FFmpeg  4.3.7
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 #define MAX_FRAME_VERIFY_SIZE (MAX_FRAME_HEADER_SIZE)
59 
60 typedef struct FLACHeaderMarker {
61  int offset; /**< byte offset from start of FLACParseContext->buffer */
62  int link_penalty[FLAC_MAX_SEQUENTIAL_HEADERS]; /**< array of local scores
63  between this header and the one at a distance equal
64  array position */
65  int max_score; /**< maximum score found after checking each child that
66  has a valid CRC */
67  FLACFrameInfo fi; /**< decoded frame header info */
68  struct FLACHeaderMarker *next; /**< next CRC-8 verified header that
69  immediately follows this one in
70  the bytestream */
71  struct FLACHeaderMarker *best_child; /**< following frame header with
72  which this frame has the best
73  score with */
75 
76 typedef struct FLACParseContext {
77  AVCodecParserContext *pc; /**< parent context */
78  AVCodecContext *avctx; /**< codec context pointer for logging */
79  FLACHeaderMarker *headers; /**< linked-list that starts at the first
80  CRC-8 verified header within buffer */
81  FLACHeaderMarker *best_header; /**< highest scoring header within buffer */
82  int nb_headers_found; /**< number of headers found in the last
83  flac_parse() call */
84  int nb_headers_buffered; /**< number of headers that are buffered */
85  int best_header_valid; /**< flag set when the parser returns junk;
86  if set return best_header next time */
87  AVFifoBuffer *fifo_buf; /**< buffer to store all data until headers
88  can be verified */
89  int end_padded; /**< specifies if fifo_buf's end is padded */
90  uint8_t *wrap_buf; /**< general fifo read buffer when wrapped */
91  int wrap_buf_allocated_size; /**< actual allocated size of the buffer */
92  FLACFrameInfo last_fi; /**< last decoded frame header info */
93  int last_fi_valid; /**< set if last_fi is valid */
95 
96 static int frame_header_is_valid(AVCodecContext *avctx, const uint8_t *buf,
98 {
99  GetBitContext gb;
100  init_get_bits(&gb, buf, MAX_FRAME_HEADER_SIZE * 8);
101  return !ff_flac_decode_frame_header(avctx, &gb, fi, 127);
102 }
103 
104 /**
105  * Non-destructive fast fifo pointer fetching
106  * Returns a pointer from the specified offset.
107  * If possible the pointer points within the fifo buffer.
108  * Otherwise (if it would cause a wrap around,) a pointer to a user-specified
109  * buffer is used.
110  * The pointer can be NULL. In any case it will be reallocated to hold the size.
111  * If the returned pointer will be used after subsequent calls to flac_fifo_read_wrap
112  * then the subsequent calls should pass in a different wrap_buf so as to not
113  * overwrite the contents of the previous wrap_buf.
114  * This function is based on av_fifo_generic_read, which is why there is a comment
115  * about a memory barrier for SMP.
116  */
118  uint8_t **wrap_buf, int *allocated_size)
119 {
120  AVFifoBuffer *f = fpc->fifo_buf;
121  uint8_t *start = f->rptr + offset;
122  uint8_t *tmp_buf;
123 
124  if (start >= f->end)
125  start -= f->end - f->buffer;
126  if (f->end - start >= len)
127  return start;
128 
129  tmp_buf = av_fast_realloc(*wrap_buf, allocated_size, len);
130 
131  if (!tmp_buf) {
132  av_log(fpc->avctx, AV_LOG_ERROR,
133  "couldn't reallocate wrap buffer of size %d", len);
134  return NULL;
135  }
136  *wrap_buf = tmp_buf;
137  do {
138  int seg_len = FFMIN(f->end - start, len);
139  memcpy(tmp_buf, start, seg_len);
140  tmp_buf = (uint8_t*)tmp_buf + seg_len;
141 // memory barrier needed for SMP here in theory
142 
143  start += seg_len - (f->end - f->buffer);
144  len -= seg_len;
145  } while (len > 0);
146 
147  return *wrap_buf;
148 }
149 
150 /**
151  * Return a pointer in the fifo buffer where the offset starts at until
152  * the wrap point or end of request.
