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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 3 | |
44 | /** minimum number of headers buffered and checked before returning frames */ | |
45 | #define FLAC_MIN_HEADERS 10 | |
46 | /** estimate for average size of a FLAC frame */ | |
47 | #define FLAC_AVG_FRAME_SIZE 8192 | |
48 | ||
49 | /** scoring settings for score_header */ | |
50 | #define FLAC_HEADER_BASE_SCORE 10 | |
51 | #define FLAC_HEADER_CHANGED_PENALTY 7 | |
52 | #define FLAC_HEADER_CRC_FAIL_PENALTY 50 | |
53 | #define FLAC_HEADER_NOT_PENALIZED_YET 100000 | |
54 | #define FLAC_HEADER_NOT_SCORED_YET -100000 | |
55 | ||
56 | /** largest possible size of flac header */ | |
57 | #define MAX_FRAME_HEADER_SIZE 16 | |
58 | ||
59 | typedef struct FLACHeaderMarker { | |
60 | int offset; /**< byte offset from start of FLACParseContext->buffer */ | |
61 | int *link_penalty; /**< 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 | ||
74 | typedef 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 | ||
94 | static 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 | */ | |
115 | static 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 | **/ | |
155 | static 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 | ||
166 | static 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(FLACHeaderMarker)); | |
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 | for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++) | |
196 | (*end_handle)->link_penalty[i] = FLAC_HEADER_NOT_PENALIZED_YET; | |
197 | ||
198 | fpc->nb_headers_found++; | |
199 | size++; | |
200 | } | |
201 | return size; | |
202 | } | |
203 | ||
204 | static int find_headers_search(FLACParseContext *fpc, uint8_t *buf, int buf_size, | |
205 | int search_start) | |
206 | ||
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 | size = find_headers_search_validate(fpc, search_start + i); | |
214 | } | |
215 | ||
216 | for (; i < buf_size - 1; i += 4) { | |
217 | x = AV_RB32(buf + i); | |
218 | if (((x & ~(x + 0x01010101)) & 0x80808080)) { | |
219 | for (j = 0; j < 4; j++) { | |
220 | if ((AV_RB16(buf + i + j) & 0xFFFE) == 0xFFF8) | |
221 | size = find_headers_search_validate(fpc, search_start + i + j); | |
222 | } | |
223 | } | |
224 | } | |
225 | return size; | |
226 | } | |
227 | ||
228 | static int find_new_headers(FLACParseContext *fpc, int search_start) | |
229 | { | |
230 | FLACHeaderMarker *end; | |
231 | int search_end, size = 0, read_len, temp; | |
232 | uint8_t *buf; | |
233 | fpc->nb_headers_found = 0; | |
234 | ||
235 | /* Search for a new header of at most 16 bytes. */ | |
236 | search_end = av_fifo_size(fpc->fifo_buf) - (MAX_FRAME_HEADER_SIZE - 1); | |
237 | read_len = search_end - search_start + 1; | |
238 | buf = flac_fifo_read(fpc, search_start, &read_len); | |
239 | size = find_headers_search(fpc, buf, read_len, search_start); | |
240 | search_start += read_len - 1; | |
241 | ||
242 | /* If fifo end was hit do the wrap around. */ | |
243 | if (search_start != search_end) { | |
244 | uint8_t wrap[2]; | |
245 | ||
246 | wrap[0] = buf[read_len - 1]; | |
247 | read_len = search_end - search_start + 1; | |
248 | ||
249 | /* search_start + 1 is the post-wrap offset in the fifo. */ | |
