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  parser->codec_ids[5] == codec_id ||
51  parser->codec_ids[6] == codec_id)
52  goto found;
53  }
54  return NULL;
55 
56 found:
58  if (!s)
59  goto err_out;
60  s->parser = parser;
61  s->priv_data = av_mallocz(parser->priv_data_size);
62  if (!s->priv_data)
63  goto err_out;
64  s->fetch_timestamp=1;
65  s->pict_type = AV_PICTURE_TYPE_I;
66  if (parser->parser_init) {
67  ret = parser->parser_init(s);
68  if (ret != 0)
69  goto err_out;
70  }
71  s->key_frame = -1;
72  s->dts_sync_point = INT_MIN;
73  s->dts_ref_dts_delta = INT_MIN;
74  s->pts_dts_delta = INT_MIN;
75  s->format = -1;
76 
77  return s;
78 
79 err_out:
80  if (s)
81  av_freep(&s->priv_data);
82  av_free(s);
83  return NULL;
84 }
85 
86 void ff_fetch_timestamp(AVCodecParserContext *s, int off, int remove, int fuzzy)
87 {
88  int i;
89 
90  if (!fuzzy) {
91  s->dts =
92  s->pts = AV_NOPTS_VALUE;
93  s->pos = -1;
94  s->offset = 0;
95  }
96  for (i = 0; i < AV_PARSER_PTS_NB; i++) {
97  if (s->cur_offset + off >= s->cur_frame_offset[i] &&
98  (s->frame_offset < s->cur_frame_offset[i] ||
99  (!s->frame_offset && !s->next_frame_offset)) && // first field/frame
100  // check disabled since MPEG-TS does not send complete PES packets
101  /*s->next_frame_offset + off <*/ s->cur_frame_end[i]){
102 
103  if (!fuzzy || s->cur_frame_dts[i] != AV_NOPTS_VALUE) {
104  s->dts = s->cur_frame_dts[i];
105  s->pts = s->cur_frame_pts[i];
106  s->pos = s->cur_frame_pos[i];
107  s->offset = s->next_frame_offset - s->cur_frame_offset[i];
108  }
109  if (remove)
110  s->cur_frame_offset[i] = INT64_MAX;
111  if (s->cur_offset + off < s->cur_frame_end[i])
112  break;
113  }
114  }
115 }
116 
118  uint8_t **poutbuf, int *poutbuf_size,
119  const uint8_t *buf, int buf_size,
120  int64_t pts, int64_t dts, int64_t pos)
121 {
122  int index, i;
123  uint8_t dummy_buf[AV_INPUT_BUFFER_PADDING_SIZE];
124 
126 
127  /* Parsers only work for the specified codec ids. */
128  av_assert1(avctx->codec_id == s->parser->codec_ids[0] ||
129  avctx->codec_id == s->parser->codec_ids[1] ||
130  avctx->codec_id == s->parser->codec_ids[2] ||
131  avctx->codec_id == s->parser->codec_ids[3] ||
132  avctx->codec_id == s->parser->codec_ids[4] ||
133  avctx->codec_id == s->parser->codec_ids[5] ||
134  avctx->codec_id == s->parser->codec_ids[6]);
135 
136  if (!(s->flags & PARSER_FLAG_FETCHED_OFFSET)) {
137  s->next_frame_offset =
138  s->cur_offset = pos;
139  s->flags |= PARSER_FLAG_FETCHED_OFFSET;
140  }
141 
142  if (buf_size == 0) {
143  /* padding is always necessary even if EOF, so we add it here */
144  memset(dummy_buf, 0, sizeof(dummy_buf));
145  buf = dummy_buf;
146  } else if (s->cur_offset + buf_size != s->cur_frame_end[s->cur_frame_start_index]) { /* skip remainder packets */
147  /* add a new packet descriptor */
148  i = (s->cur_frame_start_index + 1) & (AV_PARSER_PTS_NB - 1);
149  s->cur_frame_start_index = i;
150  s->cur_frame_offset[i] = s->cur_offset;
151  s->cur_frame_end[i] = s->cur_offset + buf_size;
152  s->cur_frame_pts[i] = pts;
153  s->cur_frame_dts[i] = dts;
154  s->cur_frame_pos[i] = pos;
155  }
156 
157  if (s->fetch_timestamp) {
158  s->fetch_timestamp = 0;
159  s->last_pts = s->pts;
160  s->last_dts = s->dts;
161  s->last_pos = s->pos;
162  ff_fetch_timestamp(s, 0, 0, 0);
163  }
164  /* WARNING: the returned index can be negative */
165  index = s->parser->parser_parse(s, avctx, (const uint8_t **) poutbuf,
166  poutbuf_size, buf, buf_size);
167  av_assert0(index > -0x20000000); // The API does not allow returning AVERROR codes
168 #define FILL(name) if(s->name > 0 && avctx->name <= 0) avctx->name = s->name
169  if (avctx->codec_type == AVMEDIA_TYPE_VIDEO) {
170  FILL(field_order);
171  }
172 
173  /* update the file pointer */
174  if (*poutbuf_size) {
175  /* fill the data for the current frame */
176  s->frame_offset = s->next_frame_offset;
177 
178  /* offset of the next frame */
179  s->next_frame_offset = s->cur_offset + index;
180  s->fetch_timestamp = 1;
181  } else {
182  /* Don't return a pointer to dummy_buf. */
183  *poutbuf = NULL;
184  }
185  if (index < 0)
186  index = 0;
187  s->cur_offset += index;
188  return index;
189 }
190 
192 {
193  if (s) {
194  if (s->parser->parser_close)
