FFmpeg
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parser.c
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1 /*
2  * Audio and Video frame extraction
3  * Copyright (c) 2003 Fabrice Bellard
4  * Copyright (c) 2003 Michael Niedermayer
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 #include <stdint.h>
24 #include <string.h>
25 
26 #include "libavutil/avassert.h"
27 #include "libavutil/atomic.h"
28 #include "libavutil/mem.h"
29 
30 #include "internal.h"
31 #include "parser.h"
32 
34 
36 {
37  if (p)
38  return p->next;
39  else
40  return av_first_parser;
41 }
42 
44 {
45  do {
46  parser->next = av_first_parser;
47  } while (parser->next != avpriv_atomic_ptr_cas((void * volatile *)&av_first_parser, parser->next, parser));
48 }
49 
51 {
53  AVCodecParser *parser;
54  int ret;
55 
56  if (codec_id == AV_CODEC_ID_NONE)
57  return NULL;
58 
59  for (parser = av_first_parser; parser; parser = parser->next) {
60  if (parser->codec_ids[0] == codec_id ||
61  parser->codec_ids[1] == codec_id ||
62  parser->codec_ids[2] == codec_id ||
63  parser->codec_ids[3] == codec_id ||
64  parser->codec_ids[4] == codec_id)
65  goto found;
66  }
67  return NULL;
68 
69 found:
70  s = av_mallocz(sizeof(AVCodecParserContext));
71  if (!s)
72  goto err_out;
73  s->parser = parser;
74  s->priv_data = av_mallocz(parser->priv_data_size);
75  if (!s->priv_data)
76  goto err_out;
77  s->fetch_timestamp=1;
79  if (parser->parser_init) {
80  ret = parser->parser_init(s);
81  if (ret != 0)
82  goto err_out;
83  }
84  s->key_frame = -1;
85  s->convergence_duration = 0;
86  s->dts_sync_point = INT_MIN;
87  s->dts_ref_dts_delta = INT_MIN;
88  s->pts_dts_delta = INT_MIN;
89  s->format = -1;
90 
91  return s;
92 
93 err_out:
94  if (s)
95  av_freep(&s->priv_data);
96  av_free(s);
97  return NULL;
98 }
99 
100 void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove, int fuzzy)
101 {
102  int i;
103 
104  if (!fuzzy) {
105  s->dts =
106  s->pts = AV_NOPTS_VALUE;
107  s->pos = -1;
108  s->offset = 0;
109  }
110  for (i = 0; i < AV_PARSER_PTS_NB; i++) {
111  if (s->cur_offset + off >= s->cur_frame_offset[i] &&
112  (s->frame_offset < s->cur_frame_offset[i] ||
113  (!s->frame_offset && !s->next_frame_offset)) && // first field/frame
114  // check disabled since MPEG-TS does not send complete PES packets
115  /*s->next_frame_offset + off <*/ s->cur_frame_end[i]){
116 
117  if (!fuzzy || s->cur_frame_dts[i] != AV_NOPTS_VALUE) {
118  s->dts = s->cur_frame_dts[i];
119  s->pts = s->cur_frame_pts[i];
120  s->pos = s->cur_frame_pos[i];
121  s->offset = s->next_frame_offset - s->cur_frame_offset[i];
122  }
123  if (remove)
124  s->cur_frame_offset[i] = INT64_MAX;
125  if (s->cur_offset + off < s->cur_frame_end[i])
126  break;
127  }
128  }
129 }
130 
132  uint8_t **poutbuf, int *poutbuf_size,
133  const uint8_t *buf, int buf_size,
134  int64_t pts, int64_t dts, int64_t pos)
135 {
136  int index, i;
138 
139  if (!(s->flags & PARSER_FLAG_FETCHED_OFFSET)) {
140  s->next_frame_offset =
141  s->cur_offset = pos;
143  }
144 
145  if (buf_size == 0) {
146  /* padding is always necessary even if EOF, so we add it here */
147  memset(dummy_buf, 0, sizeof(dummy_buf));
148  buf = dummy_buf;
149  } else if (s->cur_offset + buf_size != s->cur_frame_end[s->cur_frame_start_index]) { /* skip remainder packets */
150  /* add a new packet descriptor */
151  i = (s->cur_frame_start_index + 1) & (AV_PARSER_PTS_NB - 1);
152  s->cur_frame_start_index = i;
153  s->cur_frame_offset[i] = s->cur_offset;
154  s->cur_frame_end[i] = s->cur_offset + buf_size;
155  s->cur_frame_pts[i] = pts;
156  s->cur_frame_dts[i] = dts;
157  s->cur_frame_pos[i] = pos;
158  }
159 
160  if (s->fetch_timestamp) {
161  s->fetch_timestamp = 0;
162  s->last_pts = s->pts;
163  s->last_dts = s->dts;
164  s->last_pos = s->pos;
165  ff_fetch_timestamp(s, 0, 0, 0);
166  }
167  /* WARNING: the returned index can be negative */
168  index = s->parser->parser_parse(s, avctx, (const uint8_t **) poutbuf,
169  poutbuf_size, buf, buf_size);