153  * len will contain the valid length of the returned buffer.
154  * A second call to flac_fifo_read (with new offset and len) should be called
155  * to get the post-wrap buf if the returned len is less than the requested.
156  **/
158 {
159  AVFifoBuffer *f = fpc->fifo_buf;
160  uint8_t *start = f->rptr + offset;
161 
162  if (start >= f->end)
163  start -= f->end - f->buffer;
164  *len = FFMIN(*len, f->end - start);
165  return start;
166 }
167 
169 {
171  uint8_t *header_buf;
172  int size = 0;
173  header_buf = flac_fifo_read_wrap(fpc, offset,
175  &fpc->wrap_buf,
177  if (frame_header_is_valid(fpc->avctx, header_buf, &fi)) {
178  FLACHeaderMarker **end_handle = &fpc->headers;
179  int i;
180 
181  size = 0;
182  while (*end_handle) {
183  end_handle = &(*end_handle)->next;
184  size++;
185  }
186 
187  *end_handle = av_mallocz(sizeof(**end_handle));
188  if (!*end_handle) {
189  av_log(fpc->avctx, AV_LOG_ERROR,
190  "couldn't allocate FLACHeaderMarker\n");
191  return AVERROR(ENOMEM);
192  }
193  (*end_handle)->fi = fi;
194  (*end_handle)->offset = offset;
195 
196  for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++)
197  (*end_handle)->link_penalty[i] = FLAC_HEADER_NOT_PENALIZED_YET;
198 
199  fpc->nb_headers_found++;
200  size++;
201  }
202  return size;
203 }
204 
206  int buf_size, int search_start)
207 {
208  int size = 0, mod_offset = (buf_size - 1) % 4, i, j;
209  uint32_t x;
210 
211  for (i = 0; i < mod_offset; i++) {
212  if ((AV_RB16(buf + i) & 0xFFFE) == 0xFFF8) {
213  int ret = find_headers_search_validate(fpc, search_start + i);
214  size = FFMAX(size, ret);
215  }
216  }
217 
218  for (; i < buf_size - 1; i += 4) {
219  x = AV_RN32(buf + i);
220  if (((x & ~(x + 0x01010101)) & 0x80808080)) {
221  for (j = 0; j < 4; j++) {
222  if ((AV_RB16(buf + i + j) & 0xFFFE) == 0xFFF8) {
223  int ret = find_headers_search_validate(fpc, search_start + i + j);
224  size = FFMAX(size, ret);
225  }
226  }
227  }
228  }
229  return size;
230 }
231 
232 static int find_new_headers(FLACParseContext *fpc, int search_start)
233 {
235  int search_end, size = 0, read_len, temp;
236  uint8_t *buf;
237  fpc->nb_headers_found = 0;
238 
239  /* Search for a new header of at most 16 bytes. */
240  search_end = av_fifo_size(fpc->fifo_buf) - (MAX_FRAME_HEADER_SIZE - 1);
241  read_len = search_end - search_start + 1;
242  buf = flac_fifo_read(fpc, search_start, &read_len);
243  size = find_headers_search(fpc, buf, read_len, search_start);
244  search_start += read_len - 1;
245 
246  /* If fifo end was hit do the wrap around. */
247  if (search_start != search_end) {
248  uint8_t wrap[2];
249 
250  wrap[0] = buf[read_len - 1];
251  /* search_start + 1 is the post-wrap offset in the fifo. */
252  read_len = search_end - (search_start + 1) + 1;
253 
254  buf = flac_fifo_read(fpc, search_start + 1, &read_len);
255  wrap[1] = buf[0];
256 
257  if ((AV_RB16(wrap) & 0xFFFE) == 0xFFF8) {
258  temp = find_headers_search_validate(fpc, search_start);
259  size = FFMAX(size, temp);
260  }
261  search_start++;
262 
263  /* Continue to do the last half of the wrap. */
264  temp = find_headers_search(fpc, buf, read_len, search_start);
265  size = FFMAX(size, temp);
266  search_start += read_len - 1;
267  }
268 
269  /* Return the size even if no new headers were found. */
270  if (!size && fpc->headers)
271  for (end = fpc->headers; end; end = end->next)
272  size++;
273  return size;
274 }
275 
277  FLACFrameInfo *header_fi,
278  FLACFrameInfo *child_fi,
279  int log_level_offset)
280 {
281  int deduction = 0;
282  if (child_fi->samplerate != header_fi->samplerate) {
283  deduction += FLAC_HEADER_CHANGED_PENALTY;
284  av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
285  "sample rate change detected in adjacent frames\n");
286  }
287  if (child_fi->bps != header_fi->bps) {
288  deduction += FLAC_HEADER_CHANGED_PENALTY;
289  av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
