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path: root/libavcodec/flac_parser.c (plain)
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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
59typedef struct FLACHeaderMarker {
60 int offset; /**< byte offset from start of FLACParseContext->buffer */
61 int *link_penalty; /**< pointer to array of local scores between this header
62 and the one at a distance equal array position */
63 int max_score; /**< maximum score found after checking each child that
64 has a valid CRC */
65 FLACFrameInfo fi; /**< decoded frame header info */
66 struct FLACHeaderMarker *next; /**< next CRC-8 verified header that
67 immediately follows this one in
68 the bytestream */
69 struct FLACHeaderMarker *best_child; /**< following frame header with
70 which this frame has the best
71 score with */
72} FLACHeaderMarker;
73
74typedef struct FLACParseContext {
75 AVCodecParserContext *pc; /**< parent context */
76 AVCodecContext *avctx; /**< codec context pointer for logging */
77 FLACHeaderMarker *headers; /**< linked-list that starts at the first
78 CRC-8 verified header within buffer */
79 FLACHeaderMarker *best_header; /**< highest scoring header within buffer */
80 int nb_headers_found; /**< number of headers found in the last
81 flac_parse() call */
82 int nb_headers_buffered; /**< number of headers that are buffered */
83 int best_header_valid; /**< flag set when the parser returns junk;
84 if set return best_header next time */
85 AVFifoBuffer *fifo_buf; /**< buffer to store all data until headers
86 can be verified */
87 int end_padded; /**< specifies if fifo_buf's end is padded */
88 uint8_t *wrap_buf; /**< general fifo read buffer when wrapped */
89 int wrap_buf_allocated_size; /**< actual allocated size of the buffer */
90 FLACFrameInfo last_fi; /**< last decoded frame header info */
91 int last_fi_valid; /**< set if last_fi is valid */
92} FLACParseContext;
93
94static int frame_header_is_valid(AVCodecContext *avctx, const uint8_t *buf,
95 FLACFrameInfo *fi)
96{
97 GetBitContext gb;
98 init_get_bits(&gb, buf, MAX_FRAME_HEADER_SIZE * 8);
99 return !ff_flac_decode_frame_header(avctx, &gb, fi, 127);
100}
101
102/**
103 * Non-destructive fast fifo pointer fetching
104 * Returns a pointer from the specified offset.
105 * If possible the pointer points within the fifo buffer.
106 * Otherwise (if it would cause a wrap around,) a pointer to a user-specified
107 * buffer is used.
108 * The pointer can be NULL. In any case it will be reallocated to hold the size.
109 * If the returned pointer will be used after subsequent calls to flac_fifo_read_wrap
110 * then the subsequent calls should pass in a different wrap_buf so as to not
111 * overwrite the contents of the previous wrap_buf.
112 * This function is based on av_fifo_generic_read, which is why there is a comment
113 * about a memory barrier for SMP.
114 */
115static uint8_t* flac_fifo_read_wrap(FLACParseContext *fpc, int offset, int len,
116 uint8_t** wrap_buf, int* allocated_size)
117{
118 AVFifoBuffer *f = fpc->fifo_buf;
119 uint8_t *start = f->rptr + offset;
120 uint8_t *tmp_buf;
121
122 if (start >= f->end)
123 start -= f->end - f->buffer;
124 if (f->end - start >= len)
125 return start;
126
127 tmp_buf = av_fast_realloc(*wrap_buf, allocated_size, len);
128
129 if (!tmp_buf) {
130 av_log(fpc->avctx, AV_LOG_ERROR,
131 "couldn't reallocate wrap buffer of size %d", len);
132 return NULL;
133 }
134 *wrap_buf = tmp_buf;
135 do {
136 int seg_len = FFMIN(f->end - start, len);
137 memcpy(tmp_buf, start, seg_len);
138 tmp_buf = (uint8_t*)tmp_buf + seg_len;
139// memory barrier needed for SMP here in theory
140
141 start += seg_len - (f->end - f->buffer);
142 len -= seg_len;
143 } while (len > 0);
144
145 return *wrap_buf;
146}
147
148/**
149 * Return a pointer in the fifo buffer where the offset starts at until
150 * the wrap point or end of request.