250 | buf = flac_fifo_read(fpc, search_start + 1, &read_len); | |
251 | wrap[1] = buf[0]; | |
252 | ||
253 | if ((AV_RB16(wrap) & 0xFFFE) == 0xFFF8) { | |
254 | temp = find_headers_search_validate(fpc, search_start); | |
255 | size = FFMAX(size, temp); | |
256 | } | |
257 | search_start++; | |
258 | ||
259 | /* Continue to do the last half of the wrap. */ | |
260 | temp = find_headers_search(fpc, buf, read_len, search_start); | |
261 | size = FFMAX(size, temp); | |
262 | search_start += read_len - 1; | |
263 | } | |
264 | ||
265 | /* Return the size even if no new headers were found. */ | |
266 | if (!size && fpc->headers) | |
267 | for (end = fpc->headers; end; end = end->next) | |
268 | size++; | |
269 | return size; | |
270 | } | |
271 | ||
272 | static int check_header_fi_mismatch(FLACParseContext *fpc, | |
273 | FLACFrameInfo *header_fi, | |
274 | FLACFrameInfo *child_fi, | |
275 | int log_level_offset) | |
276 | { | |
277 | int deduction = 0; | |
278 | if (child_fi->samplerate != header_fi->samplerate) { | |
279 | deduction += FLAC_HEADER_CHANGED_PENALTY; | |
280 | av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset, | |
281 | "sample rate change detected in adjacent frames\n"); | |
282 | } | |
283 | if (child_fi->bps != header_fi->bps) { | |
284 | deduction += FLAC_HEADER_CHANGED_PENALTY; | |
285 | av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset, | |
286 | "bits per sample change detected in adjacent frames\n"); | |
287 | } | |
288 | if (child_fi->is_var_size != header_fi->is_var_size) { | |
289 | /* Changing blocking strategy not allowed per the spec */ | |
290 | deduction += FLAC_HEADER_BASE_SCORE; | |
291 | av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset, | |
292 | "blocking strategy change detected in adjacent frames\n"); | |
293 | } | |
294 | if (child_fi->channels != header_fi->channels) { | |
295 | deduction += FLAC_HEADER_CHANGED_PENALTY; | |
296 | av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset, | |
297 | "number of channels change detected in adjacent frames\n"); | |
298 | } | |
299 | return deduction; | |
300 | } | |
301 | ||
302 | static int check_header_mismatch(FLACParseContext *fpc, | |
303 | FLACHeaderMarker *header, | |
304 | FLACHeaderMarker *child, | |
305 | int log_level_offset) | |
306 | { | |
307 | FLACFrameInfo *header_fi = &header->fi, *child_fi = &child->fi; | |
308 | int deduction, deduction_expected = 0, i; | |
309 | deduction = check_header_fi_mismatch(fpc, header_fi, child_fi, | |
310 | log_level_offset); | |
311 | /* Check sample and frame numbers. */ | |
312 | if ((child_fi->frame_or_sample_num - header_fi->frame_or_sample_num | |
313 | != header_fi->blocksize) && | |
314 | (child_fi->frame_or_sample_num | |
315 | != header_fi->frame_or_sample_num + 1)) { | |
316 | FLACHeaderMarker *curr; | |
317 | int expected_frame_num, expected_sample_num; | |
318 | /* If there are frames in the middle we expect this deduction, | |
319 | as they are probably valid and this one follows it */ | |
320 | ||
321 | expected_frame_num = expected_sample_num = header_fi->frame_or_sample_num; | |
322 | curr = header; | |
323 | while (curr != child) { | |
324 | /* Ignore frames that failed all crc checks */ | |
