FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/flac_parser.c
Date: 2022-01-23 21:51:25
Exec Total Coverage
Lines: 336 413 81.4%
Branches: 187 264 70.8%

Line Branch Exec Source
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 "bytestream.h"
38 #include "parser.h"
39 #include "flac.h"
40
41 /** maximum number of adjacent headers that compare CRCs against each other */
42 #define FLAC_MAX_SEQUENTIAL_HEADERS 4
43 /** minimum number of headers buffered and checked before returning frames */
44 #define FLAC_MIN_HEADERS 10
45 /** estimate for average size of a FLAC frame */
46 #define FLAC_AVG_FRAME_SIZE 8192
47
48 /** scoring settings for score_header */
49 #define FLAC_HEADER_BASE_SCORE 10
50 #define FLAC_HEADER_CHANGED_PENALTY 7
51 #define FLAC_HEADER_CRC_FAIL_PENALTY 50
52 #define FLAC_HEADER_NOT_PENALIZED_YET 100000
53 #define FLAC_HEADER_NOT_SCORED_YET -100000
54
55 /** largest possible size of flac header */
56 #define MAX_FRAME_HEADER_SIZE 16
57 #define MAX_FRAME_VERIFY_SIZE (MAX_FRAME_HEADER_SIZE + 1)
58
59 typedef struct FifoBuffer {
60 uint8_t *buffer;
61 uint8_t *end;
62 uint8_t *rptr;
63 uint8_t *wptr;
64 int empty;
65 } FifoBuffer;
66
67 typedef struct FLACHeaderMarker {
68 int offset; /**< byte offset from start of FLACParseContext->buffer */
69 int link_penalty[FLAC_MAX_SEQUENTIAL_HEADERS]; /**< array of local scores
70 between this header and the one at a distance equal
71 array position */
72 int max_score; /**< maximum score found after checking each child that
73 has a valid CRC */
74 FLACFrameInfo fi; /**< decoded frame header info */
75 struct FLACHeaderMarker *next; /**< next CRC-8 verified header that
76 immediately follows this one in
77 the bytestream */
78 struct FLACHeaderMarker *best_child; /**< following frame header with
79 which this frame has the best
80 score with */
81 } FLACHeaderMarker;
82
83 typedef struct FLACParseContext {
84 AVCodecParserContext *pc; /**< parent context */
85 AVCodecContext *avctx; /**< codec context pointer for logging */
86 FLACHeaderMarker *headers; /**< linked-list that starts at the first
87 CRC-8 verified header within buffer */
88 FLACHeaderMarker *best_header; /**< highest scoring header within buffer */
89 int nb_headers_found; /**< number of headers found in the last
90 flac_parse() call */
91 int nb_headers_buffered; /**< number of headers that are buffered */
92 int best_header_valid; /**< flag set when the parser returns junk;
93 if set return best_header next time */
94 FifoBuffer fifo_buf; /**< buffer to store all data until headers
95 can be verified */
96 int end_padded; /**< specifies if fifo_buf's end is padded */
97 uint8_t *wrap_buf; /**< general fifo read buffer when wrapped */
98 int wrap_buf_allocated_size; /**< actual allocated size of the buffer */
99 FLACFrameInfo last_fi; /**< last decoded frame header info */
100 int last_fi_valid; /**< set if last_fi is valid */
101 } FLACParseContext;
102
103 4724 static int frame_header_is_valid(AVCodecContext *avctx, const uint8_t *buf,
104 FLACFrameInfo *fi)
105 {
106 GetBitContext gb;
107 uint8_t subframe_type;
108
109 // header plus one byte from first subframe
110 4724 init_get_bits(&gb, buf, MAX_FRAME_VERIFY_SIZE * 8);
111
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4724 if (ff_flac_decode_frame_header(avctx, &gb, fi, 127)) {
112 764 return 0;
113 }
114 // subframe zero bit
115
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3960 if (get_bits1(&gb) != 0) {
116 return 0;
117 }
118 // subframe type
119 // 000000 : SUBFRAME_CONSTANT
120 // 000001 : SUBFRAME_VERBATIM
121 // 00001x : reserved
122 // 0001xx : reserved
123 // 001xxx : if(xxx <= 4) SUBFRAME_FIXED, xxx=order ; else reserved
124 // 01xxxx : reserved
125 // 1xxxxx : SUBFRAME_LPC, xxxxx=order-1
126 3960 subframe_type = get_bits(&gb, 6);
127
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5847 if (!(subframe_type == 0 ||
128
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3837 subframe_type == 1 ||
129
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3837 ((subframe_type >= 8) && (subframe_type <= 12)) ||
130 (subframe_type >= 32))) {
131 return 0;
132 }
133
134 3960 return 1;
135 }
136
137 123403 static size_t flac_fifo_size(const FifoBuffer *f)
138 {
139
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123403 if (f->wptr <= f->rptr && !f->empty)
140 55828 return (f->wptr - f->buffer) + (f->end - f->rptr);
141 67575 return f->wptr - f->rptr;
142 }
143
144 59106 static size_t flac_fifo_space(const FifoBuffer *f)
145 {
146 59106 return f->end - f->buffer - flac_fifo_size(f);
147 }
148
149 /**
150 * Non-destructive fast fifo pointer fetching
151 * Returns a pointer from the specified offset.
