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ffmpeg / libavformat / h264dec.c @ 2912e87a

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/*
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 * RAW H.264 video demuxer
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 * Copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
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 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * Libav is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include "avformat.h"
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#include "rawdec.h"
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static int h264_probe(AVProbeData *p)
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{
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    uint32_t code= -1;
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    int sps=0, pps=0, idr=0, res=0, sli=0;
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    int i;
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    for(i=0; i<p->buf_size; i++){
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        code = (code<<8) + p->buf[i];
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        if ((code & 0xffffff00) == 0x100) {
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            int ref_idc= (code>>5)&3;
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            int type   = code & 0x1F;
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            static const int8_t ref_zero[32]={
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                2, 0, 0, 0, 0,-1, 1,-1,
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               -1, 1, 1, 1, 1,-1, 2, 2,
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                2, 2, 2, 0, 2, 2, 2, 2,
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                2, 2, 2, 2, 2, 2, 2, 2
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            };
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            if(code & 0x80) //forbidden bit
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                return 0;
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            if(ref_zero[type] == 1 && ref_idc)
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                return 0;
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            if(ref_zero[type] ==-1 && !ref_idc)
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                return 0;
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            if(ref_zero[type] == 2)
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                res++;
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            switch(type){
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            case     1:   sli++; break;
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            case     5:   idr++; break;
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            case     7:
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                if(p->buf[i+2]&0x0F)
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                    return 0;
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                sps++;
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                break;
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            case     8:   pps++; break;
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            }
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        }
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    }
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    if(sps && pps && (idr||sli>3) && res<(sps+pps+idr))
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        return AVPROBE_SCORE_MAX/2+1; // +1 for .mpg
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    return 0;
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}
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AVInputFormat ff_h264_demuxer = {
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    "h264",
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    NULL_IF_CONFIG_SMALL("raw H.264 video format"),
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    0,
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    h264_probe,
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    ff_raw_video_read_header,
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    ff_raw_read_partial_packet,
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    .flags= AVFMT_GENERIC_INDEX,
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    .extensions = "h26l,h264,264", //FIXME remove after writing mpeg4_probe
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    .value = CODEC_ID_H264,
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};