325 | for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS; i++) { | |
326 | if (curr->link_penalty[i] < FLAC_HEADER_CRC_FAIL_PENALTY) { | |
327 | expected_frame_num++; | |
328 | expected_sample_num += curr->fi.blocksize; | |
329 | break; | |
330 | } | |
331 | } | |
332 | curr = curr->next; | |
333 | } | |
334 | ||
335 | if (expected_frame_num == child_fi->frame_or_sample_num || | |
336 | expected_sample_num == child_fi->frame_or_sample_num) | |
337 | deduction_expected = deduction ? 0 : 1; | |
338 | ||
339 | deduction += FLAC_HEADER_CHANGED_PENALTY; | |
340 | av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset, | |
341 | "sample/frame number mismatch in adjacent frames\n"); | |
342 | } | |
343 | ||
344 | /* If we have suspicious headers, check the CRC between them */ | |
345 | if (deduction && !deduction_expected) { | |
346 | FLACHeaderMarker *curr; | |
347 | int read_len; | |
348 | uint8_t *buf; | |
349 | uint32_t crc = 1; | |
350 | int inverted_test = 0; | |
351 | ||
352 | /* Since CRC is expensive only do it if we haven't yet. | |
353 | This assumes a CRC penalty is greater than all other check penalties */ | |
354 | curr = header->next; | |
355 | for (i = 0; i < FLAC_MAX_SEQUENTIAL_HEADERS && curr != child; i++) | |
356 | curr = curr->next; | |
357 | ||
358 | if (header->link_penalty[i] < FLAC_HEADER_CRC_FAIL_PENALTY || | |
359 | header->link_penalty[i] == FLAC_HEADER_NOT_PENALIZED_YET) { | |
360 | FLACHeaderMarker *start, *end; | |
361 | ||
362 | /* Although overlapping chains are scored, the crc should never | |
363 | have to be computed twice for a single byte. */ | |
364 | start = header; | |
365 | end = child; | |
366 | if (i > 0 && | |
367 | header->link_penalty[i - 1] >= FLAC_HEADER_CRC_FAIL_PENALTY) { | |
368 | while (start->next != child) | |
369 | start = start->next; | |
370 | inverted_test = 1; | |
371 | } else if (i > 0 && | |
372 | header->next->link_penalty[i-1] >= | |
373 | FLAC_HEADER_CRC_FAIL_PENALTY ) { | |
374 | end = header->next; | |
375 | inverted_test = 1; | |
376 | } | |
377 | ||
378 | read_len = end->offset - start->offset; | |
379 | buf = flac_fifo_read(fpc, start->offset, &read_len); | |
380 | crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, buf, read_len); | |
381 | read_len = (end->offset - start->offset) - read_len; | |
382 | ||
383 | if (read_len) { | |
384 | buf = flac_fifo_read(fpc, end->offset - read_len, &read_len); | |
385 | crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI), crc, buf, read_len); | |
386 | } | |
387 | } | |
388 | ||
389 | if (!crc ^ !inverted_test) { | |
390 | deduction += FLAC_HEADER_CRC_FAIL_PENALTY; | |
391 | av_log(fpc->avctx, AV_LOG_WARNING + log_level_offset, | |
392 | "crc check failed from offset %i (frame %"PRId64") to %i (frame %"PRId64")\n", | |
393 | header->offset, header_fi->frame_or_sample_num, | |
394 | child->offset, child_fi->frame_or_sample_num); | |
395 | } | |
396 | } | |
397 | return deduction; | |
398 | } | |
399 | ||
400 | /** | |
401 | * Score a header. | |
402 | * | |
403 | * Give FLAC_HEADER_BASE_SCORE points to a frame for existing. | |
404 | * If it has children, (subsequent frames of which the preceding CRC footer | |
