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
ff_h263_find_frame_end(ParseContext * pc,const uint8_t * buf,int buf_size)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
h263_parse(AVCodecParserContext * s,AVCodecContext * avctx,const uint8_t ** poutbuf,int * poutbuf_size,const uint8_t * buf,int buf_size)65 static int h263_parse(AVCodecParserContext *s,
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
73 if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
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
90 AVCodecParser ff_h263_parser = {
91 .codec_ids = { AV_CODEC_ID_H263 },
92 .priv_data_size = sizeof(ParseContext),
93 .parser_parse = h263_parse,
94 .parser_close = ff_parse_close,
95 };
96