FFmpeg
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 #if FF_API_FLAG_TRUNCATED
29 /* Nuke this header when removing FF_API_FLAG_TRUNCATED */
30 #include "h263_parser.h"
31 
32 int ff_h263_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size){
33 #else
34 
35 static int h263_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
36 {
37 #endif
38  int vop_found, i;
39  uint32_t state;
40 
41  vop_found= pc->frame_start_found;
42  state= pc->state;
43 
44  i=0;
45  if(!vop_found){
46  for(i=0; i<buf_size; i++){
47  state= (state<<8) | buf[i];
48  if(state>>(32-22) == 0x20){
49  i++;
50  vop_found=1;
51  break;
52  }
53  }
54  }
55 
56  if(vop_found){
57  for(; i<buf_size; i++){
58  state= (state<<8) | buf[i];
59  if(state>>(32-22) == 0x20){
60  pc->frame_start_found=0;
61  pc->state=-1;
62  return i-3;
63  }
64  }
65  }
66  pc->frame_start_found= vop_found;
67  pc->state= state;
68 
69  return END_NOT_FOUND;
70 }
71 
73  AVCodecContext *avctx,
74  const uint8_t **poutbuf, int *poutbuf_size,
75  const uint8_t *buf, int buf_size)
76 {
77  ParseContext *pc = s->priv_data;
78  int next;
79 
80  if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
81  next = buf_size;
82  } else {
83 #if FF_API_FLAG_TRUNCATED
84  next= ff_h263_find_frame_end(pc, buf, buf_size);
85 #else
86  next = h263_find_frame_end(pc, buf, buf_size);
87 #endif
88 
89  if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
90  *poutbuf = NULL;
91  *poutbuf_size = 0;
92  return buf_size;
93  }
94  }
95 
96  *poutbuf = buf;
97  *poutbuf_size = buf_size;
98  return next;
99 }
100 
103  .priv_data_size = sizeof(ParseContext),
104  .parser_parse = h263_parse,
105  .parser_close = ff_parse_close,
106 };
ff_parse_close
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:284
ff_h263_parser
const AVCodecParser ff_h263_parser
Definition: h263_parser.c:101
ParseContext::state
uint32_t state
contains the last few bytes in MSB order
Definition: parser.h:33
ParseContext
Definition: parser.h:28
ff_h263_find_frame_end
int ff_h263_find_frame_end(ParseContext *pc, const uint8_t *buf, int buf_size)
Definition: h263_parser.c:32
s
#define s(width, name)
Definition: cbs_vp9.c:256
NULL
#define NULL
Definition: coverity.c:32
h263_parse
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:72
ParseContext::frame_start_found
int frame_start_found
Definition: parser.h:34
AVCodecParser::codec_ids
int codec_ids[7]
Definition: avcodec.h:2950
AV_CODEC_ID_H263
@ AV_CODEC_ID_H263
Definition: codec_id.h:54
ff_combine_frame
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:199
PARSER_FLAG_COMPLETE_FRAMES
#define PARSER_FLAG_COMPLETE_FRAMES
Definition: avcodec.h:2824
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:271
parser.h
h263_parser.h
AVCodecParserContext
Definition: avcodec.h:2790
AVCodecContext
main external API structure.
Definition: avcodec.h:389
state
static struct @326 state
END_NOT_FOUND
#define END_NOT_FOUND
Definition: parser.h:40
AVCodecParser
Definition: avcodec.h:2949