/* * 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(const AVProbeData *p) { int i; int valid_psc=0; int invalid_psc=0; int next_gn=0; int src_fmt=0; for(i=0; i<p->buf_size; i++){ if ((AV_RB16(&p->buf[i]) - 1) < 0xFFU) { int shift = av_log2_16bit(p->buf[i+1]); uint32_t code = AV_RB64(&p->buf[FFMAX(i-1, 0)]) >> (24+shift); 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 static const int lut[16]={1,2,3,4,5,6,7,8,9,10,11,12,0,16,16,16}; next_gn = lut[gn]; }else{ //QCIF static const int lut[16]={1,3,16,5,16,0,16,16,16,16,16,16,16,16,16,16}; next_gn = lut[gn]; } } } } if(valid_psc > 2*invalid_psc + 6){ return AVPROBE_SCORE_EXTENSION; }else if(valid_psc > 2*invalid_psc + 2) return AVPROBE_SCORE_EXTENSION / 2; return 0; } FF_DEF_RAWVIDEO_DEMUXER(h261, "raw H.261", h261_probe, "h261", AV_CODEC_ID_H261)