152 * If possible the pointer points within the fifo buffer.
153 * Otherwise (if it would cause a wrap around,) a pointer to a user-specified
154 * buffer is used.
155 * The pointer can be NULL. In any case it will be reallocated to hold the size.
156 * If the returned pointer will be used after subsequent calls to flac_fifo_read_wrap
157 * then the subsequent calls should pass in a different wrap_buf so as to not
158 * overwrite the contents of the previous wrap_buf.
159 * This function is based on av_fifo_generic_read, which is why there is a comment
160 * about a memory barrier for SMP.
161 */
162 7327 static uint8_t *flac_fifo_read_wrap(FLACParseContext *fpc, int offset, int len,
163 uint8_t **wrap_buf, int *allocated_size)
164 {
165 7327 FifoBuffer *f = &fpc->fifo_buf;
166 7327 uint8_t *start = f->rptr + offset;
167 uint8_t *tmp_buf;
168
169
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7327 if (start >= f->end)
170 1350 start -= f->end - f->buffer;
171
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7327 if (f->end - start >= len)
172 7204 return start;
173
174 123 tmp_buf = av_fast_realloc(*wrap_buf, allocated_size, len);
175
176
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123 if (!tmp_buf) {
177 av_log(fpc->avctx, AV_LOG_ERROR,
178 "couldn't reallocate wrap buffer of size %d", len);
179 return NULL;
180 }
181 123 *wrap_buf = tmp_buf;
182 do {
183 246 int seg_len = FFMIN(f->end - start, len);
184 246 memcpy(tmp_buf, start, seg_len);
185 246 tmp_buf = (uint8_t*)tmp_buf + seg_len;
186 // memory barrier needed for SMP here in theory
187
188 246 start += seg_len - (f->end - f->buffer);
189 246 len -= seg_len;
190
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246 } while (len > 0);
191
192 123 return *wrap_buf;
193 }
194
195 /**
196 * Return a pointer in the fifo buffer where the offset starts at until
197 * the wrap point or end of request.
198 * len will contain the valid length of the returned buffer.
199 * A second call to flac_fifo_read (with new offset and len) should be called
200 * to get the post-wrap buf if the returned len is less than the requested.
201 **/
202 29691 static uint8_t *flac_fifo_read(FifoBuffer *f, int offset, int *len)
203 {
204 29691 uint8_t *start = f->rptr + offset;
205
206
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29691 if (start >= f->end)
207 13444 start -= f->end - f->buffer;
208 29691 *len = FFMIN(*len, f->end - start);
209 29691 return start;
210 }
211
212 23 static int flac_fifo_grow(FifoBuffer *f, size_t inc)
213 {
214 23 size_t size_old = f->end - f->buffer;
215 23 size_t offset_r = f->rptr - f->buffer;
216 23 size_t offset_w = f->wptr - f->buffer;
217 size_t size_new;
218
219 uint8_t *tmp;
220
221
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23 if (size_old > SIZE_MAX - inc)
222 return AVERROR(EINVAL);
223 23 size_new = size_old + inc;
224
225 23 tmp = av_realloc(f->buffer, size_new);
226
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23 if (!tmp)
227 return AVERROR(ENOMEM);
228
229 // move the data from the beginning of the ring buffer
230 // to the newly allocated space
231
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23 if (offset_w <= offset_r && !f->empty) {
232 16 const size_t copy = FFMIN(inc, offset_w);
233 16 memcpy(tmp + size_old, tmp, copy);
234
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16 if (copy < offset_w) {
235 memmove(tmp, tmp + copy, offset_w - copy);
236 offset_w -= copy;
237 } else
238 16 offset_w = size_old + copy;
239 }
240
241 23 f->buffer = tmp;
242 23 f->end = f->buffer + size_new;
243 23 f->rptr = f->buffer + offset_r;
244 23 f->wptr = f->buffer + offset_w;
245
246 23 return 0;
247 }
248
249 29553 static int flac_fifo_write(FifoBuffer *f, const uint8_t *src, size_t size)
250 {
251 uint8_t *wptr;
252
253
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29553 if (flac_fifo_space(f) < size) {
254
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23 int ret = flac_fifo_grow(f, FFMAX(flac_fifo_size(f), size));
255
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23 if (ret < 0)
256 return ret;
257 }
258
259
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29553 if (size)
260 29553 f->empty = 0;
261
262 29553 wptr = f->wptr;
263 do {
264 29687 size_t len = FFMIN(f->end - wptr, size);
265 29687 memcpy(wptr, src, len);
266 29687 src += len;
267 29687 wptr += len;
268
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29687 if (wptr >= f->end)
269 139 wptr = f->buffer;
270 29687 size -= len;
271
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29687 } while (size > 0);
