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/mem.h"
29 
30 #include "parser.h"
31 
33 {
35  const AVCodecParser *parser;
36  void *i = 0;
37  int ret;
38 
40  return NULL;
41 
42  while ((parser = av_parser_iterate(&i))) {
43  if (parser->codec_ids[0] == codec_id ||
44  parser->codec_ids[1] == codec_id ||
45  parser->codec_ids[2] == codec_id ||
46  parser->codec_ids[3] == codec_id ||
47  parser->codec_ids[4] == codec_id ||
48  parser->codec_ids[5] == codec_id ||
49  parser->codec_ids[6] == 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  avctx->codec_id == s->parser->codec_ids[5] ||
132  avctx->codec_id == s->parser->codec_ids[6]);
133 
134  if (!(s->flags & PARSER_FLAG_FETCHED_OFFSET)) {
135  s->next_frame_offset =
136  s->cur_offset = pos;
137  s->flags |= PARSER_FLAG_FETCHED_OFFSET;
138  }
139 
140  if (buf_size == 0) {
141  /* padding is always necessary even if EOF, so we add it here */
142  memset(dummy_buf, 0, sizeof(dummy_buf));
143  buf = dummy_buf;
144  } else if (s->cur_offset + buf_size != s->cur_frame_end[s->cur_frame_start_index]) { /* skip remainder packets */
145  /* add a new packet descriptor */
146  i = (s->cur_frame_start_index + 1) & (AV_PARSER_PTS_NB - 1);
147  s->cur_frame_start_index = i;
148  s->cur_frame_offset[i] = s->cur_offset;
149  s->cur_frame_end[i] = s->cur_offset + buf_size;
150  s->cur_frame_pts[i] = pts;
151  s->cur_frame_dts[i] = dts;
152  s->cur_frame_pos[i] = pos;
153  }
154 
155  if (s->fetch_timestamp) {
156  s->fetch_timestamp = 0;
157  s->last_pts = s->pts;
158  s->last_dts = s->dts;
159  s->last_pos = s->pos;
160  ff_fetch_timestamp(s, 0, 0, 0);
161  }
162  /* WARNING: the returned index can be negative */
163  index = s->parser->parser_parse(s, avctx, (const uint8_t **) poutbuf,
164  poutbuf_size, buf, buf_size);
165  av_assert0(index > -0x20000000); // The API does not allow returning AVERROR codes
166 #define FILL(name) if(s->name > 0 && avctx->name <= 0) avctx->name = s->name
167  if (avctx->codec_type == AVMEDIA_TYPE_VIDEO) {
168  FILL(field_order);
169  }
170 
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  } else {
180  /* Don't return a pointer to dummy_buf. */
181  *poutbuf = NULL;
182  }
183  if (index < 0)
184  index = 0;
185  s->cur_offset += index;
186  return index;
187 }
188 
190 {
191  if (s) {
192  if (s->parser->parser_close)
193  s->parser->parser_close(s);
194  av_freep(&s->priv_data);
195  av_free(s);
196  }
197 }
198 
199 int ff_combine_frame(ParseContext *pc, int next,
200  const uint8_t **buf, int *buf_size)
201 {
202  if (pc->overread) {
203  ff_dlog(NULL, "overread %d, state:%"PRIX32" next:%d index:%d o_index:%d\n",
204  pc->overread, pc->state, next, pc->index, pc->overread_index);
205  ff_dlog(NULL, "%X %X %X %X\n",
206  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
207  }
208 
209  /* Copy overread bytes from last frame into buffer. */
210  for (; pc->overread > 0; pc->overread--)
211  pc->buffer[pc->index++] = pc->buffer[pc->overread_index++];
212 
213  if (next > *buf_size)
214  return AVERROR(EINVAL);
215 
216  /* flush remaining if EOF */
217  if (!*buf_size && next == END_NOT_FOUND)
218  next = 0;
219 
220  pc->last_index = pc->index;
221 
222  /* copy into buffer end return */
223  if (next == END_NOT_FOUND) {
224  void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
225  *buf_size + pc->index +
227 
228  if (!new_buffer) {
229  av_log(NULL, AV_LOG_ERROR, "Failed to reallocate parser buffer to %d\n", *buf_size + pc->index + AV_INPUT_BUFFER_PADDING_SIZE);
230  pc->index = 0;
231  return AVERROR(ENOMEM);
232  }
233  pc->buffer = new_buffer;
234  memcpy(&pc->buffer[pc->index], *buf, *buf_size);