151 * len will contain the valid length of the returned buffer.
152 * A second call to flac_fifo_read (with new offset and len) should be called
153 * to get the post-wrap buf if the returned len is less than the requested.
154 **/
155static uint8_t* flac_fifo_read(FLACParseContext *fpc, int offset, int *len)
156{
157 AVFifoBuffer *f = fpc->fifo_buf;
158 uint8_t *start = f->rptr + offset;
159
160 if (start >= f->end)
161 start -= f->end - f->buffer;
162 *len = FFMIN(*len, f->end - start);
163 return start;
164}
165
166static int find_headers_search_validate(FLACParseContext *fpc, int offset)
167{
168 FLACFrameInfo fi;
169 uint8_t *header_buf;
170 int size = 0;
171 header_buf = flac_fifo_read_wrap(fpc, offset,
172 MAX_FRAME_HEADER_SIZE,
173 &fpc->wrap_buf,
174 &fpc->wrap_buf_allocated_size);
175 if (frame_header_is_valid(fpc->avctx, header_buf, &fi)) {
176 FLACHeaderMarker **end_handle = &fpc->headers;
177 int i;
178
179 size = 0;
180 while (*end_handle) {
181 end_handle = &(*end_handle)->next;
182 size++;
183 }
184
185 *end_handle = av_mallocz(sizeof(**end_handle));
186 if (!*end_handle) {
187 av_log(fpc->avctx, AV_LOG_ERROR,
188 "couldn't allocate FLACHeaderMarker\n");
189 return AVERROR(ENOMEM);
190 }
191 (*end_handle)->fi = fi;
192 (*end_handle)->offset = offset;
193 (*end_handle)->link_penalty = av_malloc(sizeof(int) *
194 FLAC_MAX_SEQUENTIAL_HEADERS);
195 if (!(*end_handle)->link_penalty) {
196 av_freep(end_handle);
197 av_log(fpc->avctx, AV_LOG_ERROR,
198 "couldn't allocate link_penalty\n");
199 return AVERROR(ENOMEM);
200 }
201
202 for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++)
203 (*end_handle)->link_penalty[i] = FLAC_HEADER_NOT_PENALIZED_YET;
204
205 fpc->nb_headers_found++;
206 size++;
207 }
208 return size;
209}
210
211static int find_headers_search(FLACParseContext *fpc, uint8_t *buf, int buf_size,
212 int search_start)
213
214{
215 int size = 0, mod_offset = (buf_size - 1) % 4, i, j;
216 uint32_t x;
217
218 for (i = 0; i < mod_offset; i++) {
219 if ((AV_RB16(buf + i) & 0xFFFE) == 0xFFF8)
220 size = find_headers_search_validate(fpc, search_start + i);
221 }
222
223 for (; i < buf_size - 1; i += 4) {
224 x = AV_RB32(buf + i);
225 if (((x & ~(x + 0x01010101)) & 0x80808080)) {
226 for (j = 0; j < 4; j++) {
227 if ((AV_RB16(buf + i + j) & 0xFFFE) == 0xFFF8)
228 size = find_headers_search_validate(fpc, search_start + i + j);
229 }
230 }
231 }
232 return size;
233}
234
235static int find_new_headers(FLACParseContext *fpc, int search_start)
236{
237 FLACHeaderMarker *end;
238 int search_end, size = 0, read_len, temp;
239 uint8_t *buf;
240 fpc->nb_headers_found = 0;
241
242 /* Search for a new header of at most 16 bytes. */
243 search_end = av_fifo_size(fpc->fifo_buf) - (MAX_FRAME_HEADER_SIZE - 1);
244 read_len = search_end - search_start + 1;
245 buf = flac_fifo_read(fpc, search_start, &read_len);
246 size = find_headers_search(fpc, buf, read_len, search_start);
247 search_start += read_len - 1;
248
249 /* If fifo end was hit do the wrap around. */
250 if (search_start != search_end) {
251 uint8_t wrap[2];
252
253 wrap[0] = buf[read_len - 1];
254 read_len = search_end - search_start + 1;
255
256 /* search_start + 1 is the post-wrap offset in the fifo. */
257 buf = flac_fifo_read(fpc, search_start + 1, &read_len);
258 wrap[1] = buf[0];
259
260 if ((AV_RB16(wrap) & 0xFFFE) == 0xFFF8) {
261 temp = find_headers_search_validate(fpc, search_start);
