2 * RAW H.261 video demuxer
3 * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
5 * This file is part of FFmpeg.
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.
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.
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
22 #include "libavcodec/get_bits.h"
26 static int h261_probe(AVProbeData
*p
)
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;
42 if(gn
!= next_gn
) invalid_psc
++;
46 static const int lut
[16]={1,2,3,4,5,6,7,8,9,10,11,12,0,16,16,16};
49 static const int lut
[16]={1,3,16,5,16,0,16,16,16,16,16,16,16,16,16,16};
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;
62 FF_DEF_RAWVIDEO_DEMUXER(h261
, "raw H.261", h261_probe
, "h261", AV_CODEC_ID_H261
)