235  pc->index += *buf_size;
236  return -1;
237  }
238 
239  av_assert0(next >= 0 || pc->buffer);
240 
241  *buf_size =
242  pc->overread_index = pc->index + next;
243 
244  /* append to buffer */
245  if (pc->index) {
246  void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
247  next + pc->index +
249  if (!new_buffer) {
250  av_log(NULL, AV_LOG_ERROR, "Failed to reallocate parser buffer to %d\n", next + pc->index + AV_INPUT_BUFFER_PADDING_SIZE);
251  pc->overread_index =
252  pc->index = 0;
253  return AVERROR(ENOMEM);
254  }
255  pc->buffer = new_buffer;
256  if (next > -AV_INPUT_BUFFER_PADDING_SIZE)
257  memcpy(&pc->buffer[pc->index], *buf,
259  pc->index = 0;
260  *buf = pc->buffer;
261  }
262 
263  if (next < -8) {
264  pc->overread += -8 - next;
265  next = -8;
266  }
267  /* store overread bytes */
268  for (; next < 0; next++) {
269  pc->state = pc->state << 8 | pc->buffer[pc->last_index + next];
270  pc->state64 = pc->state64 << 8 | pc->buffer[pc->last_index + next];
271  pc->overread++;
272  }
273 
274  if (pc->overread) {
275  ff_dlog(NULL, "overread %d, state:%"PRIX32" next:%d index:%d o_index:%d\n",
276  pc->overread, pc->state, next, pc->index, pc->overread_index);
277  ff_dlog(NULL, "%X %X %X %X\n",
278  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
279  }
280 
281  return 0;
282 }
283 
285 {
286  ParseContext *pc = s->priv_data;
287 
288  av_freep(&pc->buffer);
289 }
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:81
ParseContext::overread_index
int overread_index
the index into ParseContext.buffer of the overread bytes
Definition: parser.h:36
ff_parse_close
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:284
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:32
pts
static int64_t pts
Definition: transcode_aac.c:654
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:180
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:505
ParseContext::index
int index
Definition: parser.h:30
s
#define s(width, name)
Definition: cbs_vp9.c:256
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:372
AVCodecContext::codec_id
enum AVCodecID codec_id
Definition: avcodec.h:408
if
if(ret)
Definition: filter_design.txt:179
NULL
#define NULL
Definition: coverity.c:32
AV_PICTURE_TYPE_I
@ AV_PICTURE_TYPE_I
Intra.
Definition: avutil.h:274
index
int index
Definition: gxfenc.c:89
ff_dlog
#define ff_dlog(a,...)
Definition: tableprint_vlc.h:28
AVCodecParser::codec_ids
int codec_ids[7]
Definition: avcodec.h:2960
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:199
AV_CODEC_ID_NONE
@ AV_CODEC_ID_NONE
Definition: codec_id.h:48
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
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:2962
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:264
parser.h
AVCodecParserContext
Definition: avcodec.h:2800
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:2961
AV_INPUT_BUFFER_PADDING_SIZE
#define AV_INPUT_BUFFER_PADDING_SIZE
Definition: defs.h:40
AVCodecContext
main external API structure.
Definition: avcodec.h:398
PARSER_FLAG_FETCHED_OFFSET
#define PARSER_FLAG_FETCHED_OFFSET
Set if the parser has a valid file offset.
Definition: avcodec.h:2837
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:406
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:33
END_NOT_FOUND
#define END_NOT_FOUND
Definition: parser.h:40
AV_PARSER_PTS_NB
#define AV_PARSER_PTS_NB
Definition: avcodec.h:2827
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:34
AVCodecParser
Definition: avcodec.h:2959
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
av_parser_close
void av_parser_close(AVCodecParserContext *s)
Definition: parser.c:189