262 size = FFMAX(size, temp);
263 }
264 search_start++;
265
266 /* Continue to do the last half of the wrap. */
267 temp = find_headers_search(fpc, buf, read_len, search_start);
268 size = FFMAX(size, temp);
269 search_start += read_len - 1;
270 }
271
272 /* Return the size even if no new headers were found. */
273 if (!size && fpc->headers)
274 for (end = fpc->headers; end; end = end->next)
275 size++;
276 return size;
277}
278
279static int check_header_fi_mismatch(FLACParseContext *fpc,
280 FLACFrameInfo *header_fi,
281 FLACFrameInfo *child_fi,
282 int log_level_offset)
283{
284 int deduction = 0;
285 if (child_fi->samplerate != header_fi->samplerate) {
286 deduction += FLAC_HEADER_CHANGED_PENALTY;
287 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
288 "sample rate change detected in adjacent frames\n");
289 }
290 if (child_fi->bps != header_fi->bps) {
291 deduction += FLAC_HEADER_CHANGED_PENALTY;
292 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
293 "bits per sample change detected in adjacent frames\n");
294 }
295 if (child_fi->is_var_size != header_fi->is_var_size) {
296 /* Changing blocking strategy not allowed per the spec */
297 deduction += FLAC_HEADER_BASE_SCORE;
298 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
299 "blocking strategy change detected in adjacent frames\n");
300 }
301 if (child_fi->channels != header_fi->channels) {
302 deduction += FLAC_HEADER_CHANGED_PENALTY;
303 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
304 "number of channels change detected in adjacent frames\n");
305 }
306 return deduction;
307}
308
309static int check_header_mismatch(FLACParseContext *fpc,
310 FLACHeaderMarker *header,
311 FLACHeaderMarker *child,
312 int log_level_offset)
313{
314 FLACFrameInfo *header_fi = &header->fi, *child_fi = &child->fi;
315 int deduction, deduction_expected = 0, i;
316 deduction = check_header_fi_mismatch(fpc, header_fi, child_fi,
317 log_level_offset);
318 /* Check sample and frame numbers. */
319 if ((child_fi->frame_or_sample_num - header_fi->frame_or_sample_num
320 != header_fi->blocksize) &&
321 (child_fi->frame_or_sample_num
322 != header_fi->frame_or_sample_num + 1)) {
323 FLACHeaderMarker *curr;
324 int expected_frame_num, expected_sample_num;
325 /* If there are frames in the middle we expect this deduction,
326 as they are probably valid and this one follows it */
327
328 expected_frame_num = expected_sample_num = header_fi->frame_or_sample_num;
329 curr = header;
330 while (curr != child) {
331 /* Ignore frames that failed all crc checks */
332 for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++) {
333 if (curr->link_penalty[i] < FLAC_HEADER_CRC_FAIL_PENALTY) {
334 expected_frame_num++;
335 expected_sample_num += curr->fi.blocksize;
336 break;
337 }
338 }
339 curr = curr->next;
340 }
341
342 if (expected_frame_num == child_fi->frame_or_sample_num ||
343 expected_sample_num == child_fi->frame_or_sample_num)
344 deduction_expected = deduction ? 0 : 1;
345
346 deduction += FLAC_HEADER_CHANGED_PENALTY;
347 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
348 "sample/frame number mismatch in adjacent frames\n");
349 }
350
351 /* If we have suspicious headers, check the CRC between them */
352 if (deduction && !deduction_expected) {
353 FLACHeaderMarker *curr;
354 int read_len;
355 uint8_t *buf;
356 uint32_t crc = 1;
357 int inverted_test = 0;
358
359 /* Since CRC is expensive only do it if we haven't yet.
