| /* |
| * RAW H.261 video demuxer |
| * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at> |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #include "libavcodec/get_bits.h" |
| #include "avformat.h" |
| #include "rawdec.h" |
| |
| static int h261_probe(AVProbeData *p) |
| { |
| uint32_t code= -1; |
| int i; |
| int valid_psc=0; |
| int invalid_psc=0; |
| int next_gn=0; |
| int src_fmt=0; |
| GetBitContext gb; |
| |
| init_get_bits(&gb, p->buf, p->buf_size*8); |
| |
| for(i=0; i<p->buf_size*8; i++){ |
| if ((code & 0x01ff0000) || !(code & 0xff00)) { |
| code = (code<<8) + get_bits(&gb, 8); |
| i += 7; |
| } else |
| code = (code<<1) + get_bits1(&gb); |
| if ((code & 0xffff0000) == 0x10000) { |
| int gn= (code>>12)&0xf; |
| if(!gn) |
| src_fmt= code&8; |
| if(gn != next_gn) invalid_psc++; |
| else valid_psc++; |
| |
| if(src_fmt){ // CIF |
| next_gn= (gn+1 )%13; |
| }else{ //QCIF |
| next_gn= (gn+1+!!gn)% 7; |
| } |
| } |
| } |
| if(valid_psc > 2*invalid_psc + 6){ |
| return 50; |
| }else if(valid_psc > 2*invalid_psc + 2) |
| return 25; |
| return 0; |
| } |
| |
| FF_DEF_RAWVIDEO_DEMUXER(h261, "raw H.261", h261_probe, "h261", CODEC_ID_H261) |