272
273 29553 f->wptr = wptr;
274
275 29553 return 0;
276 }
277
278 2478 static void flac_fifo_drain(FifoBuffer *f, size_t size)
279 {
280 2478 size_t size_cur = flac_fifo_size(f);
281
282
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2478 av_assert0(size_cur >= size);
283
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2478 if (size_cur == size)
284 f->empty = 1;
285
286 2478 f->rptr += size;
287
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2478 if (f->rptr >= f->end)
288 123 f->rptr -= f->end - f->buffer;
289 2478 }
290
291 204 static int flac_fifo_alloc(FifoBuffer *f, size_t size)
292 {
293 204 memset(f, 0, sizeof(*f));
294
295 204 f->buffer = av_realloc(NULL, size);
296
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204 if (!f->buffer)
297 return AVERROR(ENOMEM);
298
299 204 f->wptr = f->buffer;
300 204 f->rptr = f->buffer;
301 204 f->end = f->buffer + size;
302
303 204 f->empty = 1;
304
305 204 return 0;
306 }
307
308 204 static void flac_fifo_free(FifoBuffer *f)
309 {
310 204 av_freep(&f->buffer);
311 204 memset(f, 0, sizeof(*f));
312 204 }
313
314 4601 static int find_headers_search_validate(FLACParseContext *fpc, int offset)
315 {
316 FLACFrameInfo fi;
317 uint8_t *header_buf;
318 4601 int size = 0;
319 4601 header_buf = flac_fifo_read_wrap(fpc, offset,
320 MAX_FRAME_VERIFY_SIZE + AV_INPUT_BUFFER_PADDING_SIZE,
321 &fpc->wrap_buf,
322 &fpc->wrap_buf_allocated_size);
323
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4601 if (frame_header_is_valid(fpc->avctx, header_buf, &fi)) {
324 3845 FLACHeaderMarker **end_handle = &fpc->headers;
325 int i;
326
327 3845 size = 0;
328
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31279 while (*end_handle) {
329 27434 end_handle = &(*end_handle)->next;
330 27434 size++;
331 }
332
333 3845 *end_handle = av_mallocz(sizeof(**end_handle));
334
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3845 if (!*end_handle) {
335 av_log(fpc->avctx, AV_LOG_ERROR,
336 "couldn't allocate FLACHeaderMarker\n");
337 return AVERROR(ENOMEM);
338 }
339 3845 (*end_handle)->fi = fi;
340 3845 (*end_handle)->offset = offset;
341
342
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19225 for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++)
343 15380 (*end_handle)->link_penalty[i] = FLAC_HEADER_NOT_PENALIZED_YET;
344
345 3845 fpc->nb_headers_found++;
346 3845 size++;
347 }
348 4601 return size;
349 }
350
351 29691 static int find_headers_search(FLACParseContext *fpc, uint8_t *buf,
352 int buf_size, int search_start)
353 {
354 29691 int size = 0, mod_offset = (buf_size - 1) % 4, i, j;
355 uint32_t x;
356
357
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30355 for (i = 0; i < mod_offset; i++) {
358
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664 if ((AV_RB16(buf + i) & 0xFFFE) == 0xFFF8) {
359 63 int ret = find_headers_search_validate(fpc, search_start + i);
360 63 size = FFMAX(size, ret);
361 }
362 }
363
364
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7575682 for (; i < buf_size - 1; i += 4) {
365 7545991 x = AV_RN32(buf + i);
366
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7545991 if (((x & ~(x + 0x01010101)) & 0x80808080)) {
367
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526245 for (j = 0; j < 4; j++) {
368
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420996 if ((AV_RB16(buf + i + j) & 0xFFFE) == 0xFFF8) {
369 4538 int ret = find_headers_search_validate(fpc, search_start + i + j);
370 4538 size = FFMAX(size, ret);
371 }
372 }
373 }
374 }
375 29691 return size;
376 }
377
378 29553 static int find_new_headers(FLACParseContext *fpc, int search_start)
379 {
380 FLACHeaderMarker *end;
381 29553 int search_end, size = 0, read_len, temp;
382 uint8_t *buf;
383 29553 fpc->nb_headers_found = 0;
384
385 /* Search for a new header of at most 16 bytes. */
386 29553 search_end = flac_fifo_size(&fpc->fifo_buf) - (MAX_FRAME_HEADER_SIZE - 1);
387 29553 read_len = search_end - search_start + 1;
388 29553 buf = flac_fifo_read(&fpc->fifo_buf, search_start, &read_len);
389 29553 size = find_headers_search(fpc, buf, read_len, search_start);
390 29553 search_start += read_len - 1;
391
392 /* If fifo end was hit do the wrap around. */
393
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29553 if (search_start != search_end) {
394 uint8_t wrap[2];
395
396 138 wrap[0] = buf[read_len - 1];
397 /* search_start + 1 is the post-wrap offset in the fifo. */
398 138 read_len = search_end - (search_start + 1) + 1;
399
400 138 buf = flac_fifo_read(&fpc->fifo_buf, search_start + 1, &read_len);
