1/*
2 * RAW H.263 video demuxer
3 * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#include "avformat.h"
23#include "rawdec.h"
24
25static int h263_probe(AVProbeData *p)
26{
27    uint64_t code= -1;
28    int i;
29    int valid_psc=0;
30    int invalid_psc=0;
31    int res_change=0;
32    int src_fmt, last_src_fmt=-1;
33    int last_gn=0;
34
35    for(i=0; i<p->buf_size; i++){
36        code = (code<<8) + p->buf[i];
37        if ((code & 0xfffffc0000) == 0x800000) {
38            src_fmt= (code>>2)&3;
39            if(   src_fmt != last_src_fmt
40               && last_src_fmt>0 && last_src_fmt<6
41               && src_fmt<6)
42                res_change++;
43
44            if((code&0x300)==0x200 && src_fmt){
45                valid_psc++;
46                last_gn=0;
47            }else
48                invalid_psc++;
49            last_src_fmt= src_fmt;
50        } else if((code & 0xffff800000) == 0x800000) {
51            int gn= (code>>(23-5)) & 0x1F;
52            if(gn<last_gn){
53                invalid_psc++;
54            }else
55                last_gn= gn;
56        }
57    }
58//av_log(NULL, AV_LOG_ERROR, "h263_probe: psc:%d invalid:%d res_change:%d\n", valid_psc, invalid_psc, res_change);
59//h263_probe: psc:3 invalid:0 res_change:0 (1588/recent_ffmpeg_parses_mpg_incorrectly.mpg)
60    if(valid_psc > 2*invalid_psc + 2*res_change + 3){
61        return 50;
62    }else if(valid_psc > 2*invalid_psc)
63        return 25;
64    return 0;
65}
66
67FF_DEF_RAWVIDEO_DEMUXER(h263, "raw H.263", h263_probe, NULL, CODEC_ID_H263)
68