ffmpeg/libavformat/h264dec.c

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/*
* RAW H.264 video demuxer
* Copyright (c) 2008 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 "avformat.h"
#include "rawdec.h"
static int h264_probe(AVProbeData *p)
{
uint32_t code = -1;
int sps = 0, pps = 0, idr = 0, res = 0, sli = 0;
int i;
for (i = 0; i < p->buf_size; i++) {
code = (code << 8) + p->buf[i];
if ((code & 0xffffff00) == 0x100) {
int ref_idc = (code >> 5) & 3;
int type = code & 0x1F;
static const int8_t ref_zero[] = {
2, 0, 0, 0, 0, -1, 1, -1,
-1, 1, 1, 1, 1, -1, 2, 2,
2, 2, 2, 0, 2, 2, 2, 2,
2, 2, 2, 2, 2, 2, 2, 2
};
if (code & 0x80) // forbidden_bit
return 0;
if (ref_zero[type] == 1 && ref_idc)
return 0;
if (ref_zero[type] == -1 && !ref_idc)
return 0;
if (ref_zero[type] == 2)
res++;
switch (type) {
case 1:
sli++;
break;
case 5:
idr++;
break;
case 7:
if (p->buf[i + 2] & 0x03)
return 0;
sps++;
break;
case 8:
pps++;
break;
}
}
}
if (sps && pps && (idr || sli > 3) && res < (sps + pps + idr))
return AVPROBE_SCORE_EXTENSION + 1; // 1 more than .mpg
return 0;
}
FF_DEF_RAWVIDEO_DEMUXER(h264, "raw H.264 video", h264_probe, "h26l,h264,264,avc", AV_CODEC_ID_H264)