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/atomic.h"
27 #include "libavutil/mem.h"
28 
29 #include "parser.h"
30 
32 
34 {
35  if (p)
36  return p->next;
37  else
38  return av_first_parser;
39 }
40 
42 {
43  do {
44  parser->next = av_first_parser;
45  } while (parser->next != avpriv_atomic_ptr_cas((void * volatile *)&av_first_parser, parser->next, parser));
46 }
47 
49 {
50  AVCodecParserContext *s = NULL;
51  AVCodecParser *parser;
52  int ret;
53 
54  if (codec_id == AV_CODEC_ID_NONE)
55  return NULL;
56 
57  for (parser = av_first_parser; parser != NULL; parser = parser->next) {
58  if (parser->codec_ids[0] == codec_id ||
59  parser->codec_ids[1] == codec_id ||
60  parser->codec_ids[2] == codec_id ||
61  parser->codec_ids[3] == codec_id ||
62  parser->codec_ids[4] == codec_id)
63  goto found;
64  }
65  return NULL;
66 
67 found:
68  s = av_mallocz(sizeof(AVCodecParserContext));
69  if (!s)
70  goto err_out;
71  s->parser = parser;
72  s->priv_data = av_mallocz(parser->priv_data_size);
73  if (!s->priv_data)
74  goto err_out;
75  s->fetch_timestamp=1;
77  if (parser->parser_init) {
78  ret = parser->parser_init(s);
79  if (ret != 0)
80  goto err_out;
81  }
82  s->key_frame = -1;
83  s->convergence_duration = 0;
84  s->dts_sync_point = INT_MIN;
85  s->dts_ref_dts_delta = INT_MIN;
86  s->pts_dts_delta = INT_MIN;
87  return s;
88 
89 err_out:
90  if (s)
91  av_freep(&s->priv_data);
92  av_free(s);
93  return NULL;
94 }
95 
96 void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove)
97 {
98  int i;
99 
100  s->dts =
101  s->pts = AV_NOPTS_VALUE;
102  s->pos = -1;
103  s->offset = 0;
104  for (i = 0; i < AV_PARSER_PTS_NB; i++) {
105  if (s->cur_offset + off >= s->cur_frame_offset[i] &&
106  (s->frame_offset < s->cur_frame_offset[i] ||
107  (!s->frame_offset && !s->next_frame_offset)) && // first field/frame
108  // check disabled since MPEG-TS does not send complete PES packets
109  /*s->next_frame_offset + off <*/ s->cur_frame_end[i]){
110 
111  s->dts = s->cur_frame_dts[i];
112  s->pts = s->cur_frame_pts[i];
113  s->pos = s->cur_frame_pos[i];
114  s->offset = s->next_frame_offset - s->cur_frame_offset[i];
115  if (remove)
116  s->cur_frame_offset[i] = INT64_MAX;
117  if (s->cur_offset + off < s->cur_frame_end[i])
118  break;
119  }
120  }
121 }
122 
124  uint8_t **poutbuf, int *poutbuf_size,
125  const uint8_t *buf, int buf_size,
126  int64_t pts, int64_t dts, int64_t pos)
127 {
128  int index, i;
130 
131  if (!(s->flags & PARSER_FLAG_FETCHED_OFFSET)) {
132  s->next_frame_offset =
133  s->cur_offset = pos;
135  }
136 
137  if (buf_size == 0) {
138  /* padding is always necessary even if EOF, so we add it here */
139  memset(dummy_buf, 0, sizeof(dummy_buf));
140  buf = dummy_buf;
141  } else if (s->cur_offset + buf_size != s->cur_frame_end[s->cur_frame_start_index]) { /* skip remainder packets */
142  /* add a new packet descriptor */
143  i = (s->cur_frame_start_index + 1) & (AV_PARSER_PTS_NB - 1);
144  s->cur_frame_start_index = i;
145  s->cur_frame_offset[i] = s->cur_offset;
146  s->cur_frame_end[i] = s->cur_offset + buf_size;
147  s->cur_frame_pts[i] = pts;
148  s->cur_frame_dts[i] = dts;
149  s->cur_frame_pos[i] = pos;
150  }
151 
152  if (s->fetch_timestamp) {
153  s->fetch_timestamp = 0;
154  s->last_pts = s->pts;
155  s->last_dts = s->dts;
156  s->last_pos = s->pos;
157  ff_fetch_timestamp(s, 0, 0);
158  }
159  /* WARNING: the returned index can be negative */
160  index = s->parser->parser_parse(s, avctx, (const uint8_t **) poutbuf,
161  poutbuf_size, buf, buf_size);
162  /* update the file pointer */
163  if (*poutbuf_size) {
164  /* fill the data for the current frame */
166 
167  /* offset of the next frame */
169  s->fetch_timestamp = 1;
