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2ba45a60 DM |
1 | /* |
2 | * MJPEG parser | |
3 | * Copyright (c) 2000, 2001 Fabrice Bellard | |
4 | * Copyright (c) 2003 Alex Beregszaszi | |
5 | * Copyright (c) 2003-2004 Michael Niedermayer | |
6 | * | |
7 | * This file is part of FFmpeg. | |
8 | * | |
9 | * FFmpeg is free software; you can redistribute it and/or | |
10 | * modify it under the terms of the GNU Lesser General Public | |
11 | * License as published by the Free Software Foundation; either | |
12 | * version 2.1 of the License, or (at your option) any later version. | |
13 | * | |
14 | * FFmpeg is distributed in the hope that it will be useful, | |
15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
17 | * Lesser General Public License for more details. | |
18 | * | |
19 | * You should have received a copy of the GNU Lesser General Public | |
20 | * License along with FFmpeg; if not, write to the Free Software | |
21 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
22 | */ | |
23 | ||
24 | /** | |
25 | * @file | |
26 | * MJPEG parser. | |
27 | */ | |
28 | ||
29 | #include "parser.h" | |
30 | ||
31 | typedef struct MJPEGParserContext{ | |
32 | ParseContext pc; | |
33 | int size; | |
34 | }MJPEGParserContext; | |
35 | ||
36 | /** | |
37 | * Find the end of the current frame in the bitstream. | |
38 | * @return the position of the first byte of the next frame, or -1 | |
39 | */ | |
40 | static int find_frame_end(MJPEGParserContext *m, const uint8_t *buf, int buf_size){ | |
41 | ParseContext *pc= &m->pc; | |
42 | int vop_found, i; | |
43 | uint32_t state; | |
44 | ||
45 | vop_found= pc->frame_start_found; | |
46 | state= pc->state; | |
47 | ||
48 | i=0; | |
49 | if(!vop_found){ | |
50 | for(i=0; i<buf_size;){ | |
51 | state= (state<<8) | buf[i]; | |
52 | if(state>=0xFFC00000 && state<=0xFFFEFFFF){ | |
53 | if(state>=0xFFD80000 && state<=0xFFD8FFFF){ | |
54 | i++; | |
55 | vop_found=1; | |
56 | break; | |
57 | }else if(state<0xFFD00000 || state>0xFFD9FFFF){ | |
58 | m->size= (state&0xFFFF)-1; | |
59 | } | |
60 | } | |
61 | if(m->size>0){ | |
62 | int size= FFMIN(buf_size-i, m->size); | |
63 | i+=size; | |
64 | m->size-=size; | |
65 | state=0; | |
66 | continue; | |
67 | }else | |
68 | i++; | |
69 | } | |
70 | } | |
71 | ||
72 | if(vop_found){ | |
73 | /* EOF considered as end of frame */ | |
74 | if (buf_size == 0) | |
75 | return 0; | |
76 | for(; i<buf_size;){ | |
77 | state= (state<<8) | buf[i]; | |
78 | if(state>=0xFFC00000 && state<=0xFFFEFFFF){ | |
79 | if(state>=0xFFD80000 && state<=0xFFD8FFFF){ | |
80 | pc->frame_start_found=0; | |
81 | pc->state=0; | |
82 | return i-3; | |
83 | } else if(state<0xFFD00000 || state>0xFFD9FFFF){ | |
84 | m->size= (state&0xFFFF)-1; | |
85 | } | |
86 | } | |
87 | if(m->size>0){ | |
88 | int size= FFMIN(buf_size-i, m->size); | |
89 | i+=size; | |
90 | m->size-=size; | |
91 | state=0; | |
92 | continue; | |
93 | }else | |
94 | i++; | |
95 | } | |
96 | } | |
97 | pc->frame_start_found= vop_found; | |
98 | pc->state= state; | |
99 | return END_NOT_FOUND; | |
100 | } | |
101 | ||
102 | static int jpeg_parse(AVCodecParserContext *s, | |
103 | AVCodecContext *avctx, | |
104 | const uint8_t **poutbuf, int *poutbuf_size, | |
105 | const uint8_t *buf, int buf_size) | |
106 | { | |
107 | MJPEGParserContext *m = s->priv_data; | |
108 | ParseContext *pc = &m->pc; | |
109 | int next; | |
110 | ||
111 | if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){ | |
112 | next= buf_size; | |
113 | }else{ | |
114 | next= find_frame_end(m, buf, buf_size); | |
115 | ||
116 | if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { | |
117 | *poutbuf = NULL; | |
118 | *poutbuf_size = 0; | |
119 | return buf_size; | |
120 | } | |
121 | } | |
122 | ||
123 | *poutbuf = buf; | |
124 | *poutbuf_size = buf_size; | |
125 | return next; | |
126 | } | |
127 | ||
128 | ||
129 | AVCodecParser ff_mjpeg_parser = { | |
130 | .codec_ids = { AV_CODEC_ID_MJPEG }, | |
131 | .priv_data_size = sizeof(MJPEGParserContext), | |
132 | .parser_parse = jpeg_parse, | |
133 | .parser_close = ff_parse_close, | |
134 | }; |