FFmpeg: libavcodec/parser.c Source File

FFmpeg
parser.c
Go to the documentation of this file.
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 
33  static AVCodecParser *av_first_parser = NULL;
34 
35  AVCodecParser *av_parser_next(const AVCodecParser *p)
36 {
37  if (p)
38  return p->next;
39  else
40  return av_first_parser;
41 }
42 
43  void av_register_codec_parser(AVCodecParser *parser)
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 
50  AVCodecParserContext *av_parser_init(int codec_id)
51 {
52  AVCodecParserContext *s = NULL;
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;
78  s->pict_type = AV_PICTURE_TYPE_I;
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 
131  int av_parser_parse2(AVCodecParserContext *s, AVCodecContext *avctx,
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;
137  uint8_t dummy_buf[FF_INPUT_BUFFER_PADDING_SIZE];
138 
139  if (!(s->flags & PARSER_FLAG_FETCHED_OFFSET)) {
140  s->next_frame_offset =
141  s->cur_offset = pos;
142  s->flags |= PARSER_FLAG_FETCHED_OFFSET;
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 */
174  s->frame_offset = s->next_frame_offset;
175 
176  /* offset of the next frame */
177  s->next_frame_offset = s->cur_offset + index;
178  s->fetch_timestamp = 1;
179  }
180  if (index < 0)
181  index = 0;
182  s->cur_offset += index;
183  return index;
184 }
185 
186  int av_parser_change(AVCodecParserContext *s, AVCodecContext *avctx,
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 
221  void av_parser_close(AVCodecParserContext *s)
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 +
255  FF_INPUT_BUFFER_PADDING_SIZE);
256 
257  if (!new_buffer) {
258  av_log(NULL, AV_LOG_ERROR, "Failed to reallocate parser buffer to %d\n", *buf_size + pc->index + FF_INPUT_BUFFER_PADDING_SIZE);
259  pc->index = 0;
260  return AVERROR(ENOMEM);
261  }
262  pc->buffer = new_buffer;
263  memcpy(&pc->buffer[pc->index], *buf, *buf_size);
264  pc->index += *buf_size;
265  return -1;
266  }
267 
268  *buf_size =
269  pc->overread_index = pc->index + next;
270 
271  /* append to buffer */
272  if (pc->index) {
273  void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
274  next + pc->index +
275  FF_INPUT_BUFFER_PADDING_SIZE);
276  if (!new_buffer) {
277  av_log(NULL, AV_LOG_ERROR, "Failed to reallocate parser buffer to %d\n", next + pc->index + FF_INPUT_BUFFER_PADDING_SIZE);
278  pc->overread_index =
279  pc->index = 0;
280  return AVERROR(ENOMEM);
281  }
282  pc->buffer = new_buffer;
283  if (next > -FF_INPUT_BUFFER_PADDING_SIZE)
284  memcpy(&pc->buffer[pc->index], *buf,
285  next + FF_INPUT_BUFFER_PADDING_SIZE);
286  pc->index = 0;
287  *buf = pc->buffer;
288  }
289 
290  /* store overread bytes */
291  for (; next < 0; next++) {
292  pc->state = pc->state << 8 | pc->buffer[pc->last_index + next];
293  pc->state64 = pc->state64 << 8 | pc->buffer[pc->last_index + next];
294  pc->overread++;
295  }
296 
297  if (pc->overread) {
298  ff_dlog(NULL, "overread %d, state:%X next:%d index:%d o_index:%d\n",
299  pc->overread, pc->state, next, pc->index, pc->overread_index);
300  ff_dlog(NULL, "%X %X %X %X\n",
301  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
302  }
303 
304  return 0;
305 }
306 
307  void ff_parse_close(AVCodecParserContext *s)
308 {
309  ParseContext *pc = s->priv_data;
310 
311  av_freep(&pc->buffer);
312 }
313 
314  int ff_mpeg4video_split(AVCodecContext *avctx, const uint8_t *buf, int buf_size)
315 {
316  uint32_t state = -1;
317  const uint8_t *ptr = buf, *end = buf + buf_size;
318 
319  while (ptr < end) {
320  ptr = avpriv_find_start_code(ptr, end, &state);
321  if (state == 0x1B3 || state == 0x1B6)
322  return ptr - 4 - buf;
323  }
324 
325  return 0;
326 }
AVCodecParser::parser_init
int(* parser_init)(AVCodecParserContext *s)
Definition: avcodec.h:4428
NULL
#define NULL
Definition: coverity.c:32
s
const char * s
Definition: avisynth_c.h:631
AV_CODEC_ID_NONE
Definition: avcodec.h:103
mem.h
memory handling functions
AVCodecParserContext::next_frame_offset
int64_t next_frame_offset
Definition: avcodec.h:4253
AVCodecParser::codec_ids
int codec_ids[5]
Definition: avcodec.h:4426
AVCodecParserContext::cur_frame_pos
int64_t cur_frame_pos[AV_PARSER_PTS_NB]
Position of the packet in file.
