
448  }
449 
450  return header->max_score;
451 }
452 
454 {
455  FLACHeaderMarker *curr;
456  int best_score = 0;//FLAC_HEADER_NOT_SCORED_YET;
457  /* First pass to clear all old scores. */
458  for (curr = fpc->headers; curr; curr = curr->next)
460 
461  /* Do a second pass to score them all. */
462  for (curr = fpc->headers; curr; curr = curr->next) {
463  if (score_header(fpc, curr) > best_score) {
464  fpc->best_header = curr;
465  best_score = curr->max_score;
466  }
467  }
468 }
469 
470 static int get_best_header(FLACParseContext *fpc, const uint8_t **poutbuf,
471  int *poutbuf_size)
472 {
474  FLACHeaderMarker *child = header->best_child;
475  if (!child) {
476  *poutbuf_size = av_fifo_size(fpc->fifo_buf) - header->offset;
477  } else {
478  *poutbuf_size = child->offset - header->offset;
479 
480  /* If the child has suspicious changes, log them */
481  check_header_mismatch(fpc, header, child, 0);
482  }
483 
484  if (header->fi.channels != fpc->avctx->channels ||
485  !fpc->avctx->channel_layout) {
486  fpc->avctx->channels = header->fi.channels;
488  }
489  fpc->avctx->sample_rate = header->fi.samplerate;
490  fpc->pc->duration = header->fi.blocksize;
491  *poutbuf = flac_fifo_read_wrap(fpc, header->offset, *poutbuf_size,
492  &fpc->wrap_buf,
494 
495 
496  if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS) {
497  if (header->fi.is_var_size)
498  fpc->pc->pts = header->fi.frame_or_sample_num;
499  else if (header->best_child)
500  fpc->pc->pts = header->fi.frame_or_sample_num * header->fi.blocksize;
501  }
502 
503  fpc->best_header_valid = 0;
504  fpc->last_fi_valid = 1;
505  fpc->last_fi = header->fi;
506 
507  /* Return the negative overread index so the client can compute pos.
508  This should be the amount overread to the beginning of the child */
509  if (child)
510  return child->offset - av_fifo_size(fpc->fifo_buf);
511  return 0;
512 }
513 
515  const uint8_t **poutbuf, int *poutbuf_size,
516  const uint8_t *buf, int buf_size)
517 {
518  FLACParseContext *fpc = s->priv_data;
519  FLACHeaderMarker *curr;
520  int nb_headers;
521  const uint8_t *read_end = buf;
522  const uint8_t *read_start = buf;
523 
526  if (frame_header_is_valid(avctx, buf, &fi)) {
527  s->duration = fi.blocksize;
528  if (!avctx->sample_rate)
529  avctx->sample_rate = fi.samplerate;
530  if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS) {
531  fpc->pc->pts = fi.frame_or_sample_num;
532  if (!fi.is_var_size)
533  fpc->pc->pts *= fi.blocksize;
534  }
535  }
536  *poutbuf = buf;
537  *poutbuf_size = buf_size;
538  return buf_size;
539  }
540 
541  fpc->avctx = avctx;
542  if (fpc->best_header_valid)
543  return get_best_header(fpc, poutbuf, poutbuf_size);
544 
545  /* If a best_header was found last call remove it with the buffer data. */
546  if (fpc->best_header && fpc->best_header->best_child) {
549 
550  /* Remove headers in list until the end of the best_header. */
551  for (curr = fpc->headers; curr != best_child; curr = temp) {
552  if (curr != fpc->best_header) {
553  av_log(avctx, AV_LOG_DEBUG,
554  "dropping low score %i frame header from offset %i to %i\n",
555  curr->max_score, curr->offset, curr->next->offset);
556  }
557  temp = curr->next;
558  av_free(curr);
559  fpc->nb_headers_buffered--;
560  }
561  /* Release returned data from ring buffer. */
562  av_fifo_drain(fpc->fifo_buf, best_child->offset);
563 
564  /* Fix the offset for the headers remaining to match the new buffer. */
