3 * Copyright (c) 2010 Michael Chinen
5 * This file is part of FFmpeg.
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.
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.
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
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.
35 #include "libavutil/attributes.h"
36 #include "libavutil/crc.h"
37 #include "libavutil/fifo.h"
38 #include "bytestream.h"
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
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
56 /** largest possible size of flac header */
57 #define MAX_FRAME_HEADER_SIZE 16
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
64 int max_score; /**< maximum score found after checking each child that
66 FLACFrameInfo fi; /**< decoded frame header info */
67 struct FLACHeaderMarker *next; /**< next CRC-8 verified header that
68 immediately follows this one in
70 struct FLACHeaderMarker *best_child; /**< following frame header with
71 which this frame has the best
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
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
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 */
95 static int frame_header_is_valid(AVCodecContext *avctx, const uint8_t *buf,
99 init_get_bits(&gb, buf, MAX_FRAME_HEADER_SIZE * 8);
100 return !ff_flac_decode_frame_header(avctx, &gb, fi, 127);
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
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.
116 static uint8_t *flac_fifo_read_wrap(FLACParseContext *fpc, int offset, int len,
117 uint8_t **wrap_buf, int *allocated_size)
119 AVFifoBuffer *f = fpc->fifo_buf;
120 uint8_t *start = f->rptr + offset;
124 start -= f->end - f->buffer;
125 if (f->end - start >= len)
128 tmp_buf = av_fast_realloc(*wrap_buf, allocated_size, len);
131 av_log(fpc->avctx, AV_LOG_ERROR,
132 "couldn't reallocate wrap buffer of size %d", len);
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
142 start += seg_len - (f->end - f->buffer);
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.
156 static uint8_t *flac_fifo_read(FLACParseContext *fpc, int offset, int *len)
158 AVFifoBuffer *f = fpc->fifo_buf;
159 uint8_t *start = f->rptr + offset;
162 start -= f->end - f->buffer;
163 *len = FFMIN(*len, f->end - start);
167 static int find_headers_search_validate(FLACParseContext *fpc, int offset)
172 header_buf = flac_fifo_read_wrap(fpc, offset,
173 MAX_FRAME_HEADER_SIZE,
175 &fpc->wrap_buf_allocated_size);
176 if (frame_header_is_valid(fpc->avctx, header_buf, &fi)) {
177 FLACHeaderMarker **end_handle = &fpc->headers;
181 while (*end_handle) {
182 end_handle = &(*end_handle)->next;
186 *end_handle = av_mallocz(sizeof(**end_handle));
188 av_log(fpc->avctx, AV_LOG_ERROR,
189 "couldn't allocate FLACHeaderMarker\n");
190 return AVERROR(ENOMEM);
192 (*end_handle)->fi = fi;
193 (*end_handle)->offset = offset;
195 for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++)
196 (*end_handle)->link_penalty[i] = FLAC_HEADER_NOT_PENALIZED_YET;
198 fpc->nb_headers_found++;
204 static int find_headers_search(FLACParseContext *fpc, uint8_t *buf,
205 int buf_size, int search_start)
207 int size = 0, mod_offset = (buf_size - 1) % 4, i, j;
210 for (i = 0; i < mod_offset; i++) {
211 if ((AV_RB16(buf + i) & 0xFFFE) == 0xFFF8)
212 size = find_headers_search_validate(fpc, search_start + i);
215 for (; i < buf_size - 1; i += 4) {
216 x = AV_RN32(buf + i);
217 if (((x & ~(x + 0x01010101)) & 0x80808080)) {
218 for (j = 0; j < 4; j++) {
219 if ((AV_RB16(buf + i + j) & 0xFFFE) == 0xFFF8)
220 size = find_headers_search_validate(fpc, search_start + i + j);
227 static int find_new_headers(FLACParseContext *fpc, int search_start)
229 FLACHeaderMarker *end;
230 int search_end, size = 0, read_len, temp;
232 fpc->nb_headers_found = 0;
234 /* Search for a new header of at most 16 bytes. */
235 search_end = av_fifo_size(fpc->fifo_buf) - (MAX_FRAME_HEADER_SIZE - 1);
236 read_len = search_end - search_start + 1;
237 buf = flac_fifo_read(fpc, search_start, &read_len);
238 size = find_headers_search(fpc, buf, read_len, search_start);
239 search_start += read_len - 1;
241 /* If fifo end was hit do the wrap around. */
242 if (search_start != search_end) {
245 wrap[0] = buf[read_len - 1];
246 /* search_start + 1 is the post-wrap offset in the fifo. */
247 read_len = search_end - (search_start + 1) + 1;
249 buf = flac_fifo_read(fpc, search_start + 1, &read_len);
252 if ((AV_RB16(wrap) & 0xFFFE) == 0xFFF8) {
253 temp = find_headers_search_validate(fpc, search_start);