405 | * validates against this one,) then take the maximum score of the children, | |
406 | * with a penalty of FLAC_HEADER_CHANGED_PENALTY applied for each change to | |
407 | * bps, sample rate, channels, but not decorrelation mode, or blocksize, | |
408 | * because it can change often. | |
409 | **/ | |
410 | static int score_header(FLACParseContext *fpc, FLACHeaderMarker *header) | |
411 | { | |
412 | FLACHeaderMarker *child; | |
413 | int dist = 0; | |
414 | int child_score; | |
415 | int base_score = FLAC_HEADER_BASE_SCORE; | |
416 | if (header->max_score != FLAC_HEADER_NOT_SCORED_YET) | |
417 | return header->max_score; | |
418 | ||
419 | /* Modify the base score with changes from the last output header */ | |
420 | if (fpc->last_fi_valid) { | |
421 | /* Silence the log since this will be repeated if selected */ | |
422 | base_score -= check_header_fi_mismatch(fpc, &fpc->last_fi, &header->fi, | |
423 | AV_LOG_DEBUG); | |
424 | } | |
425 | ||
426 | header->max_score = base_score; | |
427 | ||
428 | /* Check and compute the children's scores. */ | |
429 | child = header->next; | |
430 | for (dist = 0; dist < FLAC_MAX_SEQUENTIAL_HEADERS && child; dist++) { | |
431 | /* Look at the child's frame header info and penalize suspicious | |
432 | changes between the headers. */ | |
433 | if (header->link_penalty[dist] == FLAC_HEADER_NOT_PENALIZED_YET) { | |
434 | header->link_penalty[dist] = check_header_mismatch(fpc, header, | |
435 | child, AV_LOG_DEBUG); | |
436 | } | |
437 | child_score = score_header(fpc, child) - header->link_penalty[dist]; | |
438 | ||
439 | if (FLAC_HEADER_BASE_SCORE + child_score > header->max_score) { | |
440 | /* Keep the child because the frame scoring is dynamic. */ | |
441 | header->best_child = child; | |
442 | header->max_score = base_score + child_score; | |
443 | } | |
444 | child = child->next; | |
445 | } | |
446 | ||
447 | return header->max_score; | |
448 | } | |
449 | ||
450 | static void score_sequences(FLACParseContext *fpc) | |
451 | { | |
452 | FLACHeaderMarker *curr; | |
453 | int best_score = 0;//FLAC_HEADER_NOT_SCORED_YET; | |
454 | /* First pass to clear all old scores. */ | |
455 | for (curr = fpc->headers; curr; curr = curr->next) | |
456 | curr->max_score = FLAC_HEADER_NOT_SCORED_YET; | |
457 | ||
458 | /* Do a second pass to score them all. */ | |
459 | for (curr = fpc->headers; curr; curr = curr->next) { | |
460 | if (score_header(fpc, curr) > best_score) { | |
461 | fpc->best_header = curr; | |
462 | best_score = curr->max_score; | |
463 | } | |
464 | } | |
465 | } | |
466 | ||
467 | static int get_best_header(FLACParseContext* fpc, const uint8_t **poutbuf, | |
468 | int *poutbuf_size) | |
469 | { | |
470 | FLACHeaderMarker *header = fpc->best_header; | |
471 | FLACHeaderMarker *child = header->best_child; | |
472 | if (!child) { | |
473 | *poutbuf_size = av_fifo_size(fpc->fifo_buf) - header->offset; | |
474 | } else { | |
475 | *poutbuf_size = child->offset - header->offset; | |
476 | ||
477 | /* If the child has suspicious changes, log them */ | |
478 | check_header_mismatch(fpc, header, child, 0); | |
479 | } | |
480 | ||
481 | if (header->fi.channels != fpc->avctx->channels || | |
482 | !fpc->avctx->channel_layout) { | |
