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ffmpeg-4.2.2/libavformat/dvbsub.c 2.15 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * RAW dvbsub demuxer
   * Copyright (c) 2015 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 "libavutil/intreadwrite.h"
  
  #include "avformat.h"
  #include "rawdec.h"
  
  
  static int dvbsub_probe(const AVProbeData *p)
  {
      int i, j, k;
      const uint8_t *end = p->buf + p->buf_size;
      int type, len;
      int max_score = 0;
  
      for(i=0; i<p->buf_size; i++){
          if (p->buf[i] == 0x0f) {
              const uint8_t *ptr = p->buf + i;
              uint8_t histogram[6] = {0};
              int min = 255;
              for(j=0; 6 < end - ptr; j++) {
                  if (*ptr != 0x0f)
                      break;
                  type    = ptr[1];
                  //page_id = AV_RB16(ptr + 2);
                  len     = AV_RB16(ptr + 4);
                  if (type == 0x80) {
                      ;
                  } else if (type >= 0x10 && type <= 0x14) {
                      histogram[type - 0x10] ++;
                  } else
                      break;
                  if (6 + len > end - ptr)
                      break;
                  ptr += 6 + len;
              }
              for (k=0; k < 4; k++) {
                  min = FFMIN(min, histogram[k]);
              }
              if (min && j > max_score)
                  max_score = j;
          }
      }
  
      if (max_score > 5)
          return AVPROBE_SCORE_EXTENSION;
  
      return 0;
  }
  
  FF_DEF_RAWSUB_DEMUXER(dvbsub, "raw dvbsub", dvbsub_probe, NULL, AV_CODEC_ID_DVB_SUBTITLE, AVFMT_GENERIC_INDEX)