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ffmpeg-4.2.2/libavcodec/realtextdec.c 2.68 KB
aac5773f   hucm   功能基本完成,接口待打磨
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  /*
   * Copyright (c) 2012 Clément Bœsch
   *
   * 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
   */
  
  /**
   * @file
   * RealText subtitle decoder
   * @see http://service.real.com/help/library/guides/ProductionGuide/prodguide/htmfiles/realtext.htm
   */
  
  #include "avcodec.h"
  #include "ass.h"
  #include "libavutil/avstring.h"
  #include "libavutil/bprint.h"
  
  static int rt_event_to_ass(AVBPrint *buf, const char *p)
  {
      int prev_chr_is_space = 1;
  
      while (*p) {
          if (*p != '<') {
              if (!av_isspace(*p))
                  av_bprint_chars(buf, *p, 1);
              else if (!prev_chr_is_space)
                  av_bprint_chars(buf, ' ', 1);
              prev_chr_is_space = av_isspace(*p);
          } else {
              const char *end = strchr(p, '>');
              if (!end)
                  break;
              if (!av_strncasecmp(p, "<br/>", 5) ||
                  !av_strncasecmp(p, "<br>",  4)) {
                  av_bprintf(buf, "\\N");
              }
              p = end;
          }
          p++;
      }
      return 0;
  }
  
  static int realtext_decode_frame(AVCodecContext *avctx,
                                   void *data, int *got_sub_ptr, AVPacket *avpkt)
  {
      int ret = 0;
      AVSubtitle *sub = data;
      const char *ptr = avpkt->data;
      FFASSDecoderContext *s = avctx->priv_data;
      AVBPrint buf;
  
      av_bprint_init(&buf, 0, 4096);
      if (ptr && avpkt->size > 0 && !rt_event_to_ass(&buf, ptr))
          ret = ff_ass_add_rect(sub, buf.str, s->readorder++, 0, NULL, NULL);
      av_bprint_finalize(&buf, NULL);
      if (ret < 0)
          return ret;
      *got_sub_ptr = sub->num_rects > 0;
      return avpkt->size;
  }
  
  AVCodec ff_realtext_decoder = {
      .name           = "realtext",
      .long_name      = NULL_IF_CONFIG_SMALL("RealText subtitle"),
      .type           = AVMEDIA_TYPE_SUBTITLE,
      .id             = AV_CODEC_ID_REALTEXT,
      .decode         = realtext_decode_frame,
      .init           = ff_ass_subtitle_header_default,
      .flush          = ff_ass_decoder_flush,
      .priv_data_size = sizeof(FFASSDecoderContext),
  };