483 | fpc->avctx->channels = header->fi.channels; | |
484 | ff_flac_set_channel_layout(fpc->avctx); | |
485 | } | |
486 | fpc->avctx->sample_rate = header->fi.samplerate; | |
487 | fpc->pc->duration = header->fi.blocksize; | |
488 | *poutbuf = flac_fifo_read_wrap(fpc, header->offset, *poutbuf_size, | |
489 | &fpc->wrap_buf, | |
490 | &fpc->wrap_buf_allocated_size); | |
491 | ||
492 | ||
493 | if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS){ | |
494 | if (header->fi.is_var_size) | |
495 | fpc->pc->pts = header->fi.frame_or_sample_num; | |
496 | else if (header->best_child) | |
497 | fpc->pc->pts = header->fi.frame_or_sample_num * header->fi.blocksize; | |
498 | } | |
499 | ||
500 | fpc->best_header_valid = 0; | |
501 | fpc->last_fi_valid = 1; | |
502 | fpc->last_fi = header->fi; | |
503 | ||
504 | /* Return the negative overread index so the client can compute pos. | |
505 | This should be the amount overread to the beginning of the child */ | |
506 | if (child) | |
507 | return child->offset - av_fifo_size(fpc->fifo_buf); | |
508 | return 0; | |
509 | } | |
510 | ||
511 | static int flac_parse(AVCodecParserContext *s, AVCodecContext *avctx, | |
512 | const uint8_t **poutbuf, int *poutbuf_size, | |
513 | const uint8_t *buf, int buf_size) | |
514 | { | |
515 | FLACParseContext *fpc = s->priv_data; | |
516 | FLACHeaderMarker *curr; | |
517 | int nb_headers; | |
518 | const uint8_t *read_end = buf; | |
519 | const uint8_t *read_start = buf; | |
520 | ||
521 | if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) { | |
522 | FLACFrameInfo fi; | |
523 | if (frame_header_is_valid(avctx, buf, &fi)) { | |
524 | s->duration = fi.blocksize; | |
525 | if (!avctx->sample_rate) | |
526 | avctx->sample_rate = fi.samplerate; | |
527 | if (fpc->pc->flags & PARSER_FLAG_USE_CODEC_TS){ | |
528 | fpc->pc->pts = fi.frame_or_sample_num; | |
529 | if (!fi.is_var_size) | |
530 | fpc->pc->pts *= fi.blocksize; | |
531 | } | |
532 | } | |
533 | *poutbuf = buf; | |
534 | *poutbuf_size = buf_size; | |
535 | return buf_size; | |
536 | } | |
537 | ||
538 | fpc->avctx = avctx; | |
539 | if (fpc->best_header_valid) | |
540 | return get_best_header(fpc, poutbuf, poutbuf_size); | |
541 | ||
542 | /* If a best_header was found last call remove it with the buffer data. */ | |
543 | if (fpc->best_header && fpc->best_header->best_child) { | |
544 | FLACHeaderMarker *temp; | |
545 | FLACHeaderMarker *best_child = fpc->best_header->best_child; | |
546 | ||
547 | /* Remove headers in list until the end of the best_header. */ | |
548 | for (curr = fpc->headers; curr != best_child; curr = temp) { | |
549 | if (curr != fpc->best_header) { | |
550 | av_log(avctx, AV_LOG_DEBUG, | |
551 | "dropping low score %i frame header from offset %i to %i\n", | |
552 | curr->max_score, curr->offset, curr->next->offset); | |
553 | } | |
554 | temp = curr->next; | |
555 | av_freep(&curr->link_penalty); | |
556 | av_free(curr); | |
557 | fpc->nb_headers_buffered--; | |
558 | } | |
559 | /* Release returned data from ring buffer. */ | |
560 | av_fifo_drain(fpc->fifo_buf, best_child->offset); | |
561 | ||
562 | /* Fix the offset for the headers remaining to match the new buffer. */ | |