290  "bits per sample change detected in adjacent frames\n");
291  }
292  if (child_fi->is_var_size != header_fi->is_var_size) {
293  /* Changing blocking strategy not allowed per the spec */
294  deduction += FLAC_HEADER_BASE_SCORE;
295  av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
296  "blocking strategy change detected in adjacent frames\n");
297  }
298  if (child_fi->channels != header_fi->channels) {
299  deduction += FLAC_HEADER_CHANGED_PENALTY;
300  av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
301  "number of channels change detected in adjacent frames\n");
302  }
303  return deduction;
304 }
305 
308  FLACHeaderMarker *child,
309  int log_level_offset)
310 {
311  FLACFrameInfo *header_fi = &header->fi, *child_fi = &child->fi;
312  int deduction, deduction_expected = 0, i;
313  deduction = check_header_fi_mismatch(fpc, header_fi, child_fi,
314  log_level_offset);
315  /* Check sample and frame numbers. */
316  if ((child_fi->frame_or_sample_num - header_fi->frame_or_sample_num
317  != header_fi->blocksize) &&
318  (child_fi->frame_or_sample_num
319  != header_fi->frame_or_sample_num + 1)) {
320  FLACHeaderMarker *curr;
321  int64_t expected_frame_num, expected_sample_num;
322  /* If there are frames in the middle we expect this deduction,
323  as they are probably valid and this one follows it */
324 
325  expected_frame_num = expected_sample_num = header_fi->frame_or_sample_num;
326  curr = header;
327  while (curr != child) {
328  /* Ignore frames that failed all crc checks */
329  for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++) {
331  expected_frame_num++;
332  expected_sample_num += curr->fi.blocksize;
333  break;
334  }
335  }
336  curr = curr->next;
337  }
338 
339  if (expected_frame_num == child_fi->frame_or_sample_num ||
340  expected_sample_num == child_fi->frame_or_sample_num)
341  deduction_expected = deduction ? 0 : 1;
342 
343  deduction += FLAC_HEADER_CHANGED_PENALTY;
344  av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
345  "sample/frame number mismatch in adjacent frames\n");
346  }
347 
348  /* If we have suspicious headers, check the CRC between them */
349  if (deduction && !deduction_expected) {
350  FLACHeaderMarker *curr;
351  int read_len;
352  uint8_t *buf;
353  uint32_t crc = 1;
354  int inverted_test = 0;
355 
356  /* Since CRC is expensive only do it if we haven't yet.
357  This assumes a CRC penalty is greater than all other check penalties */
358  curr = header->next;
359  for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS && curr != child; i++)
360  curr = curr->next;
361 
364  FLACHeaderMarker *start, *end;
365 
366  /* Although overlapping chains are scored, the crc should never
367  have to be computed twice for a single byte. */
368  start = header;
369  end = child;
370  if (i > 0 &&
371  header->link_penalty[i - 1] >= FLAC_HEADER_CRC_FAIL_PENALTY) {
372  while (start->next != child)
373  start = start->next;
374  inverted_test = 1;
375  } else if (i > 0 &&
376  header->next->link_penalty[i-1] >=
378  end = header->next;
379  inverted_test = 1;
380  }
381 
382  read_len = end->offset - start->offset;
383  buf = flac_fifo_read(fpc, start->offset, &read_len);
384  crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf, read_len);
385  read_len = (end->offset - start->offset) - read_len;
386 
387  if (read_len) {
388  buf = flac_fifo_read(fpc, end->offset - read_len, &read_len);
389  crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), crc, buf, read_len);
390  }
391  }
392 
393  if (!crc ^ !inverted_test) {
394  deduction += FLAC_HEADER_CRC_FAIL_PENALTY;
395  av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
396  "crc check failed from offset %i (frame %"PRId64") to %i (frame %"PRId64")\n",
397  header->offset, header_fi->frame_or_sample_num,
398  child->offset, child_fi->frame_or_sample_num);
399  }
400  }
401  return deduction;
402 }
403 
404 /**
405  * Score a header.
