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
31typedef 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 */
40static 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
102static 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
129AVCodecParser 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};
135