563 | for (curr = best_child->next; curr; curr = curr->next) | |
564 | curr->offset -= best_child->offset; | |
565 | ||
566 | fpc->nb_headers_buffered--; | |
567 | best_child->offset = 0; | |
568 | fpc->headers = best_child; | |
569 | if (fpc->nb_headers_buffered >= FLAC_MIN_HEADERS) { | |
570 | fpc->best_header = best_child; | |
571 | return get_best_header(fpc, poutbuf, poutbuf_size); | |
572 | } | |
573 | fpc->best_header = NULL; | |
574 | } else if (fpc->best_header) { | |
575 | /* No end frame no need to delete the buffer; probably eof */ | |
576 | FLACHeaderMarker *temp; | |
577 | ||
578 | for (curr = fpc->headers; curr != fpc->best_header; curr = temp) { | |
579 | temp = curr->next; | |
580 | av_freep(&curr->link_penalty); | |
581 | av_free(curr); | |
582 | } | |
583 | fpc->headers = fpc->best_header->next; | |
584 | av_freep(&fpc->best_header->link_penalty); | |
585 | av_freep(&fpc->best_header); | |
586 | } | |
587 | ||
588 | /* Find and score new headers. */ | |
589 | /* buf_size is to zero when padding, so check for this since we do */ | |
590 | /* not want to try to read more input once we have found the end. */ | |
591 | /* Note that as (non-modified) parameters, buf can be non-NULL, */ | |
592 | /* while buf_size is 0. */ | |
593 | while ((buf && buf_size && read_end < buf + buf_size && | |
594 | fpc->nb_headers_buffered < FLAC_MIN_HEADERS) | |
595 | || ((!buf || !buf_size) && !fpc->end_padded)) { | |
596 | int start_offset; | |
597 | ||
598 | /* Pad the end once if EOF, to check the final region for headers. */ | |
599 | if (!buf || !buf_size) { | |
600 | fpc->end_padded = 1; | |
601 | buf_size = MAX_FRAME_HEADER_SIZE; | |
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 | /* Fill the buffer. */ | |
612 | if ( av_fifo_space(fpc->fifo_buf) < read_end - read_start | |
613 | && av_fifo_realloc2(fpc->fifo_buf, (read_end - read_start) + 2*av_fifo_size(fpc->fifo_buf)) < 0) { | |
614 | av_log(avctx, AV_LOG_ERROR, | |
615 | "couldn't reallocate buffer of size %"PTRDIFF_SPECIFIER"\n", | |
616 | (read_end - read_start) + av_fifo_size(fpc->fifo_buf)); | |
617 | goto handle_error; | |
618 | } | |
619 | ||
620 | if (buf && buf_size) { | |
621 | av_fifo_generic_write(fpc->fifo_buf, (void*) read_start, | |
622 | read_end - read_start, NULL); | |
623 | } else { | |
624 | int8_t pad[MAX_FRAME_HEADER_SIZE] = { 0 }; | |
625 | av_fifo_generic_write(fpc->fifo_buf, (void*) pad, sizeof(pad), NULL); | |
626 | } | |
627 | ||
628 | /* Tag headers and update sequences. */ | |
629 | start_offset = av_fifo_size(fpc->fifo_buf) - | |
630 | ((read_end - read_start) + (MAX_FRAME_HEADER_SIZE - 1)); | |
631 | start_offset = FFMAX(0, start_offset); | |
632 | nb_headers = find_new_headers(fpc, start_offset); | |
633 | ||
634 | if (nb_headers < 0) { | |
635 | av_log(avctx, AV_LOG_ERROR, | |
636 | "find_new_headers couldn't allocate FLAC header\n"); | |
637 | goto handle_error; | |
638 | } | |
639 | ||
640 | fpc->nb_headers_buffered = nb_headers; | |
641 | /* Wait till FLAC_MIN_HEADERS to output a valid frame. */ | |
642 | if (!fpc->end_padded && fpc->nb_headers_buffered < FLAC_MIN_HEADERS) { | |
643 | if (buf && read_end < buf + buf_size) { | |
644 | read_start = read_end; | |
645 | continue; | |
