libavformat/dvbsub.c

   1 /*
   2  * RAW dvbsub demuxer
   3  * Copyright (c) 2015 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 "libavutil/intreadwrite.h"
  23
  24 #include "avformat.h"
  25 #include "rawdec.h"
  26
  27
  28 static int dvbsub_probe(const AVProbeData *p)
  29 {
  30     int i, j, k;
  31     const uint8_t *end = p->buf + p->buf_size;
  32     int type, len;
  33     int max_score = 0;
  34
  35     for(i=0; i<p->buf_size; i++){
  36         if (p->buf[i] == 0x0f) {
  37             const uint8_t *ptr = p->buf + i;
  38             uint8_t histogram[6] = {0};
  39             int min = 255;
  40             for(j=0; 6 < end - ptr; j++) {
  41                 if (*ptr != 0x0f)
  42                     break;
  43                 type    = ptr[1];
  44                 //page_id = AV_RB16(ptr + 2);
  45                 len     = AV_RB16(ptr + 4);
  46                 if (type == 0x80) {
  47                     ;
  48                 } else if (type >= 0x10 && type <= 0x14) {
  49                     histogram[type - 0x10] ++;
  50                 } else
  51                     break;
  52                 if (6 + len > end - ptr)
  53                     break;
  54                 ptr += 6 + len;
  55             }
  56             for (k=0; k < 4; k++) {
  57                 min = FFMIN(min, histogram[k]);
  58             }
  59             if (min && j > max_score)
  60                 max_score = j;
  61         }
  62     }
  63
  64     if (max_score > 5)
  65         return AVPROBE_SCORE_EXTENSION;
  66
  67     return 0;
  68 }
  69
  70 FF_DEF_RAWSUB_DEMUXER(dvbsub, "raw dvbsub", dvbsub_probe, NULL, AV_CODEC_ID_DVB_SUBTITLE, AVFMT_GENERIC_INDEX)