Libav
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 Libav.
7  *
8  * Libav 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  * Libav 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 Libav; 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/mem.h"
27 
28 #include "parser.h"
29 
31 
33 {
34  if (p)
35  return p->next;
36  else
37  return av_first_parser;
38 }
39 
41 {
42  parser->next = av_first_parser;
43  av_first_parser = parser;
44 }
45 
47 {
49  AVCodecParser *parser;
50  int ret;
51 
52  if (codec_id == AV_CODEC_ID_NONE)
53  return NULL;
54 
55  for (parser = av_first_parser; parser != NULL; parser = parser->next) {
56  if (parser->codec_ids[0] == codec_id ||
57  parser->codec_ids[1] == codec_id ||
58  parser->codec_ids[2] == codec_id ||
59  parser->codec_ids[3] == codec_id ||
60  parser->codec_ids[4] == codec_id)
61  goto found;
62  }
63  return NULL;
64 
65 found:
66  s = av_mallocz(sizeof(AVCodecParserContext));
67  if (!s)
68  return NULL;
69  s->parser = parser;
70  if (parser->priv_data_size) {
71  s->priv_data = av_mallocz(parser->priv_data_size);
72  if (!s->priv_data) {
73  av_free(s);
74  return NULL;
75  }
76  }
77  if (parser->parser_init) {
78  ret = parser->parser_init(s);
79  if (ret != 0) {
80  av_free(s->priv_data);
81  av_free(s);
82  return NULL;
83  }
84  }
85  s->fetch_timestamp = 1;
87  s->key_frame = -1;
88  s->convergence_duration = 0;
89  s->dts_sync_point = INT_MIN;
90  s->dts_ref_dts_delta = INT_MIN;
91  s->pts_dts_delta = INT_MIN;
92  return s;
93 }
94 
95 void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove)
96 {
97  int i;
98 
99  s->dts =
100  s->pts = AV_NOPTS_VALUE;
101  s->pos = -1;
102  s->offset = 0;
103  for (i = 0; i < AV_PARSER_PTS_NB; i++) {
104  if (s->cur_offset + off >= s->cur_frame_offset[i] &&
105  (s->frame_offset < s->cur_frame_offset[i] ||
106  (!s->frame_offset && !s->next_frame_offset)) &&
107  s->cur_frame_end[i]) {
108  s->dts = s->cur_frame_dts[i];
109  s->pts = s->cur_frame_pts[i];
110  s->pos = s->cur_frame_pos[i];
111  s->offset = s->next_frame_offset - s->cur_frame_offset[i];
112  if (remove)
113  s->cur_frame_offset[i] = INT64_MAX;
114  if (s->cur_offset + off < s->cur_frame_end[i])
115  break;
116  }
117  }
118 }
119 
121  uint8_t **poutbuf, int *poutbuf_size,
122  const uint8_t *buf, int buf_size,
123  int64_t pts, int64_t dts, int64_t pos)
124 {
125  int index, i;
127 
128  if (!(s->flags & PARSER_FLAG_FETCHED_OFFSET)) {
129  s->next_frame_offset =
130  s->cur_offset = pos;
132  }
133 
134  if (buf_size == 0) {
135  /* padding is always necessary even if EOF, so we add it here */
136  memset(dummy_buf, 0, sizeof(dummy_buf));
137  buf = dummy_buf;
138  } else if (s->cur_offset + buf_size != s->cur_frame_end[s->cur_frame_start_index]) { /* skip remainder packets */
139  /* add a new packet descriptor */
140  i = (s->cur_frame_start_index + 1) & (AV_PARSER_PTS_NB - 1);
141  s->cur_frame_start_index = i;
142  s->cur_frame_offset[i] = s->cur_offset;
143  s->cur_frame_end[i] = s->cur_offset + buf_size;
144  s->cur_frame_pts[i] = pts;
145  s->cur_frame_dts[i] = dts;
146  s->cur_frame_pos[i] = pos;
147  }
148 
149  if (s->fetch_timestamp) {
150  s->fetch_timestamp = 0;
151  s->last_pts = s->pts;
152  s->last_dts = s->dts;
153  s->last_pos = s->pos;
154  ff_fetch_timestamp(s, 0, 0);
155  }
156  /* WARNING: the returned index can be negative */
157  index = s->parser->parser_parse(s, avctx, (const uint8_t **) poutbuf,
158  poutbuf_size, buf, buf_size);
159  /* update the file pointer */
160  if (*poutbuf_size) {
161  /* fill the data for the current frame */
163 
164  /* offset of the next frame */