406  *
407  * Give FLAC_HEADER_BASE_SCORE points to a frame for existing.
408  * If it has children, (subsequent frames of which the preceding CRC footer
409  * validates against this one,) then take the maximum score of the children,
410  * with a penalty of FLAC_HEADER_CHANGED_PENALTY applied for each change to
411  * bps, sample rate, channels, but not decorrelation mode, or blocksize,
412  * because it can change often.
413  **/
415 {
416  FLACHeaderMarker *child;
417  int dist = 0;
418  int child_score;
419  int base_score = FLAC_HEADER_BASE_SCORE;
420  if (header->max_score != FLAC_HEADER_NOT_SCORED_YET)
421  return header->max_score;
422 
423  /* Modify the base score with changes from the last output header */
424  if (fpc->last_fi_valid) {
425  /* Silence the log since this will be repeated if selected */
426  base_score -= check_header_fi_mismatch(fpc, &fpc->last_fi, &header->fi,
427  AV_LOG_DEBUG);
428  }
429 
430  header->max_score = base_score;
431 
432  /* Check and compute the children's scores. */
433  child = header->next;
434  for (dist = 0; dist < FLAC_MAX_SEQUENTIAL_HEADERS && child; dist++) {
435  /* Look at the child's frame header info and penalize suspicious
436  changes between the headers. */
437  if (header->link_penalty[dist] == FLAC_HEADER_NOT_PENALIZED_YET) {
438  header->link_penalty[dist] = check_header_mismatch(fpc, header,
439  child, AV_LOG_DEBUG);
440  }
441  child_score = score_header(fpc, child) - header->link_penalty[dist];
442 
443  if (FLAC_HEADER_BASE_SCORE + child_score > header->max_score) {
444  /* Keep the child because the frame scoring is dynamic. */
445  header->best_child = child;
446  header->max_score = base_score + child_score;
447  }
448  child = child->next;
449  }
450 
451  return header->max_score;
452 }
453 
455 {
456  FLACHeaderMarker *curr;
457  int best_score = 0;//FLAC_HEADER_NOT_SCORED_YET;
458  /* First pass to clear all old scores. */
459  for (curr = fpc->headers; curr; curr = curr->next)
461 
462  /* Do a second pass to score them all. */
463  for (curr = fpc->headers; curr; curr = curr->next) {
464  if (score_header(fpc, curr) > best_score) {
465  fpc->best_header = curr;
466  best_score = curr->max_score;
467  }
468  }
469 }
470 
471 static int get_best_header(FLACParseContext *fpc, const uint8_t **poutbuf,
472  int *poutbuf_size)
473 {
475  FLACHeaderMarker *child = header->best_child;
476  if (!child) {
477  *poutbuf_size = av_fifo_size(fpc->fifo_buf) - header->offset;
478  } else {
479  *poutbuf_size = child->offset - header->offset;
480 
481  /* If the child has suspicious changes, log them */
482  check_header_mismatch(fpc, header, child, 0);
483  }
484 
485  if (header->fi.channels != fpc->avctx->channels ||
486  !fpc->avctx->channel_layout) {
487  fpc->avctx->channels = header->fi.channels;
489  }
490  fpc->avctx->sample_rate = header->fi.samplerate;
491  fpc->pc->duration = header->fi.blocksize;
492  *poutbuf = flac_fifo_read_wrap(fpc, header->offset, *poutbuf_size,
493  &fpc->wrap_buf,
495 
496 
497  if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS) {
498  if (header->fi.is_var_size)
499  fpc->pc->pts = header->fi.frame_or_sample_num;
500  else if (header->best_child)
501  fpc->pc->pts = header->fi.frame_or_sample_num * header->fi.blocksize;
502  }
503 
504  fpc->best_header_valid = 0;
505  fpc->last_fi_valid = 1;
506  fpc->last_fi = header->fi;
507 
508  /* Return the negative overread index so the client can compute pos.