401 138 wrap[1] = buf[0];
402
403
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138 if ((AV_RB16(wrap) & 0xFFFE) == 0xFFF8) {
404 temp = find_headers_search_validate(fpc, search_start);
405 size = FFMAX(size, temp);
406 }
407 138 search_start++;
408
409 /* Continue to do the last half of the wrap. */
410 138 temp = find_headers_search(fpc, buf, read_len, search_start);
411 138 size = FFMAX(size, temp);
412 138 search_start += read_len - 1;
413 }
414
415 /* Return the size even if no new headers were found. */
416
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29553 if (!size && fpc->headers)
417
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251508 for (end = fpc->headers; end; end = end->next)
418 225504 size++;
419 29553 return size;
420 }
421
422 38714 static int check_header_fi_mismatch(FLACParseContext *fpc,
423 FLACFrameInfo *header_fi,
424 FLACFrameInfo *child_fi,
425 int log_level_offset)
426 {
427 38714 int deduction = 0;
428
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38714 if (child_fi->samplerate != header_fi->samplerate) {
429 deduction += FLAC_HEADER_CHANGED_PENALTY;
430 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
431 "sample rate change detected in adjacent frames\n");
432 }
433
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38714 if (child_fi->bps != header_fi->bps) {
434 deduction += FLAC_HEADER_CHANGED_PENALTY;
435 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
436 "bits per sample change detected in adjacent frames\n");
437 }
438
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38714 if (child_fi->is_var_size != header_fi->is_var_size) {
439 /* Changing blocking strategy not allowed per the spec */
440 deduction += FLAC_HEADER_BASE_SCORE;
441 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
442 "blocking strategy change detected in adjacent frames\n");
443 }
444
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38714 if (child_fi->channels != header_fi->channels) {
445 deduction += FLAC_HEADER_CHANGED_PENALTY;
446 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
447 "number of channels change detected in adjacent frames\n");
448 }
449 38714 return deduction;
450 }
451
452 16327 static int check_header_mismatch(FLACParseContext *fpc,
453 FLACHeaderMarker *header,
454 FLACHeaderMarker *child,
455 int log_level_offset)
456 {
457 16327 FLACFrameInfo *header_fi = &header->fi, *child_fi = &child->fi;
458 16327 int deduction, deduction_expected = 0, i;
459 16327 deduction = check_header_fi_mismatch(fpc, header_fi, child_fi,
460 log_level_offset);
461 /* Check sample and frame numbers. */
462 16327 if ((child_fi->frame_or_sample_num - header_fi->frame_or_sample_num
463
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16327 != header_fi->blocksize) &&
464 16327 (child_fi->frame_or_sample_num
465
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16327 != header_fi->frame_or_sample_num + 1)) {
466 FLACHeaderMarker *curr;
467 int64_t expected_frame_num, expected_sample_num;
468 /* If there are frames in the middle we expect this deduction,
469 as they are probably valid and this one follows it */
470
471 10065 expected_frame_num = expected_sample_num = header_fi->frame_or_sample_num;
472 10065 curr = header;
473
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39944 while (curr != child) {
474 /* Ignore frames that failed all crc checks */
475
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29879 for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++) {
476
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29879 if (curr->link_penalty[i] < FLAC_HEADER_CRC_FAIL_PENALTY) {
477 29879 expected_frame_num++;
478 29879 expected_sample_num += curr->fi.blocksize;
479 29879 break;
480 }
481 }
482 29879 curr = curr->next;
483 }
484
485
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10065 if (expected_frame_num == child_fi->frame_or_sample_num ||
486 expected_sample_num == child_fi->frame_or_sample_num)
487 10065 deduction_expected = deduction ? 0 : 1;
488
489 10065 deduction += FLAC_HEADER_CHANGED_PENALTY;
490 10065 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
491 "sample/frame number mismatch in adjacent frames\n");
492 }
493
494 /* If we have suspicious headers, check the CRC between them */
495
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16327 if (deduction && !deduction_expected) {
496 FLACHeaderMarker *curr;
497 int read_len;
498 uint8_t *buf;
499 uint32_t crc = 1;
500 int inverted_test = 0;
501
502 /* Since CRC is expensive only do it if we haven't yet.
