FFmpeg
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 <inttypes.h>
24 #include <stdint.h>
25 #include <string.h>
26 
27 #include "libavutil/avassert.h"
28 #include "libavutil/internal.h"
29 #include "libavutil/mem.h"
30 
31 #include "internal.h"
32 #include "parser.h"
33 
35 {
37  const AVCodecParser *parser;
38  void *i = 0;
39  int ret;
40 
42  return NULL;
43 
44  while ((parser = av_parser_iterate(&i))) {
45  if (parser->codec_ids[0] == codec_id ||
46  parser->codec_ids[1] == codec_id ||
47  parser->codec_ids[2] == codec_id ||
48  parser->codec_ids[3] == codec_id ||
49  parser->codec_ids[4] == codec_id)
50  goto found;
51  }
52  return NULL;
53 
54 found:
56  if (!s)
57  goto err_out;
58  s->parser = parser;
59  s->priv_data = av_mallocz(parser->priv_data_size);
60  if (!s->priv_data)
61  goto err_out;
62  s->fetch_timestamp=1;
63  s->pict_type = AV_PICTURE_TYPE_I;
64  if (parser->parser_init) {
65  ret = parser->parser_init(s);
66  if (ret != 0)
67  goto err_out;
68  }
69  s->key_frame = -1;
70  s->dts_sync_point = INT_MIN;
71  s->dts_ref_dts_delta = INT_MIN;
72  s->pts_dts_delta = INT_MIN;
73  s->format = -1;
74 
75  return s;
76 
77 err_out:
78  if (s)
79  av_freep(&s->priv_data);
80  av_free(s);
81  return NULL;
82 }
83 
84 void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove, int fuzzy)
85 {
86  int i;
87 
88  if (!fuzzy) {
89  s->dts =
90  s->pts = AV_NOPTS_VALUE;
91  s->pos = -1;
92  s->offset = 0;
93  }
94  for (i = 0; i < AV_PARSER_PTS_NB; i++) {
95  if (s->cur_offset + off >= s->cur_frame_offset[i] &&
96  (s->frame_offset < s->cur_frame_offset[i] ||
97  (!s->frame_offset && !s->next_frame_offset)) && // first field/frame
98  // check disabled since MPEG-TS does not send complete PES packets
99  /*s->next_frame_offset + off <*/ s->cur_frame_end[i]){
100 
101  if (!fuzzy || s->cur_frame_dts[i] != AV_NOPTS_VALUE) {
102  s->dts = s->cur_frame_dts[i];
103  s->pts = s->cur_frame_pts[i];
104  s->pos = s->cur_frame_pos[i];
105  s->offset = s->next_frame_offset - s->cur_frame_offset[i];
106  }
107  if (remove)
108  s->cur_frame_offset[i] = INT64_MAX;
109  if (s->cur_offset + off < s->cur_frame_end[i])
110  break;
111  }
112  }
113 }
114 
116  uint8_t **poutbuf, int *poutbuf_size,
117  const uint8_t *buf, int buf_size,
118  int64_t pts, int64_t dts, int64_t pos)
119 {
120  int index, i;
121  uint8_t dummy_buf[AV_INPUT_BUFFER_PADDING_SIZE];
122 
124 
125  /* Parsers only work for the specified codec ids. */
126  av_assert1(avctx->codec_id == s->parser->codec_ids[0] ||
127  avctx->codec_id == s->parser->codec_ids[1] ||
128  avctx->codec_id == s->parser->codec_ids[2] ||
129  avctx->codec_id == s->parser->codec_ids[3] ||
130  avctx->codec_id == s->parser->codec_ids[4]);
131 
132  if (!(s->flags & PARSER_FLAG_FETCHED_OFFSET)) {
133  s->next_frame_offset =
134  s->cur_offset = pos;
135  s->flags |= PARSER_FLAG_FETCHED_OFFSET;
136  }
137 
138  if (buf_size == 0) {
139  /* padding is always necessary even if EOF, so we add it here */
140  memset(dummy_buf, 0, sizeof(dummy_buf));
141  buf = dummy_buf;
142  } else if (s->cur_offset + buf_size != s->cur_frame_end[s->cur_frame_start_index]) { /* skip remainder packets */
143  /* add a new packet descriptor */
144  i = (s->cur_frame_start_index + 1) & (AV_PARSER_PTS_NB - 1);
145  s->cur_frame_start_index = i;
146  s->cur_frame_offset[i] = s->cur_offset;
147  s->cur_frame_end[i] = s->cur_offset + buf_size;
148  s->cur_frame_pts[i] = pts;
149  s->cur_frame_dts[i] = dts;
150  s->cur_frame_pos[i] = pos;
151  }
152 
153  if (s->fetch_timestamp) {
154  s->fetch_timestamp = 0;
155  s->last_pts = s->pts;
156  s->last_dts = s->dts;
157  s->last_pos = s->pos;
158  ff_fetch_timestamp(s, 0, 0, 0);
159  }
160  /* WARNING: the returned index can be negative */
161  index = s->parser->parser_parse(s, avctx, (const uint8_t **) poutbuf,
