/src/ffmpeg/libavformat/h261dec.c
Line | Count | Source |
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 "libavutil/intreadwrite.h" |
23 | | #include "avformat.h" |
24 | | #include "rawdec.h" |
25 | | |
26 | | static int h261_probe(const AVProbeData *p) |
27 | 967k | { |
28 | 967k | int i; |
29 | 967k | int valid_psc=0; |
30 | 967k | int invalid_psc=0; |
31 | 967k | int next_gn=0; |
32 | 967k | int src_fmt=0; |
33 | | |
34 | 3.31G | for(i=0; i<p->buf_size; i++){ |
35 | 3.31G | if ((AV_RB16(&p->buf[i]) - 1) < 0xFFU) { |
36 | 243M | int shift = av_log2_16bit(p->buf[i+1]); |
37 | 243M | uint32_t code = AV_RB64(&p->buf[FFMAX(i-1, 0)]) >> (24+shift); |
38 | 243M | if ((code & 0xffff0000) == 0x10000) { |
39 | 147M | int gn= (code>>12)&0xf; |
40 | 147M | if(!gn) |
41 | 37.1M | src_fmt= code&8; |
42 | 147M | if(gn != next_gn) invalid_psc++; |
43 | 3.51M | else valid_psc++; |
44 | | |
45 | 147M | if(src_fmt){ // CIF |
46 | 34.7M | static const int lut[16]={1,2,3,4,5,6,7,8,9,10,11,12,0,16,16,16}; |
47 | 34.7M | next_gn = lut[gn]; |
48 | 113M | }else{ //QCIF |
49 | 113M | static const int lut[16]={1,3,16,5,16,0,16,16,16,16,16,16,16,16,16,16}; |
50 | 113M | next_gn = lut[gn]; |
51 | 113M | } |
52 | 147M | } |
53 | 243M | } |
54 | 3.31G | } |
55 | 967k | if(valid_psc > 2*invalid_psc + 6){ |
56 | 125 | return AVPROBE_SCORE_EXTENSION; |
57 | 967k | }else if(valid_psc > 2*invalid_psc + 2) |
58 | 248 | return AVPROBE_SCORE_EXTENSION / 2; |
59 | 967k | return 0; |
60 | 967k | } |
61 | | |
62 | | FF_DEF_RAWVIDEO_DEMUXER(h261, "raw H.261", h261_probe, "h261", AV_CODEC_ID_H261) |