509  This should be the amount overread to the beginning of the child */
510  if (child)
511  return child->offset - av_fifo_size(fpc->fifo_buf);
512  return 0;
513 }
514 
516  const uint8_t **poutbuf, int *poutbuf_size,
517  const uint8_t *buf, int buf_size)
518 {
519  FLACParseContext *fpc = s->priv_data;
520  FLACHeaderMarker *curr;
521  int nb_headers;
522  const uint8_t *read_end = buf;
523  const uint8_t *read_start = buf;
524 
527  if (frame_header_is_valid(avctx, buf, &fi)) {
528  s->duration = fi.blocksize;
529  if (!avctx->sample_rate)
530  avctx->sample_rate = fi.samplerate;
531  if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS) {
532  fpc->pc->pts = fi.frame_or_sample_num;
533  if (!fi.is_var_size)
534  fpc->pc->pts *= fi.blocksize;
535  }
536  }
537  *poutbuf = buf;
538  *poutbuf_size = buf_size;
539  return buf_size;
540  }
541 
542  fpc->avctx = avctx;
543  if (fpc->best_header_valid)
544  return get_best_header(fpc, poutbuf, poutbuf_size);
545 
546  /* If a best_header was found last call remove it with the buffer data. */
547  if (fpc->best_header && fpc->best_header->best_child) {
550 
551  /* Remove headers in list until the end of the best_header. */
552  for (curr = fpc->headers; curr != best_child; curr = temp) {
553  if (curr != fpc->best_header) {
554  av_log(avctx, AV_LOG_DEBUG,
555  "dropping low score %i frame header from offset %i to %i\n",
556  curr->max_score, curr->offset, curr->next->offset);
557  }
558  temp = curr->next;
559  av_free(curr);
560  fpc->nb_headers_buffered--;
561  }
562  /* Release returned data from ring buffer. */
563  av_fifo_drain(fpc->fifo_buf, best_child->offset);
564 
565  /* Fix the offset for the headers remaining to match the new buffer. */
566  for (curr = best_child->next; curr; curr = curr->next)
567  curr->offset -= best_child->offset;
568 
569  best_child->offset = 0;
570  fpc->headers = best_child;
572  fpc->best_header = best_child;
573  return get_best_header(fpc, poutbuf, poutbuf_size);
574  }
575  fpc->best_header = NULL;
576  } else if (fpc->best_header) {
577  /* No end frame no need to delete the buffer; probably eof */
579 
580  for (curr = fpc->headers; curr != fpc->best_header; curr = temp) {
581  temp = curr->next;
582  av_free(curr);
583  fpc->nb_headers_buffered--;
584  }
585  fpc->headers = fpc->best_header->next;
586  av_freep(&fpc->best_header);
587  fpc->nb_headers_buffered--;
588  }
589 
590  /* Find and score new headers. */
591  /* buf_size is zero when flushing, so check for this since we do */
592  /* not want to try to read more input once we have found the end. */
593  /* Also note that buf can't be NULL. */
594  while ((buf_size && read_end < buf + buf_size &&
596  || (!buf_size && !fpc->end_padded)) {
597  int start_offset;
598 
599  /* Pad the end once if EOF, to check the final region for headers. */
600  if (!buf_size) {
601  fpc->end_padded = 1;
602  read_end = read_start + MAX_FRAME_HEADER_SIZE;
603  } else {
604  /* The maximum read size is the upper-bound of what the parser
605  needs to have the required number of frames buffered */
606  int nb_desired = FLAC_MIN_HEADERS - fpc->nb_headers_buffered + 1;
607  read_end = read_end + FFMIN(buf + buf_size - read_end,
608  nb_desired * FLAC_AVG_FRAME_SIZE);
609  }
610 
611  if (!av_fifo_space(fpc->fifo_buf) &&
613  fpc->nb_headers_buffered * 20) {
614  /* There is less than one valid flac header buffered for 20 headers
615  * buffered. Therefore the fifo is most likely filled with invalid
616  * data and the input is not a flac file. */
617  goto handle_error;
618  }
619 
620  /* Fill the buffer. */
621  if ( av_fifo_space(fpc->fifo_buf) < read_end - read_start