646 | } else { | |
647 | goto handle_error; | |
648 | } | |
649 | } | |
650 | ||
651 | /* If headers found, update the scores since we have longer chains. */ | |
652 | if (fpc->end_padded || fpc->nb_headers_found) | |
653 | score_sequences(fpc); | |
654 | ||
655 | /* restore the state pre-padding */ | |
656 | if (fpc->end_padded) { | |
657 | int warp = fpc->fifo_buf->wptr - fpc->fifo_buf->buffer < MAX_FRAME_HEADER_SIZE; | |
658 | /* HACK: drain the tail of the fifo */ | |
659 | fpc->fifo_buf->wptr -= MAX_FRAME_HEADER_SIZE; | |
660 | fpc->fifo_buf->wndx -= MAX_FRAME_HEADER_SIZE; | |
661 | if (warp) { | |
662 | fpc->fifo_buf->wptr += fpc->fifo_buf->end - | |
663 | fpc->fifo_buf->buffer; | |
664 | } | |
665 | buf_size = 0; | |
666 | read_start = read_end = NULL; | |
667 | } | |
668 | } | |
669 | ||
670 | for (curr = fpc->headers; curr; curr = curr->next) { | |
671 | if (curr->max_score > 0 && | |
672 | (!fpc->best_header || curr->max_score > fpc->best_header->max_score)) { | |
673 | fpc->best_header = curr; | |
674 | } | |
675 | } | |
676 | ||
677 | if (fpc->best_header) { | |
678 | fpc->best_header_valid = 1; | |
679 | if (fpc->best_header->offset > 0) { | |
680 | /* Output a junk frame. */ | |
681 | av_log(avctx, AV_LOG_DEBUG, "Junk frame till offset %i\n", | |
682 | fpc->best_header->offset); | |
683 | ||
684 | /* Set duration to 0. It is unknown or invalid in a junk frame. */ | |
685 | s->duration = 0; | |
686 | *poutbuf_size = fpc->best_header->offset; | |
687 | *poutbuf = flac_fifo_read_wrap(fpc, 0, *poutbuf_size, | |
688 | &fpc->wrap_buf, | |
689 | &fpc->wrap_buf_allocated_size); | |
690 | return buf_size ? (read_end - buf) : (fpc->best_header->offset - | |
691 | av_fifo_size(fpc->fifo_buf)); | |
692 | } | |
693 | if (!buf_size) | |
694 | return get_best_header(fpc, poutbuf, poutbuf_size); | |
695 | } | |
696 | ||
697 | handle_error: | |
698 | *poutbuf = NULL; | |
699 | *poutbuf_size = 0; | |
700 | return read_end - buf; | |
701 | } | |
702 | ||
703 | static av_cold int flac_parse_init(AVCodecParserContext *c) | |
704 | { | |
705 | FLACParseContext *fpc = c->priv_data; | |
706 | fpc->pc = c; | |
707 | /* There will generally be FLAC_MIN_HEADERS buffered in the fifo before | |
708 | it drains. This is allocated early to avoid slow reallocation. */ | |
709 | fpc->fifo_buf = av_fifo_alloc_array(FLAC_MIN_HEADERS + 3, FLAC_AVG_FRAME_SIZE); | |
710 | if (!fpc->fifo_buf) | |
711 | return AVERROR(ENOMEM); | |
712 | return 0; | |
713 | } | |
714 | ||
715 | static void flac_parse_close(AVCodecParserContext *c) | |
716 | { | |
717 | FLACParseContext *fpc = c->priv_data; | |
718 | FLACHeaderMarker *curr = fpc->headers, *temp; | |
719 | ||
720 | while (curr) { | |
721 | temp = curr->next; | |
722 | av_freep(&curr->link_penalty); | |
723 | av_free(curr); | |
724 | curr = temp; | |
725 | } | |
726 | av_fifo_freep(&fpc->fifo_buf); | |
f6fa7814 | 727 | av_freep(&fpc->wrap_buf); |
2ba45a60 DM |
728 | } |
729 | ||
730 | AVCodecParser ff_flac_parser = { | |
731 | .codec_ids = { AV_CODEC_ID_FLAC }, | |
732 | .priv_data_size = sizeof(FLACParseContext), | |
733 | .parser_init = flac_parse_init, | |
734 | .parser_parse = flac_parse, | |
735 | .parser_close = flac_parse_close, | |
736 | }; |