162  poutbuf_size, buf, buf_size);
163  av_assert0(index > -0x20000000); // The API does not allow returning AVERROR codes
164 #define FILL(name) if(s->name > 0 && avctx->name <= 0) avctx->name = s->name
165  if (avctx->codec_type == AVMEDIA_TYPE_VIDEO) {
166  FILL(field_order);
167  }
168 
169  /* update the file pointer */
170  if (*poutbuf_size) {
171  /* fill the data for the current frame */
172  s->frame_offset = s->next_frame_offset;
173 
174  /* offset of the next frame */
175  s->next_frame_offset = s->cur_offset + index;
176  s->fetch_timestamp = 1;
177  } else {
178  /* Don't return a pointer to dummy_buf. */
179  *poutbuf = NULL;
180  }
181  if (index < 0)
182  index = 0;
183  s->cur_offset += index;
184  return index;
185 }
186 
188 {
189  if (s) {
190  if (s->parser->parser_close)
191  s->parser->parser_close(s);
192  av_freep(&s->priv_data);
193  av_free(s);
194  }
195 }
196 
197 int ff_combine_frame(ParseContext *pc, int next,
198  const uint8_t **buf, int *buf_size)
199 {
200  if (pc->overread) {
201  ff_dlog(NULL, "overread %d, state:%"PRIX32" next:%d index:%d o_index:%d\n",
202  pc->overread, pc->state, next, pc->index, pc->overread_index);
203  ff_dlog(NULL, "%X %X %X %X\n",
204  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
205  }
206 
207  /* Copy overread bytes from last frame into buffer. */
208  for (; pc->overread > 0; pc->overread--)
209  pc->buffer[pc->index++] = pc->buffer[pc->overread_index++];
210 
211  if (next > *buf_size)
212  return AVERROR(EINVAL);
213 
214  /* flush remaining if EOF */
215  if (!*buf_size && next == END_NOT_FOUND)
216  next = 0;
217 
218  pc->last_index = pc->index;
219 
220  /* copy into buffer end return */
221  if (next == END_NOT_FOUND) {
222  void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
223  *buf_size + pc->index +
225 
226  if (!new_buffer) {
227  av_log(NULL, AV_LOG_ERROR, "Failed to reallocate parser buffer to %d\n", *buf_size + pc->index + AV_INPUT_BUFFER_PADDING_SIZE);
228  pc->index = 0;
229  return AVERROR(ENOMEM);
230  }
231  pc->buffer = new_buffer;
232  memcpy(&pc->buffer[pc->index], *buf, *buf_size);
233  pc->index += *buf_size;
234  return -1;
235  }
236 
237  av_assert0(next >= 0 || pc->buffer);
238 
239  *buf_size =
240  pc->overread_index = pc->index + next;
241 
242  /* append to buffer */
243  if (pc->index) {
244  void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
245  next + pc->index +
247  if (!new_buffer) {
248  av_log(NULL, AV_LOG_ERROR, "Failed to reallocate parser buffer to %d\n", next + pc->index + AV_INPUT_BUFFER_PADDING_SIZE);
249  pc->overread_index =
250  pc->index = 0;
251  return AVERROR(ENOMEM);
252  }
253  pc->buffer = new_buffer;
254  if (next > -AV_INPUT_BUFFER_PADDING_SIZE)
255  memcpy(&pc->buffer[pc->index], *buf,
257  pc->index = 0;
258  *buf = pc->buffer;
259  }
260 
261  if (next < -8) {
262  pc->overread += -8 - next;
263  next = -8;
264  }
265  /* store overread bytes */
266  for (; next < 0; next++) {
267  pc->state = pc->state << 8 | pc->buffer[pc->last_index + next];
268  pc->state64 = pc->state64 << 8 | pc->buffer[pc->last_index + next];
269  pc->overread++;
270  }
271 
272  if (pc->overread) {
273  ff_dlog(NULL, "overread %d, state:%"PRIX32" next:%d index:%d o_index:%d\n",
274  pc->overread, pc->state, next, pc->index, pc->overread_index);
275  ff_dlog(NULL, "%X %X %X %X\n",
276  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
277  }
278 
279  return 0;
280 }
281 
283 {
284  ParseContext *pc = s->priv_data;
285 
286  av_freep(&pc->buffer);
287 }
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
ParseContext::buffer_size
unsigned int buffer_size
Definition: parser.h:32
av_parser_iterate
const AVCodecParser * av_parser_iterate(void **opaque)
Iterate over all registered codec parsers.
