FFmpeg
mpeg4video_parser.c
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1 /*
2  * MPEG-4 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 #define UNCHECKED_BITSTREAM_READER 1
24 
25 #include "internal.h"
26 #include "parser.h"
27 #include "mpegvideo.h"
28 #include "mpeg4video.h"
29 #include "mpeg4video_parser.h"
30 
35 };
36 
37 int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
38 {
39  int vop_found, i;
40  uint32_t state;
41 
42  vop_found = pc->frame_start_found;
43  state = pc->state;
44 
45  i = 0;
46  if (!vop_found) {
47  for (i = 0; i < buf_size; i++) {
48  state = (state << 8) | buf[i];
49  if (state == VOP_STARTCODE) {
50  i++;
51  vop_found = 1;
52  break;
53  }
54  }
55  }
56 
57  if (vop_found) {
58  /* EOF considered as end of frame */
59  if (buf_size == 0)
60  return 0;
61  for (; i < buf_size; i++) {
62  state = (state << 8) | buf[i];
63  if ((state & 0xFFFFFF00) == 0x100) {
65  continue;
66  pc->frame_start_found = 0;
67  pc->state = -1;
68  return i - 3;
69  }
70  }
71  }
72  pc->frame_start_found = vop_found;
73  pc->state = state;
74  return END_NOT_FOUND;
75 }
76 
77 /* XXX: make it use less memory */
79  const uint8_t *buf, int buf_size)
80 {
81  struct Mp4vParseContext *pc = s1->priv_data;
82  Mpeg4DecContext *dec_ctx = &pc->dec_ctx;
83  MpegEncContext *s = &dec_ctx->m;
84  GetBitContext gb1, *gb = &gb1;
85  int ret;
86 
87  s->avctx = avctx;
88  s->current_picture_ptr = &s->current_picture;
89 
90  if (avctx->extradata_size && pc->first_picture) {
91  init_get_bits(gb, avctx->extradata, avctx->extradata_size * 8);
93  if (ret < 0)
94  av_log(avctx, AV_LOG_WARNING, "Failed to parse extradata\n");
95  }
96 
97  init_get_bits(gb, buf, 8 * buf_size);
99  if (s->width && (!avctx->width || !avctx->height ||
100  !avctx->coded_width || !avctx->coded_height)) {
101  ret = ff_set_dimensions(avctx, s->width, s->height);
102  if (ret < 0)
103  return ret;
104  }
105  if((s1->flags & PARSER_FLAG_USE_CODEC_TS) && s->avctx->time_base.den>0 && ret>=0){
106  av_assert1(s1->pts == AV_NOPTS_VALUE);
107  av_assert1(s1->dts == AV_NOPTS_VALUE);
108 
109  s1->pts = av_rescale_q(s->time, (AVRational){1, s->avctx->time_base.den}, (AVRational){1, 1200000});
110  }
111 
112  s1->pict_type = s->pict_type;
113  pc->first_picture = 0;
114  return ret;
115 }
116 
118 {
119  struct Mp4vParseContext *pc = s->priv_data;
120 
122 
123  pc->first_picture = 1;
124  pc->dec_ctx.m.quant_precision = 5;
125  pc->dec_ctx.m.slice_context_count = 1;
126  pc->dec_ctx.showed_packed_warning = 1;
127  return 0;
128 }
129 
131  AVCodecContext *avctx,
132  const uint8_t **poutbuf, int *poutbuf_size,
133  const uint8_t *buf, int buf_size)
134 {
135  ParseContext *pc = s->priv_data;
136  int next;
137 
138  if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
139  next = buf_size;
140  } else {
141  next = ff_mpeg4_find_frame_end(pc, buf, buf_size);
142 
143  if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
144  *poutbuf = NULL;
145  *poutbuf_size = 0;
146  return buf_size;
147  }
148  }
149  mpeg4_decode_header(s, avctx, buf, buf_size);
150 
151  *poutbuf = buf;
152  *poutbuf_size = buf_size;
153  return next;
154 }
155 
158  .priv_data_size = sizeof(struct Mp4vParseContext),
159  .parser_init = mpeg4video_parse_init,
160  .parser_parse = mpeg4video_parse,
161  .parser_close = ff_parse_close,
162 };
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:187
state
static struct @321 state
AV_CODEC_ID_MPEG4
@ AV_CODEC_ID_MPEG4
Definition: codec_id.h:61
ff_parse_close
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:282
internal.h
mpegvideo.h
ff_mpeg4videodec_static_init
void ff_mpeg4videodec_static_init(void)
Definition: mpeg4videodec.c:3377
ParseContext::state
uint32_t state
contains the last few bytes in MSB order
Definition: parser.h:33
init_get_bits
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:659
mpeg4video_parse
static int mpeg4video_parse(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition: mpeg4video_parser.c:130
ParseContext
Definition: parser.h:28
GetBitContext
Definition: get_bits.h:61
Mp4vParseContext::first_picture
int first_picture
Definition: mpeg4video_parser.c:34
AVCodecContext::coded_height
int coded_height
Definition: avcodec.h:689
av_cold
#define av_cold
Definition: attributes.h:90
AVCodecContext::extradata_size
int extradata_size
Definition: avcodec.h:603
s
#define s(width, name)
Definition: cbs_vp9.c:257
s1
#define s1
Definition: regdef.h:38
av_rescale_q
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
Rescale a 64-bit integer by 2 rational numbers.