360 This assumes a CRC penalty is greater than all other check penalties */
361 curr = header->next;
362 for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS && curr != child; i++)
363 curr = curr->next;
364
365 if (header->link_penalty[i] < FLAC_HEADER_CRC_FAIL_PENALTY ||
366 header->link_penalty[i] == FLAC_HEADER_NOT_PENALIZED_YET) {
367 FLACHeaderMarker *start, *end;
368
369 /* Although overlapping chains are scored, the crc should never
370 have to be computed twice for a single byte. */
371 start = header;
372 end = child;
373 if (i > 0 &&
374 header->link_penalty[i - 1] >= FLAC_HEADER_CRC_FAIL_PENALTY) {
375 while (start->next != child)
376 start = start->next;
377 inverted_test = 1;
378 } else if (i > 0 &&
379 header->next->link_penalty[i-1] >=
380 FLAC_HEADER_CRC_FAIL_PENALTY ) {
381 end = header->next;
382 inverted_test = 1;
383 }
384
385 read_len = end->offset - start->offset;
386 buf = flac_fifo_read(fpc, start->offset, &read_len);
387 crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf, read_len);
388 read_len = (end->offset - start->offset) - read_len;
389
390 if (read_len) {
391 buf = flac_fifo_read(fpc, end->offset - read_len, &read_len);
392 crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), crc, buf, read_len);
393 }
394 }
395
396 if (!crc ^ !inverted_test) {
397 deduction += FLAC_HEADER_CRC_FAIL_PENALTY;
398 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
399 "crc check failed from offset %i (frame %"PRId64") to %i (frame %"PRId64")\n",
400 header->offset, header_fi->frame_or_sample_num,
401 child->offset, child_fi->frame_or_sample_num);
402 }
403 }
404 return deduction;
405}
406
407/**
408 * Score a header.
409 *
410 * Give FLAC_HEADER_BASE_SCORE points to a frame for existing.
411 * If it has children, (subsequent frames of which the preceding CRC footer
412 * validates against this one,) then take the maximum score of the children,
413 * with a penalty of FLAC_HEADER_CHANGED_PENALTY applied for each change to
414 * bps, sample rate, channels, but not decorrelation mode, or blocksize,
415 * because it can change often.
416 **/
417static int score_header(FLACParseContext *fpc, FLACHeaderMarker *header)
418{
419 FLACHeaderMarker *child;
420 int dist = 0;
421 int child_score;
422 int base_score = FLAC_HEADER_BASE_SCORE;
423 if (header->max_score != FLAC_HEADER_NOT_SCORED_YET)
424 return header->max_score;
425
426 /* Modify the base score with changes from the last output header */
427 if (fpc->last_fi_valid) {
428 /* Silence the log since this will be repeated if selected */
429 base_score -= check_header_fi_mismatch(fpc, &fpc->last_fi, &header->fi,
430 AV_LOG_DEBUG);
431 }
432
433 header->max_score = base_score;
434
435 /* Check and compute the children's scores. */
436 child = header->next;
437 for (dist = 0; dist < FLAC_MAX_SEQUENTIAL_HEADERS && child; dist++) {
438 /* Look at the child's frame header info and penalize suspicious
439 changes between the headers. */
440 if (header->link_penalty[dist] == FLAC_HEADER_NOT_PENALIZED_YET) {
441 header->link_penalty[dist] = check_header_mismatch(fpc, header,
442 child, AV_LOG_DEBUG);
443 }
444 child_score = score_header(fpc, child) - header->link_penalty[dist];
445
446 if (FLAC_HEADER_BASE_SCORE + child_score > header->max_score) {
447 /* Keep the child because the frame scoring is dynamic. */
448 header->best_child = child;
449 header->max_score = base_score + child_score;