503 This assumes a CRC penalty is greater than all other check penalties */
504 curr = header->next;
505 for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS && curr != child; i++)
506 curr = curr->next;
507
508 if (header->link_penalty[i] < FLAC_HEADER_CRC_FAIL_PENALTY ||
509 header->link_penalty[i] == FLAC_HEADER_NOT_PENALIZED_YET) {
510 FLACHeaderMarker *start, *end;
511
512 /* Although overlapping chains are scored, the crc should never
513 have to be computed twice for a single byte. */
514 start = header;
515 end = child;
516 if (i > 0 &&
517 header->link_penalty[i - 1] >= FLAC_HEADER_CRC_FAIL_PENALTY) {
518 while (start->next != child)
519 start = start->next;
520 inverted_test = 1;
521 } else if (i > 0 &&
522 header->next->link_penalty[i-1] >=
523 FLAC_HEADER_CRC_FAIL_PENALTY ) {
524 end = header->next;
525 inverted_test = 1;
526 }
527
528 read_len = end->offset - start->offset;
529 buf = flac_fifo_read(&fpc->fifo_buf, start->offset, &read_len);
530 crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf, read_len);
531 read_len = (end->offset - start->offset) - read_len;
532
533 if (read_len) {
534 buf = flac_fifo_read(&fpc->fifo_buf, end->offset - read_len, &read_len);
535 crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), crc, buf, read_len);
536 }
537 }
538
539 if (!crc ^ !inverted_test) {
540 deduction += FLAC_HEADER_CRC_FAIL_PENALTY;
541 av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset,
542 "crc check failed from offset %i (frame %"PRId64") to %i (frame %"PRId64")\n",
543 header->offset, header_fi->frame_or_sample_num,
544 child->offset, child_fi->frame_or_sample_num);
545 }
546 }
547 16327 return deduction;
548 }
549
550 /**
551 * Score a header.
552 *
553 * Give FLAC_HEADER_BASE_SCORE points to a frame for existing.
554 * If it has children, (subsequent frames of which the preceding CRC footer
555 * validates against this one,) then take the maximum score of the children,
556 * with a penalty of FLAC_HEADER_CHANGED_PENALTY applied for each change to
557 * bps, sample rate, channels, but not decorrelation mode, or blocksize,
558 * because it can change often.
