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
ff_h263_find_frame_end(ParseContext * pc,const uint8_t * buf,int buf_size)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
72 static int h263_parse(AVCodecParserContext *s,
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
101 const AVCodecParser ff_h263_parser = {
102 .codec_ids = { AV_CODEC_ID_H263 },
103 .priv_data_size = sizeof(ParseContext),
104 .parser_parse = h263_parse,
105 .parser_close = ff_parse_close,
106 };
107