Definition: parsers.c:78
ParseContext::overread_index
int overread_index
the index into ParseContext.buffer of the overread bytes
Definition: parser.h:36
index
fg index
Definition: ffmpeg_filter.c:168
ff_parse_close
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:282
internal.h
ParseContext::state
uint32_t state
contains the last few bytes in MSB order
Definition: parser.h:33
FILL
#define FILL(name)
ParseContext::last_index
int last_index
Definition: parser.h:31
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:84
ParseContext
Definition: parser.h:28
av_parser_init
AVCodecParserContext * av_parser_init(int codec_id)
Definition: parser.c:34
pts
static int64_t pts
Definition: transcode_aac.c:652
ParseContext::buffer
uint8_t * buffer
Definition: parser.h:29
avassert.h
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:181
av_fast_realloc
void * av_fast_realloc(void *ptr, unsigned int *size, size_t min_size)
Reallocate the given buffer if it is not large enough, otherwise do nothing.
Definition: mem.c:485
ParseContext::index
int index
Definition: parser.h:30
s
#define s(width, name)
Definition: cbs_vp9.c:257
ParseContext::overread
int overread
the number of bytes which where irreversibly read from the next frame
Definition: parser.h:35
av_assert0
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
codec_id
enum AVCodecID codec_id
Definition: vaapi_decode.c:369
AVCodecContext::codec_id
enum AVCodecID codec_id
Definition: avcodec.h:394
if
if(ret)
Definition: filter_design.txt:179
NULL
#define NULL
Definition: coverity.c:32
AVCodecParser::codec_ids
int codec_ids[5]
Definition: avcodec.h:2922
AV_PICTURE_TYPE_I
@ AV_PICTURE_TYPE_I
Intra.
Definition: avutil.h:274
ff_dlog
#define ff_dlog(a,...)
Definition: tableprint_vlc.h:29
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
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:197
i
int i
Definition: input.c:407
AV_CODEC_ID_NONE
@ AV_CODEC_ID_NONE
Definition: codec_id.h:48
internal.h
av_assert1
#define av_assert1(cond)
assert() equivalent, that does not lie in speed critical code.
Definition: avassert.h:53
AVCodecParser::parser_init
int(* parser_init)(AVCodecParserContext *s)
Definition: avcodec.h:2924
av_mallocz
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:244
parser.h
AVCodecParserContext
Definition: avcodec.h:2762
ret
ret
Definition: filter_design.txt:187
pos
unsigned int pos
Definition: spdifenc.c:412
AVCodecParser::priv_data_size
int priv_data_size
Definition: avcodec.h:2923
AV_INPUT_BUFFER_PADDING_SIZE
#define AV_INPUT_BUFFER_PADDING_SIZE
Definition: defs.h:40
AVCodecContext
main external API structure.
Definition: avcodec.h:384
PARSER_FLAG_FETCHED_OFFSET
#define PARSER_FLAG_FETCHED_OFFSET
Set if the parser has a valid file offset.
Definition: avcodec.h:2799
ParseContext::state64
uint64_t state64
contains the last 8 bytes in MSB order
Definition: parser.h:37
AVCodecContext::codec_type
enum AVMediaType codec_type
Definition: avcodec.h:392
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
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:115
mem.h
av_free
#define av_free(p)
Definition: tableprint_vlc.h:34
END_NOT_FOUND
#define END_NOT_FOUND
Definition: parser.h:40
AV_PARSER_PTS_NB
#define AV_PARSER_PTS_NB
Definition: avcodec.h:2789
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
AVCodecParser
Definition: avcodec.h:2921
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
av_parser_close
void av_parser_close(AVCodecParserContext *s)
Definition: parser.c:187