559 **/
560 95881 static int score_header(FLACParseContext *fpc, FLACHeaderMarker *header)
561 {
562 FLACHeaderMarker *child;
563 95881 int dist = 0;
564 int child_score;
565 95881 int base_score = FLAC_HEADER_BASE_SCORE;
566
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95881 if (header->max_score != FLAC_HEADER_NOT_SCORED_YET)
567 71903 return header->max_score;
568
569 /* Modify the base score with changes from the last output header */
570
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23978 if (fpc->last_fi_valid) {
571 /* Silence the log since this will be repeated if selected */
572 22387 base_score -= check_header_fi_mismatch(fpc, &fpc->last_fi, &header->fi,
573 AV_LOG_DEBUG);
574 }
575
576 23978 header->max_score = base_score;
577
578 /* Check and compute the children's scores. */
579 23978 child = header->next;
580
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95881 for (dist = 0; dist < FLAC_MAX_SEQUENTIAL_HEADERS && child; dist++) {
581 /* Look at the child's frame header info and penalize suspicious
582 changes between the headers. */
583
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71903 if (header->link_penalty[dist] == FLAC_HEADER_NOT_PENALIZED_YET) {
584 13741 header->link_penalty[dist] = check_header_mismatch(fpc, header,
585 child, AV_LOG_DEBUG);
586 }
587 71903 child_score = score_header(fpc, child) - header->link_penalty[dist];
588
589
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71903 if (FLAC_HEADER_BASE_SCORE + child_score > header->max_score) {
590 /* Keep the child because the frame scoring is dynamic. */
591 21572 header->best_child = child;
592 21572 header->max_score = base_score + child_score;
593 }
594 71903 child = child->next;
595 }
596
597 23978 return header->max_score;
598 }
599
600 2406 static void score_sequences(FLACParseContext *fpc)
601 {
602 FLACHeaderMarker *curr;
603 2406 int best_score = 0;//FLAC_HEADER_NOT_SCORED_YET;
604 /* First pass to clear all old scores. */
605
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26384 for (curr = fpc->headers; curr; curr = curr->next)
606 23978 curr->max_score = FLAC_HEADER_NOT_SCORED_YET;
607
608 /* Do a second pass to score them all. */
609
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26384 for (curr = fpc->headers; curr; curr = curr->next) {
610
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23978 if (score_header(fpc, curr) > best_score) {
611 2406 fpc->best_header = curr;
612 2406 best_score = curr->max_score;
613 }
614 }
615 2406 }
616
617 2620 static int get_best_header(FLACParseContext *fpc, const uint8_t **poutbuf,
618 int *poutbuf_size)
619 {
620 2620 FLACHeaderMarker *header = fpc->best_header;
621 2620 FLACHeaderMarker *child = header->best_child;
622
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2620 if (!child) {
623 34 *poutbuf_size = flac_fifo_size(&fpc->fifo_buf) - header->offset;
624 } else {
625 2586 *poutbuf_size = child->offset - header->offset;
626
627 /* If the child has suspicious changes, log them */
628 2586 check_header_mismatch(fpc, header, child, 0);
629 }
630
631
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2620 if (header->fi.channels != fpc->avctx->channels ||
632
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2620 !fpc->avctx->channel_layout) {
633 fpc->avctx->channels = header->fi.channels;
634 ff_flac_set_channel_layout(fpc->avctx);
635 }
636 2620 fpc->avctx->sample_rate = header->fi.samplerate;
637 2620 fpc->pc->duration = header->fi.blocksize;
638 2620 *poutbuf = flac_fifo_read_wrap(fpc, header->offset, *poutbuf_size,
639 &fpc->wrap_buf,
640 &fpc->wrap_buf_allocated_size);
641
642
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2620 if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS) {
643
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2620 if (header->fi.is_var_size)
644 fpc->pc->pts = header->fi.frame_or_sample_num;
645
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2620 else if (header->best_child)
646 2586 fpc->pc->pts = header->fi.frame_or_sample_num * header->fi.blocksize;
647 }
648
649 2620 fpc->best_header_valid = 0;
650 2620 fpc->last_fi_valid = 1;
651 2620 fpc->last_fi = header->fi;
652
653 /* Return the negative overread index so the client can compute pos.
654 This should be the amount overread to the beginning of the child */
655
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2620 if (child)
656 2586 return child->offset - flac_fifo_size(&fpc->fifo_buf);
657 34 return 0;
658 }
659
660 32302 static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx,
661 const uint8_t **poutbuf, int *poutbuf_size,
662 const uint8_t *buf, int buf_size)
663 {
664 32302 FLACParseContext *fpc = s->priv_data;
665 FLACHeaderMarker *curr;
666 int nb_headers;
667 32302 const uint8_t *read_end = buf;
668 32302 const uint8_t *read_start = buf;
669
670
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32302 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
