1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
|
/*
* MJPEG parser
* Copyright (c) 2000, 2001 Fabrice Bellard
* Copyright (c) 2003 Alex Beregszaszi
* Copyright (c) 2003-2004 Michael Niedermayer
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* MJPEG parser.
*/
#include "parser.h"
typedef struct MJPEGParserContext{
ParseContext pc;
int size;
}MJPEGParserContext;
/**
* Find the end of the current frame in the bitstream.
* @return the position of the first byte of the next frame, or -1
*/
static int find_frame_end(MJPEGParserContext *m, const uint8_t *buf, int buf_size){
ParseContext *pc= &m->pc;
int vop_found, i;
uint32_t state;
vop_found= pc->frame_start_found;
state= pc->state;
i=0;
if(!vop_found){
for(i=0; i<buf_size;){
state= (state<<8) | buf[i];
if(state>=0xFFC00000 && state<=0xFFFEFFFF){
if(state>=0xFFD80000 && state<=0xFFD8FFFF){
i++;
vop_found=1;
break;
}else if(state<0xFFD00000 || state>0xFFD9FFFF){
m->size= (state&0xFFFF)-1;
}
}
if(m->size>0){
int size= FFMIN(buf_size-i, m->size);
i+=size;
m->size-=size;
state=0;
continue;
}else
i++;
}
}
if(vop_found){
/* EOF considered as end of frame */
if (buf_size == 0)
return 0;
for(; i<buf_size;){
state= (state<<8) | buf[i];
if(state>=0xFFC00000 && state<=0xFFFEFFFF){
if(state>=0xFFD80000 && state<=0xFFD8FFFF){
pc->frame_start_found=0;
pc->state=0;
return i-3;
} else if(state<0xFFD00000 || state>0xFFD9FFFF){
m->size= (state&0xFFFF)-1;
}
}
if(m->size>0){
int size= FFMIN(buf_size-i, m->size);
i+=size;
m->size-=size;
state=0;
continue;
}else
i++;
}
}
pc->frame_start_found= vop_found;
pc->state= state;
return END_NOT_FOUND;
}
static int jpeg_parse(AVCodecParserContext *s,
AVCodecContext *avctx,
const uint8_t **poutbuf, int *poutbuf_size,
const uint8_t *buf, int buf_size)
{
MJPEGParserContext *m = s->priv_data;
ParseContext *pc = &m->pc;
int next;
if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
next= buf_size;
}else{
next= find_frame_end(m, buf, buf_size);
if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
*poutbuf = NULL;
*poutbuf_size = 0;
return buf_size;
}
}
*poutbuf = buf;
*poutbuf_size = buf_size;
return next;
}
AVCodecParser ff_mjpeg_parser = {
.codec_ids = { CODEC_ID_MJPEG },
.priv_data_size = sizeof(MJPEGParserContext),
.parser_parse = jpeg_parse,
.parser_close = ff_parse_close,
};
|
