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 */
find_frame_end(MJPEGParserContext * m,const uint8_t * buf,int buf_size)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>=0xFFD8FFC0 && 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>=0xFFD8FFC0 && 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 if (m->size >= 0xF000)
86 m->size = 0;
87 }
88 }
89 if(m->size>0){
90 int size= FFMIN(buf_size-i, m->size);
91 i+=size;
92 m->size-=size;
93 state=0;
94 continue;
95 }else
96 i++;
97 }
98 }
99 pc->frame_start_found= vop_found;
100 pc->state= state;
101 return END_NOT_FOUND;
102 }
103
jpeg_parse(AVCodecParserContext * s,AVCodecContext * avctx,const uint8_t ** poutbuf,int * poutbuf_size,const uint8_t * buf,int buf_size)104 static int jpeg_parse(AVCodecParserContext *s,
105 AVCodecContext *avctx,
106 const uint8_t **poutbuf, int *poutbuf_size,
107 const uint8_t *buf, int buf_size)
108 {
109 MJPEGParserContext *m = s->priv_data;
110 ParseContext *pc = &m->pc;
111 int next;
112
113 if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){
114 next= buf_size;
115 }else{
116 next= find_frame_end(m, buf, buf_size);
117
118 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
119 *poutbuf = NULL;
120 *poutbuf_size = 0;
121 return buf_size;
122 }
123 }
124
125 *poutbuf = buf;
126 *poutbuf_size = buf_size;
127 return next;
128 }
129
130
131 AVCodecParser ff_mjpeg_parser = {
132 .codec_ids = { AV_CODEC_ID_MJPEG, AV_CODEC_ID_JPEGLS },
133 .priv_data_size = sizeof(MJPEGParserContext),
134 .parser_parse = jpeg_parse,
135 .parser_close = ff_parse_close,
136 };
137