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
30int 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
65static 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    next= ff_h263_find_frame_end(pc, buf, buf_size);
74
75    if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
76        *poutbuf = NULL;
77        *poutbuf_size = 0;
78        return buf_size;
79    }
80
81    *poutbuf = buf;
82    *poutbuf_size = buf_size;
83    return next;
84}
85
86AVCodecParser h263_parser = {
87    { CODEC_ID_H263 },
88    sizeof(ParseContext),
89    NULL,
90    h263_parse,
91    ff_parse_close,
92};
93