254 size = FFMAX(size, temp);
258 /* Continue to do the last half of the wrap. */
259 temp = find_headers_search(fpc, buf, read_len, search_start);
260 size = FFMAX(size, temp);
261 search_start += read_len - 1;
264 /* Return the size even if no new headers were found. */
265 if (!size && fpc->headers)
266 for (end = fpc->headers; end; end = end->next)
271 static int check_header_fi_mismatch(FLACParseContext *fpc,
272 FLACFrameInfo *header_fi,
273 FLACFrameInfo *child_fi,
274 int log_level_offset)
277 if (child_fi->samplerate != header_fi->samplerate) {
278 deduction += FLAC_HEADER_CHANGED_PENALTY;
279 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
280 "sample rate change detected in adjacent frames\n");
282 if (child_fi->bps != header_fi->bps) {
283 deduction += FLAC_HEADER_CHANGED_PENALTY;
284 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
285 "bits per sample change detected in adjacent frames\n");
287 if (child_fi->is_var_size != header_fi->is_var_size) {
288 /* Changing blocking strategy not allowed per the spec */
289 deduction += FLAC_HEADER_BASE_SCORE;
290 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
291 "blocking strategy change detected in adjacent frames\n");
293 if (child_fi->channels != header_fi->channels) {
294 deduction += FLAC_HEADER_CHANGED_PENALTY;
295 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
296 "number of channels change detected in adjacent frames\n");
301 static int check_header_mismatch(FLACParseContext *fpc,
302 FLACHeaderMarker *header,
303 FLACHeaderMarker *child,
304 int log_level_offset)
306 FLACFrameInfo *header_fi = &header->fi, *child_fi = &child->fi;
307 int deduction, deduction_expected = 0, i;
308 deduction = check_header_fi_mismatch(fpc, header_fi, child_fi,
310 /* Check sample and frame numbers. */
311 if ((child_fi->frame_or_sample_num - header_fi->frame_or_sample_num
312 != header_fi->blocksize) &&
313 (child_fi->frame_or_sample_num
314 != header_fi->frame_or_sample_num + 1)) {
315 FLACHeaderMarker *curr;
316 int64_t expected_frame_num, expected_sample_num;
317 /* If there are frames in the middle we expect this deduction,
318 as they are probably valid and this one follows it */
320 expected_frame_num = expected_sample_num = header_fi->frame_or_sample_num;
322 while (curr != child) {
323 /* Ignore frames that failed all crc checks */
324 for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++) {
325 if (curr->link_penalty[i] < FLAC_HEADER_CRC_FAIL_PENALTY) {
326 expected_frame_num++;
327 expected_sample_num += curr->fi.blocksize;
334 if (expected_frame_num == child_fi->frame_or_sample_num ||
335 expected_sample_num == child_fi->frame_or_sample_num)
336 deduction_expected = deduction ? 0 : 1;
338 deduction += FLAC_HEADER_CHANGED_PENALTY;
339 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
340 "sample/frame number mismatch in adjacent frames\n");
343 /* If we have suspicious headers, check the CRC between them */
344 if (deduction && !deduction_expected) {
345 FLACHeaderMarker *curr;
349 int inverted_test = 0;
351 /* Since CRC is expensive only do it if we haven't yet.
352 This assumes a CRC penalty is greater than all other check penalties */
354 for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS && curr != child; i++)
357 if (header->link_penalty[i] < FLAC_HEADER_CRC_FAIL_PENALTY ||
358 header->link_penalty[i] == FLAC_HEADER_NOT_PENALIZED_YET) {
359 FLACHeaderMarker *start, *end;
361 /* Although overlapping chains are scored, the crc should never
362 have to be computed twice for a single byte. */
366 header->link_penalty[i - 1] >= FLAC_HEADER_CRC_FAIL_PENALTY) {
367 while (start->next != child)
371 header->next->link_penalty[i-1] >=
372 FLAC_HEADER_CRC_FAIL_PENALTY ) {
377 read_len = end->offset - start->offset;
378 buf = flac_fifo_read(fpc, start->offset, &read_len);
379 crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf, read_len);
380 read_len = (end->offset - start->offset) - read_len;
383 buf = flac_fifo_read(fpc, end->offset - read_len, &read_len);
384 crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), crc, buf, read_len);
388 if (!crc ^ !inverted_test) {
389 deduction += FLAC_HEADER_CRC_FAIL_PENALTY;
390 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
391 "crc check failed from offset %i (frame %"PRId64") to %i (frame %"PRId64")\n",
392 header->offset, header_fi->frame_or_sample_num,
393 child->offset, child_fi->frame_or_sample_num);
402 * Give FLAC_HEADER_BASE_SCORE points to a frame for existing.