166  s->fetch_timestamp = 1;
167  }
168  if (index < 0)
169  index = 0;
170  s->cur_offset += index;
171  return index;
172 }
173 
175  uint8_t **poutbuf, int *poutbuf_size,
176  const uint8_t *buf, int buf_size, int keyframe)
177 {
178  if (s && s->parser->split) {
179  if (avctx->flags & CODEC_FLAG_GLOBAL_HEADER ||
180  avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER) {
181  int i = s->parser->split(avctx, buf, buf_size);
182  buf += i;
183  buf_size -= i;
184  }
185  }
186 
187  /* cast to avoid warning about discarding qualifiers */
188  *poutbuf = (uint8_t *) buf;
189  *poutbuf_size = buf_size;
190  if (avctx->extradata) {
191  if (keyframe && (avctx->flags2 & CODEC_FLAG2_LOCAL_HEADER)) {
192  int size = buf_size + avctx->extradata_size;
193 
194  *poutbuf_size = size;
195  *poutbuf = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);
196 
197  memcpy(*poutbuf, avctx->extradata, avctx->extradata_size);
198  memcpy(*poutbuf + avctx->extradata_size, buf,
199  buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
200  return 1;
201  }
202  }
203 
204  return 0;
205 }
206 
208 {
209  if (s) {
210  if (s->parser->parser_close)
211  s->parser->parser_close(s);
212  av_free(s->priv_data);
213  av_free(s);
214  }
215 }
216 
217 int ff_combine_frame(ParseContext *pc, int next,
218  const uint8_t **buf, int *buf_size)
219 {
220  if (pc->overread) {
221  av_dlog(NULL, "overread %d, state:%X next:%d index:%d o_index:%d\n",
222  pc->overread, pc->state, next, pc->index, pc->overread_index);
223  av_dlog(NULL, "%X %X %X %X\n",
224  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
225  }
226 
227  /* Copy overread bytes from last frame into buffer. */
228  for (; pc->overread > 0; pc->overread--)
229  pc->buffer[pc->index++] = pc->buffer[pc->overread_index++];
230 
231  /* flush remaining if EOF */
232  if (!*buf_size && next == END_NOT_FOUND)
233  next = 0;
234 
235  pc->last_index = pc->index;
236 
237  /* copy into buffer end return */
238  if (next == END_NOT_FOUND) {
239  void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
240  *buf_size + pc->index +
242 
243  if (!new_buffer)
244  return AVERROR(ENOMEM);
245  pc->buffer = new_buffer;
246  memcpy(&pc->buffer[pc->index], *buf, *buf_size);
247  pc->index += *buf_size;
248  return -1;
249  }
250 
251  *buf_size =
252  pc->overread_index = pc->index + next;
253 
254  /* append to buffer */
255  if (pc->index) {
256  void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
257  next + pc->index +
259 
260  if (!new_buffer)
261  return AVERROR(ENOMEM);
262  pc->buffer = new_buffer;
263  if (next > -FF_INPUT_BUFFER_PADDING_SIZE)
264  memcpy(&pc->buffer[pc->index], *buf,
266  pc->index = 0;
267  *buf = pc->buffer;
268  }
269 
270  /* store overread bytes */
271  for (; next < 0; next++) {
272  pc->state = pc->state << 8 | pc->buffer[pc->last_index + next];
273  pc->state64 = pc->state64 << 8 | pc->buffer[pc->last_index + next];
274  pc->overread++;
275  }
276 
277  if (pc->overread) {
278  av_dlog(NULL, "overread %d, state:%X next:%d index:%d o_index:%d\n",
279  pc->overread, pc->state, next, pc->index, pc->overread_index);
280  av_dlog(NULL, "%X %X %X %X\n",
281  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
282  }
283 
284  return 0;
285 }
286 
288 {
289  ParseContext *pc = s->priv_data;
290 
291  av_freep(&pc->buffer);
292 }
293 
294 int ff_mpeg4video_split(AVCodecContext *avctx, const uint8_t *buf, int buf_size)
295 {
296  int i;
297  uint32_t state = -1;
298 
299  for (i = 0; i < buf_size; i++) {
300  state = state << 8 | buf[i];
301  if (state == 0x1B3 || state == 0x1B6)
302  return i - 3;
303  }
304  return 0;
305 }