671 FLACFrameInfo fi;
672
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123 if (frame_header_is_valid(avctx, buf, &fi)) {
673 115 s->duration = fi.blocksize;
674
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115 if (!avctx->sample_rate)
675 avctx->sample_rate = fi.samplerate;
676
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115 if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS) {
677 fpc->pc->pts = fi.frame_or_sample_num;
678 if (!fi.is_var_size)
679 fpc->pc->pts *= fi.blocksize;
680 }
681 }
682 123 *poutbuf = buf;
683 123 *poutbuf_size = buf_size;
684 123 return buf_size;
685 }
686
687 32179 fpc->avctx = avctx;
688
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32179 if (fpc->best_header_valid)
689 2363 return get_best_header(fpc, poutbuf, poutbuf_size);
690
691 /* If a best_header was found last call remove it with the buffer data. */
692
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29816 if (fpc->best_header && fpc->best_header->best_child) {
693 FLACHeaderMarker *temp;
694 2478 FLACHeaderMarker *best_child = fpc->best_header->best_child;
695
696 /* Remove headers in list until the end of the best_header. */
697
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4956 for (curr = fpc->headers; curr != best_child; curr = temp) {
698
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2478 if (curr != fpc->best_header) {
699 av_log(avctx, AV_LOG_DEBUG,
700 "dropping low score %i frame header from offset %i to %i\n",
701 curr->max_score, curr->offset, curr->next->offset);
702 }
703 2478 temp = curr->next;
704 2478 av_free(curr);
705 2478 fpc->nb_headers_buffered--;
706 }
707 /* Release returned data from ring buffer. */
708 2478 flac_fifo_drain(&fpc->fifo_buf, best_child->offset);
709
710 /* Fix the offset for the headers remaining to match the new buffer. */
711
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21409 for (curr = best_child->next; curr; curr = curr->next)
712 18931 curr->offset -= best_child->offset;
713
714 2478 best_child->offset = 0;
715 2478 fpc->headers = best_child;
716
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2478 if (fpc->nb_headers_buffered >= FLAC_MIN_HEADERS) {
717 29 fpc->best_header = best_child;
718 29 return get_best_header(fpc, poutbuf, poutbuf_size);
719 }
720 2449 fpc->best_header = NULL;
721
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27338 } else if (fpc->best_header) {
722 /* No end frame no need to delete the buffer; probably eof */
723 FLACHeaderMarker *temp;
724
725
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34 for (curr = fpc->headers; curr != fpc->best_header; curr = temp) {
726 temp = curr->next;
727 av_free(curr);
728 fpc->nb_headers_buffered--;
729 }
730 34 fpc->headers = fpc->best_header->next;
731 34 av_freep(&fpc->best_header);
732 34 fpc->nb_headers_buffered--;
733 }
734
735 /* Find and score new headers. */
736 /* buf_size is zero when flushing, so check for this since we do */
737 /* not want to try to read more input once we have found the end. */
738 /* Also note that buf can't be NULL. */
739
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61672 while ((buf_size && read_end < buf + buf_size &&
740
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29516 fpc->nb_headers_buffered < FLAC_MIN_HEADERS)
741
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34562 || (!buf_size && !fpc->end_padded)) {
742 int start_offset, ret;
743
744 /* Pad the end once if EOF, to check the final region for headers. */
745
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29553 if (!buf_size) {
746 37 fpc->end_padded = 1;
747 37 read_end = read_start + MAX_FRAME_HEADER_SIZE;
748 } else {
749 /* The maximum read size is the upper-bound of what the parser
750 needs to have the required number of frames buffered */
751 29516 int nb_desired = FLAC_MIN_HEADERS - fpc->nb_headers_buffered + 1;
752
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29516 read_end = read_end + FFMIN(buf + buf_size - read_end,
753 nb_desired * FLAC_AVG_FRAME_SIZE);
754 }
755
756
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29553 if (!flac_fifo_space(&fpc->fifo_buf) &&
757 1 flac_fifo_size(&fpc->fifo_buf) / FLAC_AVG_FRAME_SIZE >
758
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1 fpc->nb_headers_buffered * 20) {
759 /* There is less than one valid flac header buffered for 20 headers
760 * buffered. Therefore the fifo is most likely filled with invalid
761 * data and the input is not a flac file. */
762 goto handle_error;
763 }
764
765 /* Fill the buffer. */
766
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29553 if (buf_size) {
767 29516 ret = flac_fifo_write(&fpc->fifo_buf, read_start,
768 29516 read_end - read_start);
769 } else {
770 37 int8_t pad[MAX_FRAME_HEADER_SIZE] = { 0 };
771 37 ret = flac_fifo_write(&fpc->fifo_buf, pad, sizeof(pad));
772 }
773
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29553 if (ret < 0) {