195  s->parser->parser_close(s);
196  av_freep(&s->priv_data);
197  av_free(s);
198  }
199 }
200 
201 int ff_combine_frame(ParseContext *pc, int next,
202  const uint8_t **buf, int *buf_size)
203 {
204  if (pc->overread) {
205  ff_dlog(NULL, "overread %d, state:%"PRIX32" next:%d index:%d o_index:%d\n",
206  pc->overread, pc->state, next, pc->index, pc->overread_index);
207  ff_dlog(NULL, "%X %X %X %X\n",
208  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
209  }
210 
211  /* Copy overread bytes from last frame into buffer. */
212  for (; pc->overread > 0; pc->overread--)
213  pc->buffer[pc->index++] = pc->buffer[pc->overread_index++];
214 
215  if (next > *buf_size)
216  return AVERROR(EINVAL);
217 
218  /* flush remaining if EOF */
219  if (!*buf_size && next == END_NOT_FOUND)
220  next = 0;
221 
222  pc->last_index = pc->index;
223 
224  /* copy into buffer end return */
225  if (next == END_NOT_FOUND) {
226  void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
227  *buf_size + pc->index +
229 
230  if (!new_buffer) {
231  av_log(NULL, AV_LOG_ERROR, "Failed to reallocate parser buffer to %d\n", *buf_size + pc->index + AV_INPUT_BUFFER_PADDING_SIZE);
232  pc->index = 0;
233  return AVERROR(ENOMEM);
234  }
235  pc->buffer = new_buffer;
236  memcpy(&pc->buffer[pc->index], *buf, *buf_size);
237  pc->index += *buf_size;
238  return -1;
239  }
240 
241  av_assert0(next >= 0 || pc->buffer);
242 
243  *buf_size =
244  pc->overread_index = pc->index + next;
245 
246  /* append to buffer */
247  if (pc->index) {
248  void *new_buffer = av_fast_realloc(pc->buffer, &pc->buffer_size,
249  next + pc->index +
251  if (!new_buffer) {
252  av_log(NULL, AV_LOG_ERROR, "Failed to reallocate parser buffer to %d\n", next + pc->index + AV_INPUT_BUFFER_PADDING_SIZE);
253  pc->overread_index =
254  pc->index = 0;
255  return AVERROR(ENOMEM);
256  }
257  pc->buffer = new_buffer;
258  if (next > -AV_INPUT_BUFFER_PADDING_SIZE)
259  memcpy(&pc->buffer[pc->index], *buf,
261  pc->index = 0;
262  *buf = pc->buffer;
263  }
264 
265  if (next < -8) {
266  pc->overread += -8 - next;
267  next = -8;
268  }
269  /* store overread bytes */
270  for (; next < 0; next++) {
271  pc->state = pc->state << 8 | pc->buffer[pc->last_index + next];
272  pc->state64 = pc->state64 << 8 | pc->buffer[pc->last_index + next];
273  pc->overread++;
274  }
275 
276  if (pc->overread) {
277  ff_dlog(NULL, "overread %d, state:%"PRIX32" next:%d index:%d o_index:%d\n",
278  pc->overread, pc->state, next, pc->index, pc->overread_index);
279  ff_dlog(NULL, "%X %X %X %X\n",
280  (*buf)[0], (*buf)[1], (*buf)[2], (*buf)[3]);
281  }
282 
283  return 0;
284 }
285 
287 {
288  ParseContext *pc = s->priv_data;
289 
290  av_freep(&pc->buffer);
291 }
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:286
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:86
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:653
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:504
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:393
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
ff_dlog
#define ff_dlog(a,...)
Definition: tableprint_vlc.h:29
AVCodecParser::codec_ids
int codec_ids[7]
Definition: avcodec.h:2935
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:201
i
int i
Definition: input.c:406
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:2937
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:263
parser.h
AVCodecParserContext
Definition: avcodec.h:2775
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:2936
AV_INPUT_BUFFER_PADDING_SIZE
#define AV_INPUT_BUFFER_PADDING_SIZE
Definition: defs.h:40
AVCodecContext
main external API structure.
Definition: avcodec.h:383
PARSER_FLAG_FETCHED_OFFSET
#define PARSER_FLAG_FETCHED_OFFSET
Set if the parser has a valid file offset.
Definition: avcodec.h:2812
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:391
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:117
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:2802
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
AVCodecParser
Definition: avcodec.h:2934
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
av_parser_close
void av_parser_close(AVCodecParserContext *s)
Definition: parser.c:191