450 }
451 child = child->next;
452 }
453
454 return header->max_score;
455}
456
457static void score_sequences(FLACParseContext *fpc)
458{
459 FLACHeaderMarker *curr;
460 int best_score = 0;//FLAC_HEADER_NOT_SCORED_YET;
461 /* First pass to clear all old scores. */
462 for (curr = fpc->headers; curr; curr = curr->next)
463 curr->max_score = FLAC_HEADER_NOT_SCORED_YET;
464
465 /* Do a second pass to score them all. */
466 for (curr = fpc->headers; curr; curr = curr->next) {
467 if (score_header(fpc, curr) > best_score) {
468 fpc->best_header = curr;
469 best_score = curr->max_score;
470 }
471 }
472}
473
474static int get_best_header(FLACParseContext* fpc, const uint8_t **poutbuf,
475 int *poutbuf_size)
476{
477 FLACHeaderMarker *header = fpc->best_header;
478 FLACHeaderMarker *child = header->best_child;
479 if (!child) {
480 *poutbuf_size = av_fifo_size(fpc->fifo_buf) - header->offset;
481 } else {
482 *poutbuf_size = child->offset - header->offset;
483
484 /* If the child has suspicious changes, log them */
485 check_header_mismatch(fpc, header, child, 0);
486 }
487
488 if (header->fi.channels != fpc->avctx->channels ||
489 !fpc->avctx->channel_layout) {
490 fpc->avctx->channels = header->fi.channels;
491 ff_flac_set_channel_layout(fpc->avctx);
492 }
493 fpc->avctx->sample_rate = header->fi.samplerate;
494 fpc->pc->duration = header->fi.blocksize;
495 *poutbuf = flac_fifo_read_wrap(fpc, header->offset, *poutbuf_size,
496 &fpc->wrap_buf,
497 &fpc->wrap_buf_allocated_size);
498
499
500 if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS){
501 if (header->fi.is_var_size)
502 fpc->pc->pts = header->fi.frame_or_sample_num;
503 else if (header->best_child)
504 fpc->pc->pts = header->fi.frame_or_sample_num * header->fi.blocksize;
505 }
506
507 fpc->best_header_valid = 0;
508 fpc->last_fi_valid = 1;
509 fpc->last_fi = header->fi;
510
511 /* Return the negative overread index so the client can compute pos.
512 This should be the amount overread to the beginning of the child */
513 if (child)
514 return child->offset - av_fifo_size(fpc->fifo_buf);
515 return 0;
516}
517
518static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
519 const uint8_t **poutbuf, int *poutbuf_size,
520 const uint8_t *buf, int buf_size)
521{
522 FLACParseContext *fpc = s->priv_data;
523 FLACHeaderMarker *curr;
524 int nb_headers;
525 const uint8_t *read_end = buf;
526 const uint8_t *read_start = buf;
527
528 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
529 FLACFrameInfo fi;
530 if (frame_header_is_valid(avctx, buf, &fi)) {
531 s->duration = fi.blocksize;
532 if (!avctx->sample_rate)
533 avctx->sample_rate = fi.samplerate;
534 if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS){
535 fpc->pc->pts = fi.frame_or_sample_num;
536 if (!fi.is_var_size)
537 fpc->pc->pts *= fi.blocksize;
538 }
539 }
540 *poutbuf = buf;
541 *poutbuf_size = buf_size;
542 return buf_size;
543 }
544
545 fpc->avctx = avctx;
546 if (fpc->best_header_valid)
547 return get_best_header(fpc, poutbuf, poutbuf_size);
548
549 /* If a best_header was found last call remove it with the buffer data. */
550 if (fpc->best_header && fpc->best_header->best_child) {
551 FLACHeaderMarker *temp;
552 FLACHeaderMarker *best_child = fpc->best_header->best_child;
553
554 /* Remove headers in list until the end of the best_header. */
555 for (curr = fpc->headers; curr != best_child; curr = temp) {
