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 26static 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 62FF_DEF_RAWVIDEO_DEMUXER(h261, "raw H.261", h261_probe, "h261", AV_CODEC_ID_H261) 63