403 * If it has children, (subsequent frames of which the preceding CRC footer
404 * validates against this one,) then take the maximum score of the children,
405 * with a penalty of FLAC_HEADER_CHANGED_PENALTY applied for each change to
406 * bps, sample rate, channels, but not decorrelation mode, or blocksize,
407 * because it can change often.
409 static int score_header(FLACParseContext *fpc, FLACHeaderMarker *header)
411 FLACHeaderMarker *child;
414 int base_score = FLAC_HEADER_BASE_SCORE;
415 if (header->max_score != FLAC_HEADER_NOT_SCORED_YET)
416 return header->max_score;
418 /* Modify the base score with changes from the last output header */
419 if (fpc->last_fi_valid) {
420 /* Silence the log since this will be repeated if selected */
421 base_score -= check_header_fi_mismatch(fpc, &fpc->last_fi, &header->fi,
425 header->max_score = base_score;
427 /* Check and compute the children's scores. */
428 child = header->next;
429 for (dist = 0; dist < FLAC_MAX_SEQUENTIAL_HEADERS && child; dist++) {
430 /* Look at the child's frame header info and penalize suspicious
431 changes between the headers. */
432 if (header->link_penalty[dist] == FLAC_HEADER_NOT_PENALIZED_YET) {
433 header->link_penalty[dist] = check_header_mismatch(fpc, header,
434 child, AV_LOG_DEBUG);
436 child_score = score_header(fpc, child) - header->link_penalty[dist];
438 if (FLAC_HEADER_BASE_SCORE + child_score > header->max_score) {
439 /* Keep the child because the frame scoring is dynamic. */
440 header->best_child = child;
441 header->max_score = base_score + child_score;
446 return header->max_score;
449 static void score_sequences(FLACParseContext *fpc)
451 FLACHeaderMarker *curr;
452 int best_score = 0;//FLAC_HEADER_NOT_SCORED_YET;
453 /* First pass to clear all old scores. */
454 for (curr = fpc->headers; curr; curr = curr->next)
455 curr->max_score = FLAC_HEADER_NOT_SCORED_YET;
457 /* Do a second pass to score them all. */
458 for (curr = fpc->headers; curr; curr = curr->next) {
459 if (score_header(fpc, curr) > best_score) {
460 fpc->best_header = curr;
461 best_score = curr->max_score;
466 static int get_best_header(FLACParseContext *fpc, const uint8_t **poutbuf,
469 FLACHeaderMarker *header = fpc->best_header;
470 FLACHeaderMarker *child = header->best_child;
472 *poutbuf_size = av_fifo_size(fpc->fifo_buf) - header->offset;
474 *poutbuf_size = child->offset - header->offset;
476 /* If the child has suspicious changes, log them */
477 check_header_mismatch(fpc, header, child, 0);
480 if (header->fi.channels != fpc->avctx->channels ||
481 !fpc->avctx->channel_layout) {
482 fpc->avctx->channels = header->fi.channels;
483 ff_flac_set_channel_layout(fpc->avctx);
485 fpc->avctx->sample_rate = header->fi.samplerate;
486 fpc->pc->duration = header->fi.blocksize;
487 *poutbuf = flac_fifo_read_wrap(fpc, header->offset, *poutbuf_size,
489 &fpc->wrap_buf_allocated_size);
492 if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS) {
493 if (header->fi.is_var_size)
494 fpc->pc->pts = header->fi.frame_or_sample_num;
495 else if (header->best_child)
496 fpc->pc->pts = header->fi.frame_or_sample_num * header->fi.blocksize;
499 fpc->best_header_valid = 0;
500 fpc->last_fi_valid = 1;
501 fpc->last_fi = header->fi;
503 /* Return the negative overread index so the client can compute pos.