556 if (curr != fpc->best_header) {
557 av_log(avctx, AV_LOG_DEBUG,
558 "dropping low score %i frame header from offset %i to %i\n",
559 curr->max_score, curr->offset, curr->next->offset);
560 }
561 temp = curr->next;
562 av_freep(&curr->link_penalty);
563 av_free(curr);
564 fpc->nb_headers_buffered--;
565 }
566 /* Release returned data from ring buffer. */
567 av_fifo_drain(fpc->fifo_buf, best_child->offset);
568
569 /* Fix the offset for the headers remaining to match the new buffer. */
570 for (curr = best_child->next; curr; curr = curr->next)
571 curr->offset -= best_child->offset;
572
573 fpc->nb_headers_buffered--;
574 best_child->offset = 0;
575 fpc->headers = best_child;
576 if (fpc->nb_headers_buffered >= FLAC_MIN_HEADERS) {
577 fpc->best_header = best_child;
578 return get_best_header(fpc, poutbuf, poutbuf_size);
579 }
580 fpc->best_header = NULL;
581 } else if (fpc->best_header) {
582 /* No end frame no need to delete the buffer; probably eof */
583 FLACHeaderMarker *temp;
584
585 for (curr = fpc->headers; curr != fpc->best_header; curr = temp) {
586 temp = curr->next;
587 av_freep(&curr->link_penalty);
588 av_free(curr);
589 fpc->nb_headers_buffered--;
590 }
591 fpc->headers = fpc->best_header->next;
592 av_freep(&fpc->best_header->link_penalty);
593 av_freep(&fpc->best_header);
594 fpc->nb_headers_buffered--;
595 }
596
597 /* Find and score new headers. */
598 /* buf_size is to zero when padding, so check for this since we do */
599 /* not want to try to read more input once we have found the end. */
600 /* Note that as (non-modified) parameters, buf can be non-NULL, */
601 /* while buf_size is 0. */
602 while ((buf && buf_size && read_end < buf + buf_size &&
603 fpc->nb_headers_buffered < FLAC_MIN_HEADERS)
604 || ((!buf || !buf_size) && !fpc->end_padded)) {
605 int start_offset;
606
607 /* Pad the end once if EOF, to check the final region for headers. */
608 if (!buf || !buf_size) {
609 fpc->end_padded = 1;
610 buf_size = MAX_FRAME_HEADER_SIZE;
611 read_end = read_start + MAX_FRAME_HEADER_SIZE;
612 } else {
613 /* The maximum read size is the upper-bound of what the parser
614 needs to have the required number of frames buffered */
615 int nb_desired = FLAC_MIN_HEADERS - fpc->nb_headers_buffered + 1;
616 read_end = read_end + FFMIN(buf + buf_size - read_end,
617 nb_desired * FLAC_AVG_FRAME_SIZE);
618 }
619
620 if (!av_fifo_space(fpc->fifo_buf) &&
621 av_fifo_size(fpc->fifo_buf) / FLAC_AVG_FRAME_SIZE >
622 fpc->nb_headers_buffered * 20) {
623 /* There is less than one valid flac header buffered for 20 headers
624 * buffered. Therefore the fifo is most likely filled with invalid
625 * data and the input is not a flac file. */
626 goto handle_error;
627 }
628
629 /* Fill the buffer. */
630 if ( av_fifo_space(fpc->fifo_buf) < read_end - read_start
631 && av_fifo_realloc2(fpc->fifo_buf, (read_end - read_start) + 2*av_fifo_size(fpc->fifo_buf)) < 0) {
632 av_log(avctx, AV_LOG_ERROR,
633 "couldn't reallocate buffer of size %"PTRDIFF_SPECIFIER"\n",
634 (read_end - read_start) + av_fifo_size(fpc->fifo_buf));
635 goto handle_error;
636 }
637
638 if (buf && buf_size) {
639 av_fifo_generic_write(fpc->fifo_buf, (void*) read_start,
640 read_end - read_start, NULL);
641 } else {
642 int8_t pad[MAX_FRAME_HEADER_SIZE] = { 0 };
643 av_fifo_generic_write(fpc->fifo_buf, pad, sizeof(pad), NULL);
644 }
645
646 /* Tag headers and update sequences. */