565  for (curr = best_child->next; curr; curr = curr->next)
566  curr->offset -= best_child->offset;
567 
568  best_child->offset = 0;
569  fpc->headers = best_child;
571  fpc->best_header = best_child;
572  return get_best_header(fpc, poutbuf, poutbuf_size);
573  }
574  fpc->best_header = NULL;
575  } else if (fpc->best_header) {
576  /* No end frame no need to delete the buffer; probably eof */
578 
579  for (curr = fpc->headers; curr != fpc->best_header; curr = temp) {
580  temp = curr->next;
581  av_free(curr);
582  fpc->nb_headers_buffered--;
583  }
584  fpc->headers = fpc->best_header->next;
585  av_freep(&fpc->best_header);
586  fpc->nb_headers_buffered--;
587  }
588 
589  /* Find and score new headers. */
590  /* buf_size is zero when flushing, so check for this since we do */
591  /* not want to try to read more input once we have found the end. */
592  /* Also note that buf can't be NULL. */
593  while ((buf_size && read_end < buf + buf_size &&
595  || (!buf_size && !fpc->end_padded)) {
596  int start_offset;
597 
598  /* Pad the end once if EOF, to check the final region for headers. */
599  if (!buf_size) {
600  fpc->end_padded = 1;
601  read_end = read_start + MAX_FRAME_HEADER_SIZE;
602  } else {
603  /* The maximum read size is the upper-bound of what the parser
604  needs to have the required number of frames buffered */
605  int nb_desired = FLAC_MIN_HEADERS - fpc->nb_headers_buffered + 1;
606  read_end = read_end + FFMIN(buf + buf_size - read_end,
607  nb_desired * FLAC_AVG_FRAME_SIZE);
608  }
609 
610  if (!av_fifo_space(fpc->fifo_buf) &&
612  fpc->nb_headers_buffered * 20) {
613  /* There is less than one valid flac header buffered for 20 headers
614  * buffered. Therefore the fifo is most likely filled with invalid
615  * data and the input is not a flac file. */
616  goto handle_error;
617  }
618 
619  /* Fill the buffer. */
620  if ( av_fifo_space(fpc->fifo_buf) < read_end - read_start
621  && av_fifo_realloc2(fpc->fifo_buf, (read_end - read_start) + 2*av_fifo_size(fpc->fifo_buf)) < 0) {
622  av_log(avctx, AV_LOG_ERROR,
623  "couldn't reallocate buffer of size %"PTRDIFF_SPECIFIER"\n",
624  (read_end - read_start) + av_fifo_size(fpc->fifo_buf));
625  goto handle_error;
626  }
627 
628  if (buf_size) {
629  av_fifo_generic_write(fpc->fifo_buf, (void*) read_start,
630  read_end - read_start, NULL);
631  } else {
632  int8_t pad[MAX_FRAME_HEADER_SIZE] = { 0 };
633  av_fifo_generic_write(fpc->fifo_buf, pad, sizeof(pad), NULL);
634  }
635 
636  /* Tag headers and update sequences. */
637  start_offset = av_fifo_size(fpc->fifo_buf) -
638  ((read_end - read_start) + (MAX_FRAME_HEADER_SIZE - 1));
639  start_offset = FFMAX(0, start_offset);
640  nb_headers = find_new_headers(fpc, start_offset);
641 
642  if (nb_headers < 0) {
643  av_log(avctx, AV_LOG_ERROR,
644  "find_new_headers couldn't allocate FLAC header\n");
645  goto handle_error;
646  }
647 
648  fpc->nb_headers_buffered = nb_headers;
649  /* Wait till FLAC_MIN_HEADERS to output a valid frame. */
650  if (!fpc->end_padded && fpc->nb_headers_buffered < FLAC_MIN_HEADERS) {
651  if (read_end < buf + buf_size) {
652  read_start = read_end;
653  continue;
654  } else {
655  goto handle_error;
656  }
657  }
658 
659  /* If headers found, update the scores since we have longer chains. */
660  if (fpc->end_padded || fpc->nb_headers_found)
661  score_sequences(fpc);
662 
663  /* restore the state pre-padding */