Definition: avcodec.h:4363
AVCodecParserContext::dts_ref_dts_delta
int dts_ref_dts_delta
Offset of the current timestamp against last timestamp sync point in units of AVCodecContext.time_base.
Definition: avcodec.h:4342
ff_mpeg4video_split
int ff_mpeg4video_split(AVCodecContext *avctx, const uint8_t *buf, int buf_size)
Definition: parser.c:314
AVCodecParserContext::cur_offset
int64_t cur_offset
Definition: avcodec.h:4251
av_assert0
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
if
if()
Definition: avfilter.c:975
uint8_t
uint8_t
Definition: audio_convert.c:194
av_malloc
#define av_malloc(s)
Definition: tableprint_vlc.h:31
av_parser_change
int av_parser_change(AVCodecParserContext *s, AVCodecContext *avctx, uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size, int keyframe)
Definition: parser.c:186
CODEC_FLAG_GLOBAL_HEADER
#define CODEC_FLAG_GLOBAL_HEADER
Place global headers in extradata instead of every keyframe.
Definition: avcodec.h:758
end
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:67
AVCodecContext::extradata
uint8_t * extradata
some codecs need / can use extradata like Huffman tables.
Definition: avcodec.h:1355
AVCodecParser::next
struct AVCodecParser * next
Definition: avcodec.h:4437
AVCodecParser::parser_parse
int(* parser_parse)(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition: avcodec.h:4431
size
ptrdiff_t size
Definition: opengl_enc.c:101
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
avpriv_find_start_code
const uint8_t * avpriv_find_start_code(const uint8_t *p, const uint8_t *end, uint32_t *state)
ParseContext::buffer_size
unsigned int buffer_size
Definition: parser.h:32
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
avpriv_atomic_ptr_cas
#define avpriv_atomic_ptr_cas
Definition: atomic_gcc.h:60
AVCodecParserContext::pos
int64_t pos
Byte position of currently parsed frame in stream.
Definition: avcodec.h:4368
av_fast_realloc
void * av_fast_realloc(void *ptr, unsigned int *size, size_t min_size)
Reallocate the given block if it is not large enough, otherwise do nothing.
Definition: mem.c:478
AVCodecParser::priv_data_size
int priv_data_size
Definition: avcodec.h:4427
AVCodecParserContext::parser
struct AVCodecParser * parser
Definition: avcodec.h:4249
ff_combine_frame
int ff_combine_frame(ParseContext *pc, int next, const uint8_t **buf, int *buf_size)
Combine the (truncated) bitstream to a complete frame.
Definition: parser.c:231
AVERROR
#define AVERROR(e)
Definition: error.h:43
AVCodecContext::flags
int flags
CODEC_FLAG_*.
Definition: avcodec.h:1335
avassert.h
simple assert() macros that are a bit more flexible than ISO C assert().
ParseContext::overread_index
int overread_index
the index into ParseContext.buffer of the overread bytes
Definition: parser.h:36
AVCodecParserContext::priv_data
void * priv_data
Definition: avcodec.h:4248
AVCodecParserContext::cur_frame_dts
int64_t cur_frame_dts[AV_PARSER_PTS_NB]
Definition: avcodec.h:4278
AV_PARSER_PTS_NB
#define AV_PARSER_PTS_NB
Definition: avcodec.h:4274
av_parser_next
AVCodecParser * av_parser_next(const AVCodecParser *p)
Definition: parser.c:35
codec_id
enum AVCodecID codec_id
Definition: mov_chan.c:433
ff_parse_close
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:307
FF_INPUT_BUFFER_PADDING_SIZE
#define FF_INPUT_BUFFER_PADDING_SIZE
Required number of additionally allocated bytes at the end of the input bitstream for decoding...
Definition: avcodec.h:630
AV_PICTURE_TYPE_I
Intra.
Definition: avutil.h:267
ParseContext::overread
int overread
the number of bytes which where irreversibly read from the next frame
Definition: parser.h:35
ParseContext::last_index
int last_index
Definition: parser.h:31
av_parser_parse2
int av_parser_parse2(AVCodecParserContext *s, AVCodecContext *avctx, uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size, int64_t pts, int64_t dts, int64_t pos)
Parse a packet.
