libavformat/h264dec.c

   1 /*
   2  * RAW H.264 video demuxer
   3  * Copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg 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  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include "libavcodec/get_bits.h"
  23 #include "libavcodec/golomb.h"
  24 #include "avformat.h"
  25 #include "rawdec.h"
  26
  27 #define MAX_SPS_COUNT          32
  28 #define MAX_PPS_COUNT         256
  29
  30 static int h264_probe(const AVProbeData *p)
  31 {
  32     uint32_t code = -1;
  33     int sps = 0, pps = 0, idr = 0, res = 0, sli = 0;
  34     int i, ret;
  35     int pps_ids[MAX_PPS_COUNT+1] = {0};
  36     int sps_ids[MAX_SPS_COUNT+1] = {0};
  37     unsigned pps_id, sps_id;
  38     GetBitContext gb;
  39
  40     for (i = 0; i + 2 < p->buf_size; i++) {
  41         code = (code << 8) + p->buf[i];
  42         if ((code & 0xffffff00) == 0x100) {
  43             int ref_idc = (code >> 5) & 3;
  44             int type    = code & 0x1F;
  45             static const int8_t ref_zero[] = {
  46                  2,  0,  0,  0,  0, -1,  1, -1,
  47                 -1,  1,  1,  1,  1, -1,  2,  2,
  48                  2,  2,  2,  0,  2,  2,  2,  2,
  49                  2,  2,  2,  2,  2,  2,  2,  2
  50             };
  51
  52             if (code & 0x80) // forbidden_bit
  53                 return 0;
  54
  55             if (ref_zero[type] == 1 && ref_idc)
  56                 return 0;
  57             if (ref_zero[type] == -1 && !ref_idc)
  58                 return 0;
  59             if (ref_zero[type] == 2) {
  60                 if (!(code == 0x100 && !p->buf[i + 1] && !p->buf[i + 2]))
  61                     res++;
  62             }
  63
  64             ret = init_get_bits8(&gb, p->buf + i + 1, p->buf_size - i - 1);
  65             if (ret < 0)
  66                 return 0;
  67
  68             switch (type) {
  69             case 1:
  70             case 5:
  71                 get_ue_golomb_long(&gb);
  72                 if (get_ue_golomb_long(&gb) > 9U)
  73                     return 0;
  74                 pps_id = get_ue_golomb_long(&gb);
  75                 if (pps_id > MAX_PPS_COUNT)
  76                     return 0;
  77                 if (!pps_ids[pps_id])
  78                     break;
  79
  80                 if (type == 1)
  81                     sli++;
  82                 else
  83                     idr++;
  84                 break;
  85             case 7:
  86                 skip_bits(&gb, 14);
  87                 if (get_bits(&gb, 2))
  88                     return 0;
  89                 skip_bits(&gb, 8);
  90                 sps_id = get_ue_golomb_long(&gb);
  91                 if (sps_id > MAX_SPS_COUNT)
  92                     return 0;
  93                 sps_ids[sps_id] = 1;
  94                 sps++;
  95                 break;
  96             case 8:
  97                 pps_id = get_ue_golomb_long(&gb);
  98                 if (pps_id > MAX_PPS_COUNT)
  99                     return 0;
 100                 sps_id = get_ue_golomb_long(&gb);
 101                 if (sps_id > MAX_SPS_COUNT)
 102                     return 0;
 103                 if (!sps_ids[sps_id])
 104                     break;
 105                 pps_ids[pps_id] = 1;
 106                 pps++;
 107                 break;
 108             }
 109         }
 110     }
 111     ff_tlog(NULL, "sps:%d pps:%d idr:%d sli:%d res:%d\n", sps, pps, idr, sli, res);
 112
 113     if (sps && pps && (idr || sli > 3) && res < (sps + pps + idr))
 114         return AVPROBE_SCORE_EXTENSION + 1;  // 1 more than .mpg
 115
 116     return 0;
 117 }
 118
 119 FF_DEF_RAWVIDEO_DEMUXER(h264, "raw H.264 video", h264_probe, "h26l,h264,264,avc", AV_CODEC_ID_H264)