664  if (fpc->end_padded) {
665  int warp = fpc->fifo_buf->wptr - fpc->fifo_buf->buffer < MAX_FRAME_HEADER_SIZE;
666  /* HACK: drain the tail of the fifo */
669  if (warp) {
670  fpc->fifo_buf->wptr += fpc->fifo_buf->end -
671  fpc->fifo_buf->buffer;
672  }
673  read_start = read_end = NULL;
674  }
675  }
676 
677  for (curr = fpc->headers; curr; curr = curr->next) {
678  if (!fpc->best_header || curr->max_score > fpc->best_header->max_score) {
679  fpc->best_header = curr;
680  }
681  }
682 
683  if (fpc->best_header && fpc->best_header->max_score <= 0) {
684  // Only accept a bad header if there is no other option to continue
685  if (!buf_size || read_end != buf || fpc->nb_headers_buffered < FLAC_MIN_HEADERS)
686  fpc->best_header = NULL;
687  }
688 
689  if (fpc->best_header) {
690  fpc->best_header_valid = 1;
691  if (fpc->best_header->offset > 0) {
692  /* Output a junk frame. */
693  av_log(avctx, AV_LOG_DEBUG, "Junk frame till offset %i\n",
694  fpc->best_header->offset);
695 
696  /* Set duration to 0. It is unknown or invalid in a junk frame. */
697  s->duration = 0;
698  *poutbuf_size = fpc->best_header->offset;
699  *poutbuf = flac_fifo_read_wrap(fpc, 0, *poutbuf_size,
700  &fpc->wrap_buf,
702  return buf_size ? (read_end - buf) : (fpc->best_header->offset -
703  av_fifo_size(fpc->fifo_buf));
704  }
705  if (!buf_size)
706  return get_best_header(fpc, poutbuf, poutbuf_size);
707  }
708 
709 handle_error:
710  *poutbuf = NULL;
711  *poutbuf_size = 0;
712  return buf_size ? read_end - buf : 0;
713 }
714 
716 {
717  FLACParseContext *fpc = c->priv_data;
718  fpc->pc = c;
719  /* There will generally be FLAC_MIN_HEADERS buffered in the fifo before
720  it drains. This is allocated early to avoid slow reallocation. */
722  if (!fpc->fifo_buf) {
723  av_log(fpc->avctx, AV_LOG_ERROR,
724  "couldn't allocate fifo_buf\n");
725  return AVERROR(ENOMEM);
726  }
727  return 0;
728 }
729 
731 {
732  FLACParseContext *fpc = c->priv_data;
733  FLACHeaderMarker *curr = fpc->headers, *temp;
734 
735  while (curr) {
736  temp = curr->next;
737  av_free(curr);
738  curr = temp;
739  }
740  fpc->headers = NULL;
741  av_fifo_freep(&fpc->fifo_buf);
742  av_freep(&fpc->wrap_buf);
743 }
744 
747  .priv_data_size = sizeof(FLACParseContext),
748  .parser_init = flac_parse_init,
749  .parser_parse = flac_parse,
750  .parser_close = flac_parse_close,
751 };
static int frame_header_is_valid(AVCodecContext *avctx, const uint8_t *buf, FLACFrameInfo *fi)
Definition: flac_parser.c:95
#define NULL
Definition: coverity.c:32
static void score_sequences(FLACParseContext *fpc)
Definition: flac_parser.c:453
int size
if(ret< 0)
Definition: vf_mcdeint.c:279
uint8_t * wptr
Definition: fifo.h:33
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
else temp
Definition: vf_mcdeint.c:256
int64_t frame_or_sample_num
frame number or sample number
Definition: flac.h:88
int codec_ids[5]
Definition: avcodec.h:3521
AVFifoBuffer * fifo_buf
buffer to store all data until headers can be verified
Definition: flac_parser.c:86
int duration
Duration of the current frame.
Definition: avcodec.h:3475
#define FLAC_HEADER_CRC_FAIL_PENALTY
Definition: flac_parser.c:52
FLACCOMMONINFO int blocksize
block size of the frame
Definition: flac.h:86
Macro definitions for various function/variable attributes.
int av_fifo_generic_write(AVFifoBuffer *f, void *src, int size, int(*func)(void *, void *, int))
Feed data from a user-supplied callback to an AVFifoBuffer.