Definition: parser.c:131
ret
ret
Definition: avfilter.c:974
AVCodecParser::parser_close
void(* parser_close)(AVCodecParserContext *s)
Definition: avcodec.h:4435
AVCodecParserContext::offset
int64_t offset
byte offset from starting packet start
Definition: avcodec.h:4287
AVCodecParserContext::convergence_duration
int64_t convergence_duration
Time difference in stream time base units from the pts of this packet to the point at which the outpu...
Definition: avcodec.h:4315
av_parser_close
void av_parser_close(AVCodecParserContext *s)
Definition: parser.c:221
AVCodecParserContext::cur_frame_end
int64_t cur_frame_end[AV_PARSER_PTS_NB]
Definition: avcodec.h:4288
AVCodecParserContext::cur_frame_pts
int64_t cur_frame_pts[AV_PARSER_PTS_NB]
Definition: avcodec.h:4277
AVCodecParserContext::last_pos
int64_t last_pos
Previous frame byte position.
Definition: avcodec.h:4373
AVCodecParserContext::pts_dts_delta
int pts_dts_delta
Presentation delay of current frame in units of AVCodecContext.time_base.
Definition: avcodec.h:4356
av_parser_init
AVCodecParserContext * av_parser_init(int codec_id)
Definition: parser.c:50
ParseContext::buffer
uint8_t * buffer
Definition: parser.h:29
ff_dlog
#define ff_dlog(ctx,...)
Definition: internal.h:54
AVCodecContext
main external API structure.
Definition: avcodec.h:1241
CODEC_FLAG2_LOCAL_HEADER
#define CODEC_FLAG2_LOCAL_HEADER
Place global headers at every keyframe instead of in extradata.
Definition: avcodec.h:767
AVCodecParserContext::cur_frame_start_index
int cur_frame_start_index
Definition: avcodec.h:4275
buf
void * buf
Definition: avisynth_c.h:553
ParseContext::state
uint32_t state
contains the last few bytes in MSB order
Definition: parser.h:33
AVCodecContext::extradata_size
int extradata_size
Definition: avcodec.h:1356
index
int index
Definition: gxfenc.c:89
ParseContext::state64
uint64_t state64
contains the last 8 bytes in MSB order
Definition: parser.h:37
av_register_codec_parser
void av_register_codec_parser(AVCodecParser *parser)
Definition: parser.c:43
av_first_parser
static AVCodecParser * av_first_parser
Definition: parser.c:33
END_NOT_FOUND
#define END_NOT_FOUND
Definition: parser.h:40
pts
static int64_t pts
Global timestamp for the audio frames.
Definition: transcode_aac.c:547
state
static uint32_t state
Definition: trasher.c:27
AVCodecParser::split
int(* split)(AVCodecContext *avctx, const uint8_t *buf, int buf_size)
Definition: avcodec.h:4436
internal.h
common internal api header.
PARSER_FLAG_FETCHED_OFFSET
#define PARSER_FLAG_FETCHED_OFFSET
Set if the parser has a valid file offset.
Definition: avcodec.h:4284
ParseContext::index
int index
Definition: parser.h:30
AVCodecParserContext::cur_frame_offset
int64_t cur_frame_offset[AV_PARSER_PTS_NB]
Definition: avcodec.h:4276
AVCodecParserContext::last_pts
int64_t last_pts
Definition: avcodec.h:4270
AVCodecParserContext::frame_offset
int64_t frame_offset
Definition: avcodec.h:4250
av_free
#define av_free(p)
Definition: tableprint_vlc.h:34
AVCodecParserContext::last_dts
int64_t last_dts
Definition: avcodec.h:4271
AVCodecParserContext::format
int format
The format of the coded data, corresponds to enum AVPixelFormat for video and for enum AVSampleFormat...
Definition: avcodec.h:4422
AVCodecContext::flags2
int flags2
CODEC_FLAG2_*.
Definition: avcodec.h:1342
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
ff_fetch_timestamp
void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove, int fuzzy)
Fetch timestamps for a specific byte within the current access unit.
Definition: parser.c:100
AVCodecParserContext::key_frame
int key_frame
Set by parser to 1 for key frames and 0 for non-key frames.
Definition: avcodec.h:4296
av_mallocz
void * av_mallocz(size_t size)
Allocate a block of size bytes with alignment suitable for all memory accesses (including vectors if ...
Definition: mem.c:250
AVCodecParserContext::dts_sync_point
int dts_sync_point
Synchronization point for start of timestamp generation.
Definition: avcodec.h:4327
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:241
Generated on Wed Jun 10 2015 01:56:47 for FFmpeg by   doxygen 1.8.6

AltStyle によって変換されたページ (->オリジナル) /