774 av_log(avctx, AV_LOG_ERROR, "Error buffering data\n");
775 goto handle_error;
776 }
777
778 /* Tag headers and update sequences. */
779 29553 start_offset = flac_fifo_size(&fpc->fifo_buf) -
780 29553 ((read_end - read_start) + (MAX_FRAME_HEADER_SIZE - 1));
781 29553 start_offset = FFMAX(0, start_offset);
782 29553 nb_headers = find_new_headers(fpc, start_offset);
783
784
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29553 if (nb_headers < 0) {
785 av_log(avctx, AV_LOG_ERROR,
786 "find_new_headers couldn't allocate FLAC header\n");
787 goto handle_error;
788 }
789
790 29553 fpc->nb_headers_buffered = nb_headers;
791 /* Wait till FLAC_MIN_HEADERS to output a valid frame. */
792
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29553 if (!fpc->end_padded && fpc->nb_headers_buffered < FLAC_MIN_HEADERS) {
793
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27147 if (read_end < buf + buf_size) {
794 read_start = read_end;
795 continue;
796 } else {
797 27147 goto handle_error;
798 }
799 }
800
801 /* If headers found, update the scores since we have longer chains. */
802
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2406 if (fpc->end_padded || fpc->nb_headers_found)
803 2406 score_sequences(fpc);
804
805 /* restore the state pre-padding */
806
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2406 if (fpc->end_padded) {
807 37 int empty = flac_fifo_size(&fpc->fifo_buf) == MAX_FRAME_HEADER_SIZE;
808 37 int warp = fpc->fifo_buf.wptr - fpc->fifo_buf.buffer < MAX_FRAME_HEADER_SIZE;
809 /* HACK: drain the tail of the fifo */
810 37 fpc->fifo_buf.wptr -= MAX_FRAME_HEADER_SIZE;
811
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37 if (warp) {
812 fpc->fifo_buf.wptr += fpc->fifo_buf.end -
813 fpc->fifo_buf.buffer;
814 }
815 37 fpc->fifo_buf.empty = empty;
816 37 read_start = read_end = NULL;
817 }
818 }
819
820
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27496 for (curr = fpc->headers; curr; curr = curr->next) {
821
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24856 if (!fpc->best_header || curr->max_score > fpc->best_header->max_score) {
822 200 fpc->best_header = curr;
823 }
824 }
825
826
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2640 if (fpc->best_header && fpc->best_header->max_score <= 0) {
827 // Only accept a bad header if there is no other option to continue
828 if (!buf_size || read_end != buf || fpc->nb_headers_buffered < FLAC_MIN_HEADERS)
829 fpc->best_header = NULL;
830 }
831
832
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2640 if (fpc->best_header) {
833 2606 fpc->best_header_valid = 1;
834
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2606 if (fpc->best_header->offset > 0) {
835 /* Output a junk frame. */
836 106 av_log(avctx, AV_LOG_DEBUG, "Junk frame till offset %i\n",
837 106 fpc->best_header->offset);
838
839 /* Set duration to 0. It is unknown or invalid in a junk frame. */
840 106 s->duration = 0;
841 106 *poutbuf_size = fpc->best_header->offset;
842 106 *poutbuf = flac_fifo_read_wrap(fpc, 0, *poutbuf_size,
843 &fpc->wrap_buf,
844 &fpc->wrap_buf_allocated_size);
845
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115 return buf_size ? (read_end - buf) : (fpc->best_header->offset -
846 9 flac_fifo_size(&fpc->fifo_buf));
847 }
848
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2500 if (!buf_size)
849 228 return get_best_header(fpc, poutbuf, poutbuf_size);
850 }
851
852 2306 handle_error:
853 29453 *poutbuf = NULL;
854 29453 *poutbuf_size = 0;
855
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29453 return buf_size ? read_end - buf : 0;
856 }
857
858 204 static av_cold int flac_parse_init(AVCodecParserContext *c)
859 {
860 204 FLACParseContext *fpc = c->priv_data;
861 int ret;
862
863 204 fpc->pc = c;
864 /* There will generally be FLAC_MIN_HEADERS buffered in the fifo before
865 it drains. This is allocated early to avoid slow reallocation. */
866 204 ret = flac_fifo_alloc(&fpc->fifo_buf, (FLAC_MIN_HEADERS + 3) * FLAC_AVG_FRAME_SIZE);
867
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204 if (ret < 0) {
868 av_log(fpc->avctx, AV_LOG_ERROR,
869 "couldn't allocate fifo_buf\n");
870 return AVERROR(ENOMEM);
871 }
872 204 return 0;
873 }
874
875 204 static void flac_parse_close(AVCodecParserContext *c)
876 {
877 204 FLACParseContext *fpc = c->priv_data;
878 204 FLACHeaderMarker *curr = fpc->headers, *temp;
879
880
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1537 while (curr) {
881 1333 temp = curr->next;
882 1333 av_free(curr);
883 1333 curr = temp;
884 }
885 204 fpc->headers = NULL;
886 204 flac_fifo_free(&fpc->fifo_buf);
887 204 av_freep(&fpc->wrap_buf);
888 204 }
889
890 const AVCodecParser ff_flac_parser = {
891 .codec_ids = { AV_CODEC_ID_FLAC },
892 .priv_data_size = sizeof(FLACParseContext),
893 .parser_init = flac_parse_init,
894 .parser_parse = flac_parse,
895 .parser_close = flac_parse_close,
896 };
897