170  }
171  if (index < 0)
172  index = 0;
173  s->cur_offset += index;
174  return index;
175 }
176 
178  uint8_t **poutbuf, int *poutbuf_size,
179  const uint8_t *buf, int buf_size, int keyframe)
180 {
181  if (s && s->parser->split) {
182  if (avctx->flags & CODEC_FLAG_GLOBAL_HEADER ||
183  avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER) {
184  int i = s->parser->split(avctx, buf, buf_size);
185  buf += i;
186  buf_size -= i;
187  }
188  }
189 
190  /* cast to avoid warning about discarding qualifiers */
191  *poutbuf = (uint8_t *) buf;
192  *poutbuf_size = buf_size;
193  if (avctx->extradata) {
194  if (keyframe && (avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER)) {
195  int size = buf_size + avctx->extradata_size;
196 
197  *poutbuf_size = size;
198  *poutbuf = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);
199 
200  memcpy(*poutbuf, avctx->extradata, avctx->extradata_size);
201  memcpy(*poutbuf + avctx->extradata_size, buf,
202  buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
203  return 1;
204  }
205  }
206 
207  return 0;
208 }
209 
211 {
212  if (s) {
213  if (s->parser->parser_close)
214  s->parser->parser_close(s);
215  av_free(s->priv_data);
216  av_free(s);
217  }
218 }
219 
220 int ff_combine_frame(ParseContext *pc, int next,
221  const uint8_t **buf, int *buf_size)
222 {
223  if (pc->overread) {
224  av_dlog(NULL, "overread %d, state:%X next:%d index:%d o_index:%d\n",
225  pc->overread, pc->state, next, pc->index, pc->overread_index);
226  av_dlog(NULL, "%X %X %X %X\n",
227  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
228  }
229 
230  /* Copy overread bytes from last frame into buffer. */
231  for (; pc->overread > 0; pc->overread--)
232  pc->buffer[pc->index++] = pc->buffer[pc->overread_index++];
233 
234  /* flush remaining if EOF */
235  if (!*buf_size && next == END_NOT_FOUND)
236  next = 0;
237 
238  pc->last_index = pc->index;
239 
240  /* copy into buffer end return */
241  if (next == END_NOT_FOUND) {
242  void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
243  *buf_size + pc->index +
245 
246  if (!new_buffer) {
247  pc->index = 0;
248  return AVERROR(ENOMEM);
249  }
250  pc->buffer = new_buffer;
251  memcpy(&pc->buffer[pc->index], *buf, *buf_size);
252  pc->index += *buf_size;
253  return -1;
254  }
255 
256  *buf_size =
257  pc->overread_index = pc->index + next;
258 
259  /* append to buffer */
260  if (pc->index) {
261  void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
262  next + pc->index +
264  if (!new_buffer) {
265  pc->overread_index =
266  pc->index = 0;
267  return AVERROR(ENOMEM);
268  }
269  pc->buffer = new_buffer;
270  if (next > -FF_INPUT_BUFFER_PADDING_SIZE)
271  memcpy(&pc->buffer[pc->index], *buf,
273  pc->index = 0;
274  *buf = pc->buffer;
275  }
276 
277  /* store overread bytes */
278  for (; next < 0; next++) {
279  pc->state = pc->state << 8 | pc->buffer[pc->last_index + next];
280  pc->state64 = pc->state64 << 8 | pc->buffer[pc->last_index + next];
281  pc->overread++;
282  }
283 
284  if (pc->overread) {
285  av_dlog(NULL, "overread %d, state:%X next:%d index:%d o_index:%d\n",
286  pc->overread, pc->state, next, pc->index, pc->overread_index);
287  av_dlog(NULL, "%X %X %X %X\n",
288  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
289  }
290 
291  return 0;
292 }
293 
295 {
296  ParseContext *pc = s->priv_data;
297 
298  av_freep(&pc->buffer);
299 }
300 
301 int ff_mpeg4video_split(AVCodecContext *avctx, const uint8_t *buf, int buf_size)
302 {
303  int i;
304  uint32_t state = -1;
305 
306  for (i = 0; i < buf_size; i++) {
307  state = state << 8 | buf[i];
308  if (state == 0x1B3 || state == 0x1B6)
309  return i - 3;
310  }
311  return 0;
312 }