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- /*
- * RAW H.261 video demuxer
- * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
- *
- * This file is part of Libav.
- *
- * Libav 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.
- *
- * Libav 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 Libav; 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 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)
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