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2ba45a60 DM |
1 | /* |
2 | * RAW H.261 video demuxer | |
3 | * Copyright (c) 2009 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 | #include "libavcodec/get_bits.h" | |
23 | #include "avformat.h" | |
24 | #include "rawdec.h" | |
25 | ||
26 | static int h261_probe(AVProbeData *p) | |
27 | { | |
28 | int i; | |
29 | int valid_psc=0; | |
30 | int invalid_psc=0; | |
31 | int next_gn=0; | |
32 | int src_fmt=0; | |
33 | ||
34 | for(i=0; i<p->buf_size; i++){ | |
35 | if ((AV_RB16(&p->buf[i]) - 1) < 0xFFU) { | |
36 | int shift = av_log2_16bit(p->buf[i+1]); | |
37 | uint32_t code = AV_RB64(&p->buf[FFMAX(i-1, 0)]) >> (24+shift); | |
38 | if ((code & 0xffff0000) == 0x10000) { | |
39 | int gn= (code>>12)&0xf; | |
40 | if(!gn) | |
41 | src_fmt= code&8; | |
42 | if(gn != next_gn) invalid_psc++; | |
43 | else valid_psc++; | |
44 | ||
45 | if(src_fmt){ // CIF | |
46 | static const int lut[16]={1,2,3,4,5,6,7,8,9,10,11,12,0,16,16,16}; | |
47 | next_gn = lut[gn]; | |
48 | }else{ //QCIF | |
49 | static const int lut[16]={1,3,16,5,16,0,16,16,16,16,16,16,16,16,16,16}; | |
50 | next_gn = lut[gn]; | |
51 | } | |
52 | } | |
53 | } | |
54 | } | |
55 | if(valid_psc > 2*invalid_psc + 6){ | |
56 | return AVPROBE_SCORE_EXTENSION; | |
57 | }else if(valid_psc > 2*invalid_psc + 2) | |
58 | return AVPROBE_SCORE_EXTENSION / 2; | |
59 | return 0; | |
60 | } | |
61 | ||
62 | FF_DEF_RAWVIDEO_DEMUXER(h261, "raw H.261", h261_probe, "h261", AV_CODEC_ID_H261) |