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FFmpeg/libavformat/h264dec.c

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  1. /*

  2.  * RAW H.264 video demuxer

  3.  * Copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>

  4.  *

  5.  * This file is part of Libav.

  6.  *

  7.  * Libav 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.  * Libav 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 Libav; if not, write to the Free Software

  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  20.  */

  21. 

  22. #include "avformat.h"

  23. #include "rawdec.h"

  24. 

  25. static int h264_probe(AVProbeData *p)

  26. {

  27.     uint32_t code = -1;

  28.     int sps = 0, pps = 0, idr = 0, res = 0, sli = 0;

  29.     int i;

  30. 

  31.     for (i = 0; i < p->buf_size; i++) {

  32.         code = (code << 8) + p->buf[i];

  33.         if ((code & 0xffffff00) == 0x100) {

  34.             int ref_idc = (code >> 5) & 3;

  35.             int type    = code & 0x1F;

  36.             static const int8_t ref_zero[] = {

  37.                  2,  0,  0,  0,  0, -1,  1, -1,

  38.                 -1,  1,  1,  1,  1, -1,  2,  2,

  39.                  2,  2,  2,  0,  2,  2,  2,  2,

  40.                  2,  2,  2,  2,  2,  2,  2,  2

  41.             };

  42. 

  43.             if (code & 0x80) // forbidden_bit

  44.                 return 0;

  45. 

  46.             if (ref_zero[type] == 1 && ref_idc)

  47.                 return 0;

  48.             if (ref_zero[type] == -1 && !ref_idc)

  49.                 return 0;

  50.             if (ref_zero[type] == 2)

  51.                 res++;

  52. 

  53.             switch (type) {

  54.             case 1:

  55.                 sli++;

  56.                 break;

  57.             case 5:

  58.                 idr++;

  59.                 break;

  60.             case 7:

  61.                 if (p->buf[i + 2] & 0x03)

  62.                     return 0;

  63.                 sps++;

  64.                 break;

  65.             case 8:

  66.                 pps++;

  67.                 break;

  68.             }

  69.         }

  70.     }

  71. 

  72.     if (sps && pps && (idr || sli > 3) && res < (sps + pps + idr))

  73.         return AVPROBE_SCORE_EXTENSION + 1;  // 1 more than .mpg

  74. 

  75.     return 0;

  76. }

  77. 

  78. FF_DEF_RAWVIDEO_DEMUXER(h264, "raw H.264 video", h264_probe, "h26l,h264,264,avc", AV_CODEC_ID_H264)