Definition: fifo.c:122
AVCodecContext * avctx
codec context pointer for logging
Definition: flac_parser.c:77
int best_header_valid
flag set when the parser returns junk; if set return best_header next time
Definition: flac_parser.c:84
#define FLAC_AVG_FRAME_SIZE
estimate for average size of a FLAC frame
Definition: flac_parser.c:47
FLACFrameInfo last_fi
last decoded frame header info
Definition: flac_parser.c:91
uint8_t
#define av_cold
Definition: attributes.h:88
int nb_headers_found
number of headers found in the last flac_parse() call
Definition: flac_parser.c:81
#define f(width, name)
Definition: cbs_vp9.c:255
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:90
int wrap_buf_allocated_size
actual allocated size of the buffer
Definition: flac_parser.c:90
int av_fifo_space(const AVFifoBuffer *f)
Return the amount of space in bytes in the AVFifoBuffer, that is the amount of data you can write int...
Definition: fifo.c:82
#define FLAC_HEADER_NOT_SCORED_YET
Definition: flac_parser.c:54
Public header for CRC hash function implementation.
static int get_best_header(FLACParseContext *fpc, const uint8_t **poutbuf, int *poutbuf_size)
Definition: flac_parser.c:470
#define FLAC_HEADER_CHANGED_PENALTY
Definition: flac_parser.c:51
static void flac_parse_close(AVCodecParserContext *c)
Definition: flac_parser.c:730
#define FLAC_MAX_SEQUENTIAL_HEADERS
maximum number of adjacent headers that compare CRCs against each other
Definition: flac_parser.c:43
static const uint8_t header[24]
Definition: sdr2.c:67
static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition: flac_parser.c:514
#define av_log(a,...)
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
#define PTRDIFF_SPECIFIER
Definition: internal.h:261
static int check_header_fi_mismatch(FLACParseContext *fpc, FLACFrameInfo *header_fi, FLACFrameInfo *child_fi, int log_level_offset)
Definition: flac_parser.c:275
FLAC (Free Lossless Audio Codec) decoder/demuxer common functions.
#define AV_RB16
Definition: intreadwrite.h:53
#define AVERROR(e)
Definition: error.h:43
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:197
#define wrap(func)
Definition: neontest.h:65
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:239
#define FFMAX(a, b)
Definition: common.h:94
int ff_flac_decode_frame_header(AVCodecContext *avctx, GetBitContext *gb, FLACFrameInfo *fi, int log_level_offset)
Validate and decode a frame header.
Definition: flac.c:50
uint64_t channel_layout
Audio channel layout.
Definition: avcodec.h:1237
int end_padded
specifies if fifo_buf&#39;s end is padded
Definition: flac_parser.c:88
struct FLACHeaderMarker * next
next CRC-8 verified header that immediately follows this one in the bytestream
Definition: flac_parser.c:67
#define FFMIN(a, b)
Definition: common.h:96
FLACHeaderMarker * headers
linked-list that starts at the first CRC-8 verified header within buffer
Definition: flac_parser.c:78
#define FLAC_MIN_HEADERS
minimum number of headers buffered and checked before returning frames
Definition: flac_parser.c:45
uint8_t * end
Definition: fifo.h:33
uint8_t * rptr
Definition: fifo.h:33
uint32_t av_crc(const AVCRC *ctx, uint32_t crc, const uint8_t *buffer, size_t length)
Calculate the CRC of a block.
Definition: crc.c:392
#define s(width, name)
Definition: cbs_vp9.c:257
void * av_fast_realloc(void *ptr, unsigned int *size, size_t min_size)
Reallocate the given buffer if it is not large enough, otherwise do nothing.
Definition: mem.c:480
static uint8_t * flac_fifo_read_wrap(FLACParseContext *fpc, int offset, int len, uint8_t **wrap_buf, int *allocated_size)
Non-destructive fast fifo pointer fetching Returns a pointer from the specified offset.
