blob: 07a6b2bdc653235e5c5517076705276dab36f50f
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, AV_CODEC_ID_JPEGLS }, |
131 | .priv_data_size = sizeof(MJPEGParserContext), |
132 | .parser_parse = jpeg_parse, |
133 | .parser_close = ff_parse_close, |
134 | }; |
135 |