170  av_assert0(index > -0x20000000); // The API does not allow returning AVERROR codes
171  /* update the file pointer */
172  if (*poutbuf_size) {
173  /* fill the data for the current frame */
175 
176  /* offset of the next frame */
178  s->fetch_timestamp = 1;
179  }
180  if (index < 0)
181  index = 0;
182  s->cur_offset += index;
183  return index;
184 }
185 
187  uint8_t **poutbuf, int *poutbuf_size,
188  const uint8_t *buf, int buf_size, int keyframe)
189 {
190  if (s && s->parser->split) {
191  if (avctx->flags & CODEC_FLAG_GLOBAL_HEADER ||
192  avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER) {
193  int i = s->parser->split(avctx, buf, buf_size);
194  buf += i;
195  buf_size -= i;
196  }
197  }
198 
199  /* cast to avoid warning about discarding qualifiers */
200  *poutbuf = (uint8_t *) buf;
201  *poutbuf_size = buf_size;
202  if (avctx->extradata) {
203  if (keyframe && (avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER)) {
204  int size = buf_size + avctx->extradata_size;
205 
206  *poutbuf_size = size;
207  *poutbuf = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);
208  if (!*poutbuf)
209  return AVERROR(ENOMEM);
210 
211  memcpy(*poutbuf, avctx->extradata, avctx->extradata_size);
212  memcpy(*poutbuf + avctx->extradata_size, buf,
213  buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
214  return 1;
215  }
216  }
217 
218  return 0;
219 }
220 
222 {
223  if (s) {
224  if (s->parser->parser_close)
225  s->parser->parser_close(s);
226  av_freep(&s->priv_data);
227  av_free(s);
228  }
229 }
230 
231 int ff_combine_frame(ParseContext *pc, int next,
232  const uint8_t **buf, int *buf_size)
233 {
234  if (pc->overread) {
235  ff_dlog(NULL, "overread %d, state:%X next:%d index:%d o_index:%d\n",
236  pc->overread, pc->state, next, pc->index, pc->overread_index);
237  ff_dlog(NULL, "%X %X %X %X\n",
238  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
239  }
240 
241  /* Copy overread bytes from last frame into buffer. */
242  for (; pc->overread > 0; pc->overread--)
243  pc->buffer[pc->index++] = pc->buffer[pc->overread_index++];
244 
245  /* flush remaining if EOF */
246  if (!*buf_size && next == END_NOT_FOUND)
247  next = 0;
248 
249  pc->last_index = pc->index;
250 
251  /* copy into buffer end return */
252  if (next == END_NOT_FOUND) {
253  void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
254  *buf_size + pc->index +
256 
257  if (!new_buffer) {
258  pc->index = 0;
259  return AVERROR(ENOMEM);
260  }
261  pc->buffer = new_buffer;
262  memcpy(&pc->buffer[pc->index], *buf, *buf_size);
263  pc->index += *buf_size;
264  return -1;
265  }
266 
267  *buf_size =
268  pc->overread_index = pc->index + next;
269 
270  /* append to buffer */
271  if (pc->index) {
272  void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
273  next + pc->index +
275  if (!new_buffer) {
276  pc->overread_index =
277  pc->index = 0;
278  return AVERROR(ENOMEM);
279  }
280  pc->buffer = new_buffer;
281  if (next > -FF_INPUT_BUFFER_PADDING_SIZE)
282  memcpy(&pc->buffer[pc->index], *buf,
284  pc->index = 0;
285  *buf = pc->buffer;
286  }
287 
288  /* store overread bytes */
289  for (; next < 0; next++) {
290  pc->state = pc->state << 8 | pc->buffer[pc->last_index + next];
291  pc->state64 = pc->state64 << 8 | pc->buffer[pc->last_index + next];
292  pc->overread++;
293  }
294 
295  if (pc->overread) {
296  ff_dlog(NULL, "overread %d, state:%X next:%d index:%d o_index:%d\n",
297  pc->overread, pc->state, next, pc->index, pc->overread_index);
298  ff_dlog(NULL, "%X %X %X %X\n",
299  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
300  }
301 
302  return 0;
303 }
304 
306 {
307  ParseContext *pc = s->priv_data;
308 
309  av_freep(&pc->buffer);
310 }
311 
312 int ff_mpeg4video_split(AVCodecContext *avctx, const uint8_t *buf, int buf_size)
313 {
314  uint32_t state = -1;
315  const uint8_t *ptr = buf, *end = buf + buf_size;
316 
317  while (ptr < end) {
318  ptr = avpriv_find_start_code(ptr, end, &state);
319  if (state == 0x1B3 || state == 0x1B6)
320  return ptr - 4 - buf;
321  }
322 
323  return 0;
324 }