Definition: flac_parser.c:116
int last_fi_valid
set if last_fi is valid
Definition: flac_parser.c:92
int max_score
maximum score found after checking each child that has a valid CRC
Definition: flac_parser.c:64
static int find_headers_search_validate(FLACParseContext *fpc, int offset)
Definition: flac_parser.c:167
int av_fifo_size(const AVFifoBuffer *f)
Return the amount of data in bytes in the AVFifoBuffer, that is the amount of data you can read from ...
Definition: fifo.c:77
uint8_t * wrap_buf
general fifo read buffer when wrapped
Definition: flac_parser.c:89
int sample_rate
samples per second
Definition: avcodec.h:1186
int av_fifo_realloc2(AVFifoBuffer *f, unsigned int new_size)
Resize an AVFifoBuffer.
Definition: fifo.c:87
#define FLAC_HEADER_NOT_PENALIZED_YET
Definition: flac_parser.c:53
main external API structure.
Definition: avcodec.h:526
a very simple circular buffer FIFO implementation
static int find_new_headers(FLACParseContext *fpc, int search_start)
Definition: flac_parser.c:231
void ff_flac_set_channel_layout(AVCodecContext *avctx)
Definition: flac.c:196
uint8_t * buffer
Definition: fifo.h:32
static int score_header(FLACParseContext *fpc, FLACHeaderMarker *header)
Score a header.
Definition: flac_parser.c:413
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:659
FLACFrameInfo fi
decoded frame header info
Definition: flac_parser.c:66
#define AV_RN32(p)
Definition: intreadwrite.h:364
int nb_headers_buffered
number of headers that are buffered
Definition: flac_parser.c:83
#define MAX_FRAME_HEADER_SIZE
largest possible size of flac header
Definition: flac_parser.c:57
uint32_t wndx
Definition: fifo.h:34
AVCodecParserContext * pc
parent context
Definition: flac_parser.c:76
FLACHeaderMarker * best_header
highest scoring header within buffer
Definition: flac_parser.c:80
AVFifoBuffer * av_fifo_alloc_array(size_t nmemb, size_t size)
Initialize an AVFifoBuffer.
Definition: fifo.c:49
AVCodecParser ff_flac_parser
Definition: flac_parser.c:745
const AVCRC * av_crc_get_table(AVCRCId crc_id)
Get an initialized standard CRC table.
Definition: crc.c:374
static int find_headers_search(FLACParseContext *fpc, uint8_t *buf, int buf_size, int search_start)
Definition: flac_parser.c:204
static double c[64]
#define PARSER_FLAG_COMPLETE_FRAMES
Definition: avcodec.h:3387
int offset
byte offset from start of FLACParseContext->buffer
Definition: flac_parser.c:60
#define av_free(p)
int len
int channels
number of audio channels
Definition: avcodec.h:1187
static av_cold int flac_parse_init(AVCodecParserContext *c)
Definition: flac_parser.c:715
#define FLAC_HEADER_BASE_SCORE
scoring settings for score_header
Definition: flac_parser.c:50
int is_var_size
specifies if the stream uses variable block sizes or a fixed block size; also determines the meaning ...
Definition: flac.h:89
int link_penalty[FLAC_MAX_SEQUENTIAL_HEADERS]
array of local scores between this header and the one at a distance equal array position ...
Definition: flac_parser.c:61
static uint8_t * flac_fifo_read(FLACParseContext *fpc, int offset, int *len)
Return a pointer in the fifo buffer where the offset starts at until the wrap point or end of request...
Definition: flac_parser.c:156
#define av_freep(p)
void av_fifo_freep(AVFifoBuffer **f)
Free an AVFifoBuffer and reset pointer to NULL.
Definition: fifo.c:63
struct FLACHeaderMarker * best_child
following frame header with which this frame has the best score with
Definition: flac_parser.c:70
void av_fifo_drain(AVFifoBuffer *f, int size)
Discard data from the FIFO.
Definition: fifo.c:233
#define PARSER_FLAG_USE_CODEC_TS
Definition: avcodec.h:3391
static int check_header_mismatch(FLACParseContext *fpc, FLACHeaderMarker *header, FLACHeaderMarker *child, int log_level_offset)
Definition: flac_parser.c:305