504 This should be the amount overread to the beginning of the child */
506 return child->offset - av_fifo_size(fpc->fifo_buf);
510 static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
511 const uint8_t **poutbuf, int *poutbuf_size,
512 const uint8_t *buf, int buf_size)
514 FLACParseContext *fpc = s->priv_data;
515 FLACHeaderMarker *curr;
517 const uint8_t *read_end = buf;
518 const uint8_t *read_start = buf;
520 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
522 if (frame_header_is_valid(avctx, buf, &fi)) {
523 s->duration = fi.blocksize;
524 if (!avctx->sample_rate)
525 avctx->sample_rate = fi.samplerate;
526 if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS) {
527 fpc->pc->pts = fi.frame_or_sample_num;
529 fpc->pc->pts *= fi.blocksize;
533 *poutbuf_size = buf_size;
538 if (fpc->best_header_valid)
539 return get_best_header(fpc, poutbuf, poutbuf_size);
541 /* If a best_header was found last call remove it with the buffer data. */
542 if (fpc->best_header && fpc->best_header->best_child) {
543 FLACHeaderMarker *temp;
544 FLACHeaderMarker *best_child = fpc->best_header->best_child;
546 /* Remove headers in list until the end of the best_header. */
547 for (curr = fpc->headers; curr != best_child; curr = temp) {
548 if (curr != fpc->best_header) {
549 av_log(avctx, AV_LOG_DEBUG,
550 "dropping low score %i frame header from offset %i to %i\n",
551 curr->max_score, curr->offset, curr->next->offset);
555 fpc->nb_headers_buffered--;
557 /* Release returned data from ring buffer. */
558 av_fifo_drain(fpc->fifo_buf, best_child->offset);
560 /* Fix the offset for the headers remaining to match the new buffer. */
561 for (curr = best_child->next; curr; curr = curr->next)
562 curr->offset -= best_child->offset;
564 best_child->offset = 0;
565 fpc->headers = best_child;
566 if (fpc->nb_headers_buffered >= FLAC_MIN_HEADERS) {
567 fpc->best_header = best_child;
568 return get_best_header(fpc, poutbuf, poutbuf_size);
570 fpc->best_header = NULL;
571 } else if (fpc->best_header) {
572 /* No end frame no need to delete the buffer; probably eof */
573 FLACHeaderMarker *temp;
575 for (curr = fpc->headers; curr != fpc->best_header; curr = temp) {
578 fpc->nb_headers_buffered--;
580 fpc->headers = fpc->best_header->next;
581 av_freep(&fpc->best_header);
582 fpc->nb_headers_buffered--;
585 /* Find and score new headers. */
586 /* buf_size is zero when flushing, so check for this since we do */
587 /* not want to try to read more input once we have found the end. */
588 /* Also note that buf can't be NULL. */
589 while ((buf_size && read_end < buf + buf_size &&
590 fpc->nb_headers_buffered < FLAC_MIN_HEADERS)
591 || (!buf_size && !fpc->end_padded)) {
594 /* Pad the end once if EOF, to check the final region for headers. */
597 read_end = read_start + MAX_FRAME_HEADER_SIZE;
599 /* The maximum read size is the upper-bound of what the parser
600 needs to have the required number of frames buffered */
601 int nb_desired = FLAC_MIN_HEADERS - fpc->nb_headers_buffered + 1;
602 read_end = read_end + FFMIN(buf + buf_size - read_end,
603 nb_desired * FLAC_AVG_FRAME_SIZE);
606 if (!av_fifo_space(fpc->fifo_buf) &&
607 av_fifo_size(fpc->fifo_buf) / FLAC_AVG_FRAME_SIZE >
608 fpc->nb_headers_buffered * 20) {
609 /* There is less than one valid flac header buffered for 20 headers
610 * buffered. Therefore the fifo is most likely filled with invalid
611 * data and the input is not a flac file. */
615 /* Fill the buffer. */
616 if ( av_fifo_space(fpc->fifo_buf) < read_end - read_start