Definition: mathematics.c:142
mpeg4_decode_header
static int mpeg4_decode_header(AVCodecParserContext *s1, AVCodecContext *avctx, const uint8_t *buf, int buf_size)
Definition: mpeg4video_parser.c:78
NULL
#define NULL
Definition: coverity.c:32
AVCodecParser::codec_ids
int codec_ids[5]
Definition: avcodec.h:3039
AVRational
Rational number (pair of numerator and denominator).
Definition: rational.h:58
ParseContext::frame_start_found
int frame_start_found
Definition: parser.h:34
Mpeg4DecContext
Definition: mpeg4video.h:74
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
ff_mpeg4_decode_picture_header
int ff_mpeg4_decode_picture_header(Mpeg4DecContext *ctx, GetBitContext *gb, int header)
Decode MPEG-4 headers.
Definition: mpeg4videodec.c:3221
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
EXT_STARTCODE
#define EXT_STARTCODE
Definition: mpeg4video.h:67
i
int i
Definition: input.c:407
PARSER_FLAG_COMPLETE_FRAMES
#define PARSER_FLAG_COMPLETE_FRAMES
Definition: avcodec.h:2913
mpeg4video_parse_init
static av_cold int mpeg4video_parse_init(AVCodecParserContext *s)
Definition: mpeg4video_parser.c:117
AVCodecContext::extradata
uint8_t * extradata
some codecs need / can use extradata like Huffman tables.
Definition: avcodec.h:602
av_assert1
#define av_assert1(cond)
assert() equivalent, that does not lie in speed critical code.
Definition: avassert.h:53
parser.h
AVCodecContext::height
int height
Definition: avcodec.h:674
Mp4vParseContext
Definition: mpeg4video_parser.c:31
Mp4vParseContext::dec_ctx
Mpeg4DecContext dec_ctx
Definition: mpeg4video_parser.c:33
AVCodecParserContext
Definition: avcodec.h:2879
ret
ret
Definition: filter_design.txt:187
AVCodecContext
main external API structure.
Definition: avcodec.h:501
ff_mpeg4video_parser
const AVCodecParser ff_mpeg4video_parser
Definition: mpeg4video_parser.c:156
mpeg4video.h
Mp4vParseContext::pc
ParseContext pc
Definition: mpeg4video_parser.c:32
PARSER_FLAG_USE_CODEC_TS
#define PARSER_FLAG_USE_CODEC_TS
Definition: avcodec.h:2917
VOP_STARTCODE
#define VOP_STARTCODE
Definition: mpeg4video.h:65
ff_mpeg4_find_frame_end
int ff_mpeg4_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
Find the end of the current frame in the bitstream.
Definition: mpeg4video_parser.c:37
AVCodecContext::coded_width
int coded_width
Bitstream width / height, may be different from width/height e.g.
Definition: avcodec.h:689
mpeg4video_parser.h
ff_set_dimensions
int ff_set_dimensions(AVCodecContext *s, int width, int height)
Check that the provided frame dimensions are valid and set them on the codec context.
Definition: utils.c:84
END_NOT_FOUND
#define END_NOT_FOUND
Definition: parser.h:40
AVCodecParser
Definition: avcodec.h:3038
AVCodecContext::width
int width
picture width / height.
Definition: avcodec.h:674
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
MpegEncContext
MpegEncContext.
Definition: mpegvideo.h:81
SLICE_STARTCODE
#define SLICE_STARTCODE
Definition: mpeg4video.h:66
dec_ctx
static AVCodecContext * dec_ctx
Definition: filtering_audio.c:43