mjpeg_parser.c
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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 Libav.
8  *
9  * Libav 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  * Libav 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 Libav; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
29 #include "parser.h"
30 
31 
36 static int find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size){
37  int vop_found, i;
38  uint16_t state;
39 
40  vop_found= pc->frame_start_found;
41  state= pc->state;
42 
43  i=0;
44  if(!vop_found){
45  for(i=0; i<buf_size; i++){
46  state= (state<<8) | buf[i];
47  if(state == 0xFFD8){
48  i++;
49  vop_found=1;
50  break;
51  }
52  }
53  }
54 
55  if(vop_found){
56  /* EOF considered as end of frame */
57  if (buf_size == 0)
58  return 0;
59  for(; i<buf_size; i++){
60  state= (state<<8) | buf[i];
61  if(state == 0xFFD8){
62  pc->frame_start_found=0;
63  pc->state=0;
64  return i-1;
65  }
66  }
67  }
68  pc->frame_start_found= vop_found;
69  pc->state= state;
70  return END_NOT_FOUND;
71 }
72 
74  AVCodecContext *avctx,
75  const uint8_t **poutbuf, int *poutbuf_size,
76  const uint8_t *buf, int buf_size)
77 {
78  ParseContext *pc = s->priv_data;
79  int next;
80 
82  next= buf_size;
83  }else{
84  next= find_frame_end(pc, buf, buf_size);
85 
86  if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
87  *poutbuf = NULL;
88  *poutbuf_size = 0;
89  return buf_size;
90  }
91  }
92 
93  *poutbuf = buf;
94  *poutbuf_size = buf_size;
95  return next;
96 }
97 
98 
100  .codec_ids = { CODEC_ID_MJPEG },
101  .priv_data_size = sizeof(ParseContext),
102  .parser_parse = jpeg_parse,
103  .parser_close = ff_parse_close,
104 };