617 && av_fifo_realloc2(fpc->fifo_buf, (read_end - read_start) + 2*av_fifo_size(fpc->fifo_buf)) < 0) {
618 av_log(avctx, AV_LOG_ERROR,
619 "couldn't reallocate buffer of size %"PTRDIFF_SPECIFIER"\n",
620 (read_end - read_start) + av_fifo_size(fpc->fifo_buf));
625 av_fifo_generic_write(fpc->fifo_buf, (void*) read_start,
626 read_end - read_start, NULL);
628 int8_t pad[MAX_FRAME_HEADER_SIZE] = { 0 };
629 av_fifo_generic_write(fpc->fifo_buf, pad, sizeof(pad), NULL);
632 /* Tag headers and update sequences. */
633 start_offset = av_fifo_size(fpc->fifo_buf) -
634 ((read_end - read_start) + (MAX_FRAME_HEADER_SIZE - 1));
635 start_offset = FFMAX(0, start_offset);
636 nb_headers = find_new_headers(fpc, start_offset);
638 if (nb_headers < 0) {
639 av_log(avctx, AV_LOG_ERROR,
640 "find_new_headers couldn't allocate FLAC header\n");
644 fpc->nb_headers_buffered = nb_headers;
645 /* Wait till FLAC_MIN_HEADERS to output a valid frame. */
646 if (!fpc->end_padded && fpc->nb_headers_buffered < FLAC_MIN_HEADERS) {
647 if (read_end < buf + buf_size) {
648 read_start = read_end;
655 /* If headers found, update the scores since we have longer chains. */
656 if (fpc->end_padded || fpc->nb_headers_found)
657 score_sequences(fpc);
659 /* restore the state pre-padding */
660 if (fpc->end_padded) {
661 int warp = fpc->fifo_buf->wptr - fpc->fifo_buf->buffer < MAX_FRAME_HEADER_SIZE;
662 /* HACK: drain the tail of the fifo */
663 fpc->fifo_buf->wptr -= MAX_FRAME_HEADER_SIZE;
664 fpc->fifo_buf->wndx -= MAX_FRAME_HEADER_SIZE;
666 fpc->fifo_buf->wptr += fpc->fifo_buf->end -
667 fpc->fifo_buf->buffer;
669 read_start = read_end = NULL;
673 for (curr = fpc->headers; curr; curr = curr->next) {
674 if (!fpc->best_header || curr->max_score > fpc->best_header->max_score) {
675 fpc->best_header = curr;
679 if (fpc->best_header && fpc->best_header->max_score <= 0) {
680 // Only accept a bad header if there is no other option to continue
681 if (!buf_size || read_end != buf || fpc->nb_headers_buffered < FLAC_MIN_HEADERS)
682 fpc->best_header = NULL;
685 if (fpc->best_header) {
686 fpc->best_header_valid = 1;
687 if (fpc->best_header->offset > 0) {
688 /* Output a junk frame. */
689 av_log(avctx, AV_LOG_DEBUG, "Junk frame till offset %i\n",
690 fpc->best_header->offset);
692 /* Set duration to 0. It is unknown or invalid in a junk frame. */
694 *poutbuf_size = fpc->best_header->offset;
695 *poutbuf = flac_fifo_read_wrap(fpc, 0, *poutbuf_size,
697 &fpc->wrap_buf_allocated_size);
698 return buf_size ? (read_end - buf) : (fpc->best_header->offset -
699 av_fifo_size(fpc->fifo_buf));
702 return get_best_header(fpc, poutbuf, poutbuf_size);
708 return buf_size ? read_end - buf : 0;
711 static av_cold int flac_parse_init(AVCodecParserContext *c)
713 FLACParseContext *fpc = c->priv_data;
715 /* There will generally be FLAC_MIN_HEADERS buffered in the fifo before
716 it drains. This is allocated early to avoid slow reallocation. */
717 fpc->fifo_buf = av_fifo_alloc_array(FLAC_MIN_HEADERS + 3, FLAC_AVG_FRAME_SIZE);
718 if (!fpc->fifo_buf) {
719 av_log(fpc->avctx, AV_LOG_ERROR,
720 "couldn't allocate fifo_buf\n");
721 return AVERROR(ENOMEM);
726 static void flac_parse_close(AVCodecParserContext *c)
728 FLACParseContext *fpc = c->priv_data;
729 FLACHeaderMarker *curr = fpc->headers, *temp;
737 av_fifo_freep(&fpc->fifo_buf);
738 av_freep(&fpc->wrap_buf);
741 AVCodecParser ff_flac_parser = {
742 .codec_ids = { AV_CODEC_ID_FLAC },
743 .priv_data_size = sizeof(FLACParseContext),
744 .parser_init = flac_parse_init,
745 .parser_parse = flac_parse,
746 .parser_close = flac_parse_close,