647 start_offset = av_fifo_size(fpc->fifo_buf) -
648 ((read_end - read_start) + (MAX_FRAME_HEADER_SIZE - 1));
649 start_offset = FFMAX(0, start_offset);
650 nb_headers = find_new_headers(fpc, start_offset);
651
652 if (nb_headers < 0) {
653 av_log(avctx, AV_LOG_ERROR,
654 "find_new_headers couldn't allocate FLAC header\n");
655 goto handle_error;
656 }
657
658 fpc->nb_headers_buffered = nb_headers;
659 /* Wait till FLAC_MIN_HEADERS to output a valid frame. */
660 if (!fpc->end_padded && fpc->nb_headers_buffered < FLAC_MIN_HEADERS) {
661 if (buf && read_end < buf + buf_size) {
662 read_start = read_end;
663 continue;
664 } else {
665 goto handle_error;
666 }
667 }
668
669 /* If headers found, update the scores since we have longer chains. */
670 if (fpc->end_padded || fpc->nb_headers_found)
671 score_sequences(fpc);
672
673 /* restore the state pre-padding */
674 if (fpc->end_padded) {
675 int warp = fpc->fifo_buf->wptr - fpc->fifo_buf->buffer < MAX_FRAME_HEADER_SIZE;
676 /* HACK: drain the tail of the fifo */
677 fpc->fifo_buf->wptr -= MAX_FRAME_HEADER_SIZE;
678 fpc->fifo_buf->wndx -= MAX_FRAME_HEADER_SIZE;
679 if (warp) {
680 fpc->fifo_buf->wptr += fpc->fifo_buf->end -
681 fpc->fifo_buf->buffer;
682 }
683 buf_size = 0;
684 read_start = read_end = NULL;
685 }
686 }
687
688 for (curr = fpc->headers; curr; curr = curr->next) {
689 if (curr->max_score > 0 &&
690 (!fpc->best_header || curr->max_score > fpc->best_header->max_score)) {
691 fpc->best_header = curr;
692 }
693 }
694
695 if (fpc->best_header) {
696 fpc->best_header_valid = 1;
697 if (fpc->best_header->offset > 0) {
698 /* Output a junk frame. */
699 av_log(avctx, AV_LOG_DEBUG, "Junk frame till offset %i\n",
700 fpc->best_header->offset);
701
702 /* Set duration to 0. It is unknown or invalid in a junk frame. */
703 s->duration = 0;
704 *poutbuf_size = fpc->best_header->offset;
705 *poutbuf = flac_fifo_read_wrap(fpc, 0, *poutbuf_size,
706 &fpc->wrap_buf,
707 &fpc->wrap_buf_allocated_size);
708 return buf_size ? (read_end - buf) : (fpc->best_header->offset -
709 av_fifo_size(fpc->fifo_buf));
710 }
711 if (!buf_size)
712 return get_best_header(fpc, poutbuf, poutbuf_size);
713 }
714
715handle_error:
716 *poutbuf = NULL;
717 *poutbuf_size = 0;
718 return buf_size ? read_end - buf : 0;
719}
720
721static av_cold int flac_parse_init(AVCodecParserContext *c)
722{
723 FLACParseContext *fpc = c->priv_data;
724 fpc->pc = c;
725 /* There will generally be FLAC_MIN_HEADERS buffered in the fifo before
726 it drains. This is allocated early to avoid slow reallocation. */
727 fpc->fifo_buf = av_fifo_alloc_array(FLAC_MIN_HEADERS + 3, FLAC_AVG_FRAME_SIZE);
728 if (!fpc->fifo_buf) {
729 av_log(fpc->avctx, AV_LOG_ERROR,
730 "couldn't allocate fifo_buf\n");
731 return AVERROR(ENOMEM);
732 }
733 return 0;
734}
735
736static void flac_parse_close(AVCodecParserContext *c)
737{
738 FLACParseContext *fpc = c->priv_data;
739 FLACHeaderMarker *curr = fpc->headers, *temp;
740
741 while (curr) {
742 temp = curr->next;
743 av_freep(&curr->link_penalty);
744 av_free(curr);
745 curr = temp;
746 }
747 av_fifo_freep(&fpc->fifo_buf);
748 av_freep(&fpc->wrap_buf);
749}
750
751AVCodecParser ff_flac_parser = {
752 .codec_ids = { AV_CODEC_ID_FLAC },
753 .priv_data_size = sizeof(FLACParseContext),
754 .parser_init = flac_parse_init,
755 .parser_parse = flac_parse,
756 .parser_close = flac_parse_close,
757};
758
generated by cgit at 2024-05-17 20:22:43 (GMT)