622  && av_fifo_realloc2(fpc->fifo_buf, (read_end - read_start) + 2*av_fifo_size(fpc->fifo_buf)) < 0) {
623  av_log(avctx, AV_LOG_ERROR,
624  "couldn't reallocate buffer of size %"PTRDIFF_SPECIFIER"\n",
625  (read_end - read_start) + av_fifo_size(fpc->fifo_buf));
626  goto handle_error;
627  }
628 
629  if (buf_size) {
630  av_fifo_generic_write(fpc->fifo_buf, (void*) read_start,
631  read_end - read_start, NULL);
632  } else {
633  int8_t pad[MAX_FRAME_HEADER_SIZE] = { 0 };
634  av_fifo_generic_write(fpc->fifo_buf, pad, sizeof(pad), NULL);
635  }
636 
637  /* Tag headers and update sequences. */
638  start_offset = av_fifo_size(fpc->fifo_buf) -
639  ((read_end - read_start) + (MAX_FRAME_HEADER_SIZE - 1));
640  start_offset = FFMAX(0, start_offset);
641  nb_headers = find_new_headers(fpc, start_offset);
642 
643  if (nb_headers < 0) {
644  av_log(avctx, AV_LOG_ERROR,
645  "find_new_headers couldn't allocate FLAC header\n");
646  goto handle_error;
647  }
648 
649  fpc->nb_headers_buffered = nb_headers;
650  /* Wait till FLAC_MIN_HEADERS to output a valid frame. */
651  if (!fpc->end_padded && fpc->nb_headers_buffered < FLAC_MIN_HEADERS) {
652  if (read_end < buf + buf_size) {
653  read_start = read_end;
654  continue;
655  } else {
656  goto handle_error;
657  }
658  }
659 
660  /* If headers found, update the scores since we have longer chains. */
661  if (fpc->end_padded || fpc->nb_headers_found)
662  score_sequences(fpc);
663 
664  /* restore the state pre-padding */
665  if (fpc->end_padded) {
666  int warp = fpc->fifo_buf->wptr - fpc->fifo_buf->buffer < MAX_FRAME_HEADER_SIZE;
667  /* HACK: drain the tail of the fifo */
670  if (warp) {
671  fpc->fifo_buf->wptr += fpc->fifo_buf->end -
672  fpc->fifo_buf->buffer;
673  }
674  read_start = read_end = NULL;
675  }
676  }
677 
678  for (curr = fpc->headers; curr; curr = curr->next) {
679  if (!fpc->best_header || curr->max_score > fpc->best_header->max_score) {
680  fpc->best_header = curr;
681  }
682  }
683 
684  if (fpc->best_header && fpc->best_header->max_score <= 0) {
685  // Only accept a bad header if there is no other option to continue
686  if (!buf_size || read_end != buf || fpc->nb_headers_buffered < FLAC_MIN_HEADERS)
687  fpc->best_header = NULL;
688  }
689 
690  if (fpc->best_header) {
691  fpc->best_header_valid = 1;
692  if (fpc->best_header->offset > 0) {
693  /* Output a junk frame. */
694  av_log(avctx, AV_LOG_DEBUG, "Junk frame till offset %i\n",
695  fpc->best_header->offset);
696 
697  /* Set duration to 0. It is unknown or invalid in a junk frame. */
698  s->duration = 0;
699  *poutbuf_size = fpc->best_header->offset;
700  *poutbuf = flac_fifo_read_wrap(fpc, 0, *poutbuf_size,
701  &fpc->wrap_buf,
703  return buf_size ? (read_end - buf) : (fpc->best_header->offset -
704  av_fifo_size(fpc->fifo_buf));
705  }
706  if (!buf_size)
707  return get_best_header(fpc, poutbuf, poutbuf_size);
708  }
709 
710 handle_error:
711  *poutbuf = NULL;
712  *poutbuf_size = 0;
713  return buf_size ? read_end - buf : 0;
714 }
715 
717 {
718  FLACParseContext *fpc = c->priv_data;
719  fpc->pc = c;
720  /* There will generally be FLAC_MIN_HEADERS buffered in the fifo before
721  it drains. This is allocated early to avoid slow reallocation. */
723  if (!fpc->fifo_buf) {
724  av_log(fpc->avctx, AV_LOG_ERROR,
725  "couldn't allocate fifo_buf\n");
726  return AVERROR(ENOMEM);
727  }
728  return 0;
729 }
730 
732 {
733  FLACParseContext *fpc = c->priv_data;
734  FLACHeaderMarker *curr = fpc->headers, *temp;
735 
736  while (curr) {
737  temp = curr->next;
738  av_free(curr);
739  curr = temp;
740  }
741  fpc->headers = NULL;
742  av_fifo_freep(&fpc->fifo_buf);
