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h263_parser.c
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1 /*
2  * H.263 parser
3  * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * H.263 parser
25  */
26 
27 #include "parser.h"
28 #include "h263_parser.h"
29 
30 int ff_h263_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size){
31  int vop_found, i;
32  uint32_t state;
33 
34  vop_found= pc->frame_start_found;
35  state= pc->state;
36 
37  i=0;
38  if(!vop_found){
39  for(i=0; i<buf_size; i++){
40  state= (state<<8) | buf[i];
41  if(state>>(32-22) == 0x20){
42  i++;
43  vop_found=1;
44  break;
45  }
46  }
47  }
48 
49  if(vop_found){
50  for(; i<buf_size; i++){
51  state= (state<<8) | buf[i];
52  if(state>>(32-22) == 0x20){
53  pc->frame_start_found=0;
54  pc->state=-1;
55  return i-3;
56  }
57  }
58  }
59  pc->frame_start_found= vop_found;
60  pc->state= state;
61 
62  return END_NOT_FOUND;
63 }
64 
66  AVCodecContext *avctx,
67  const uint8_t **poutbuf, int *poutbuf_size,
68  const uint8_t *buf, int buf_size)
69 {
70  ParseContext *pc = s->priv_data;
71  int next;
72 
74  next = buf_size;
75  } else {
76  next= ff_h263_find_frame_end(pc, buf, buf_size);
77 
78  if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
79  *poutbuf = NULL;
80  *poutbuf_size = 0;
81  return buf_size;
82  }
83  }
84 
85  *poutbuf = buf;
86  *poutbuf_size = buf_size;
87  return next;
88 }
89 
92  .priv_data_size = sizeof(ParseContext),
93  .parser_parse = h263_parse,
94  .parser_close = ff_parse_close,
95 };
#define NULL
Definition: coverity.c:32
const char * s
Definition: avisynth_c.h:768
int codec_ids[5]
Definition: avcodec.h:5122
int frame_start_found
Definition: parser.h:34
uint8_t
int ff_combine_frame(ParseContext *pc, int next, const uint8_t **buf, int *buf_size)
Combine the (truncated) bitstream to a complete frame.
Definition: parser.c:245
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:321
static int h263_parse(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition: h263_parser.c:65
main external API structure.
Definition: avcodec.h:1659
void * buf
Definition: avisynth_c.h:690
uint32_t state
contains the last few bytes in MSB order
Definition: parser.h:33
#define END_NOT_FOUND
Definition: parser.h:40
AVCodecParser ff_h263_parser
Definition: h263_parser.c:90
static struct @229 state
#define PARSER_FLAG_COMPLETE_FRAMES
Definition: avcodec.h:4988
int ff_h263_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
Definition: h263_parser.c:30