1/* 2 * RAW H.261 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 "libavcodec/get_bits.h" 23#include "avformat.h" 24#include "rawdec.h" 25 26static int h261_probe(AVProbeData *p) 27{ 28 uint32_t code= -1; 29 int i; 30 int valid_psc=0; 31 int invalid_psc=0; 32 int next_gn=0; 33 int src_fmt=0; 34 GetBitContext gb; 35 36 init_get_bits(&gb, p->buf, p->buf_size*8); 37 38 for(i=0; i<p->buf_size*8; i++){ 39 if ((code & 0x01ff0000) || !(code & 0xff00)) { 40 code = (code<<8) + get_bits(&gb, 8); 41 i += 7; 42 } else 43 code = (code<<1) + get_bits1(&gb); 44 if ((code & 0xffff0000) == 0x10000) { 45 int gn= (code>>12)&0xf; 46 if(!gn) 47 src_fmt= code&8; 48 if(gn != next_gn) invalid_psc++; 49 else valid_psc++; 50 51 if(src_fmt){ // CIF 52 next_gn= (gn+1 )%13; 53 }else{ //QCIF 54 next_gn= (gn+1+!!gn)% 7; 55 } 56 } 57 } 58 if(valid_psc > 2*invalid_psc + 6){ 59 return 50; 60 }else if(valid_psc > 2*invalid_psc + 2) 61 return 25; 62 return 0; 63} 64 65FF_DEF_RAWVIDEO_DEMUXER(h261, "raw H.261", h261_probe, "h261", CODEC_ID_H261) 66