743  av_freep(&fpc->wrap_buf);
744 }
745 
748  .priv_data_size = sizeof(FLACParseContext),
749  .parser_init = flac_parse_init,
750  .parser_parse = flac_parse,
751  .parser_close = flac_parse_close,
752 };
static int frame_header_is_valid(AVCodecContext *avctx, const uint8_t *buf, FLACFrameInfo *fi)
Definition: flac_parser.c:96
#define NULL
Definition: coverity.c:32
static void score_sequences(FLACParseContext *fpc)
Definition: flac_parser.c:454
int size
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:87
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:78
int best_header_valid
flag set when the parser returns junk; if set return best_header next time
Definition: flac_parser.c:85
#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:92
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:82
#define f(width, name)
Definition: cbs_vp9.c:255
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:92
int wrap_buf_allocated_size
actual allocated size of the buffer
Definition: flac_parser.c:91
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:471
#define FLAC_HEADER_CHANGED_PENALTY
Definition: flac_parser.c:51
static void flac_parse_close(AVCodecParserContext *c)
Definition: flac_parser.c:731
#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:515
#define av_log(a,...)
#define MAX_FRAME_VERIFY_SIZE
Definition: flac_parser.c:58
#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:263
static int check_header_fi_mismatch(FLACParseContext *fpc, FLACFrameInfo *header_fi, FLACFrameInfo *child_fi, int log_level_offset)
Definition: flac_parser.c:276
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:237
#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:89
struct FLACHeaderMarker * next
next CRC-8 verified header that immediately follows this one in the bytestream
Definition: flac_parser.c:68
#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:79
#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:478
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:117
int last_fi_valid
set if last_fi is valid
Definition: flac_parser.c:93
int max_score
maximum score found after checking each child that has a valid CRC
Definition: flac_parser.c:65
static int find_headers_search_validate(FLACParseContext *fpc, int offset)
Definition: flac_parser.c:168
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:90
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:232
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:414
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:67
#define AV_RN32(p)
Definition: intreadwrite.h:364
int nb_headers_buffered
number of headers that are buffered
Definition: flac_parser.c:84
#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:77
FLACHeaderMarker * best_header
highest scoring header within buffer
Definition: flac_parser.c:81
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:746
const AVCRC * av_crc_get_table(AVCRCId crc_id)
Get an initialized standard CRC table.
Definition: crc.c:374
if(ret< 0)
Definition: vf_mcdeint.c:279
static int find_headers_search(FLACParseContext *fpc, uint8_t *buf, int buf_size, int search_start)
Definition: flac_parser.c:205
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:61
#define AV_INPUT_BUFFER_PADDING_SIZE
Required number of additionally allocated bytes at the end of the input bitstream for decoding...
Definition: avcodec.h:215
#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:716
#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:62
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:157
#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:71
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:306