text: /*
   * MicroDVD subtitle demuxer
   * Copyright (c) 2010  Aurelien Jacobs <aurel@gnuage.org>
   * Copyright (c) 2012  Clément Bœsch <u pkh me>
   *
   * 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 "avformat.h"
  #include "internal.h"
  #include "subtitles.h"
  #include "libavutil/intreadwrite.h"
  #include "libavutil/opt.h"
  
  #define MAX_LINESIZE 2048
  
  
  typedef struct {
      const AVClass *class;
      FFDemuxSubtitlesQueue q;
      AVRational frame_rate;
  } MicroDVDContext;
  
  
  static int microdvd_probe(AVProbeData *p)
  {
      unsigned char c;
      const uint8_t *ptr = p->buf;
      int i;
  
      if (AV_RB24(ptr) == 0xEFBBBF)
          ptr += 3;  /* skip UTF-8 BOM */
  
      for (i=0; i<3; i++) {
          if (sscanf(ptr, "{%*d}{}%c",     &c) != 1 &&
              sscanf(ptr, "{%*d}{%*d}%c",  &c) != 1 &&
              sscanf(ptr, "{DEFAULT}{}%c", &c) != 1)
              return 0;
          ptr += ff_subtitles_next_line(ptr);
      }
      return AVPROBE_SCORE_MAX;
  }
  
  static int64_t get_pts(const char *buf)
  {
      int frame;
      char c;
  
      if (sscanf(buf, "{%d}{%c", &frame, &c) == 2)
          return frame;
      return AV_NOPTS_VALUE;
  }
  
  static int get_duration(const char *buf)
  {
      int frame_start, frame_end;
  
      if (sscanf(buf, "{%d}{%d}", &frame_start, &frame_end) == 2)
          return frame_end - frame_start;
      return -1;
  }
  
  static const char *bom = "\xEF\xBB\xBF";
  
  static int microdvd_read_header(AVFormatContext *s)
  {
      AVRational pts_info = (AVRational){ 2997, 125 };  /* default: 23.976 fps */
      MicroDVDContext *microdvd = s->priv_data;
      AVStream *st = avformat_new_stream(s, NULL);
      int i = 0;
      char line_buf[MAX_LINESIZE];
      int has_real_fps = 0;
  
      if (!st)
          return AVERROR(ENOMEM);
  
      while (!avio_feof(s->pb)) {
          char *p;
          AVPacket *sub;
          int64_t pos = avio_tell(s->pb);
          int len = ff_get_line(s->pb, line_buf, sizeof(line_buf));
          char *line = line_buf;
  
          if (!strncmp(line, bom, 3))
              line += 3;
          p = line;
  
          if (!len)
              break;
          line[strcspn(line, "\r\n")] = 0;
          if (i++ < 3) {
              int frame;
              double fps;
              char c;
  
              if ((sscanf(line, "{%d}{}%6lf",    &frame, &fps) == 2 ||
                   sscanf(line, "{%d}{%*d}%6lf", &frame, &fps) == 2)
                  && frame <= 1 && fps > 3 && fps < 100) {
                  pts_info = av_d2q(fps, 100000);
                  has_real_fps = 1;
              }
              if (!st->codec->extradata && sscanf(line, "{DEFAULT}{}%c", &c) == 1) {
                  st->codec->extradata = av_strdup(line + 11);
                  if (!st->codec->extradata)
                      return AVERROR(ENOMEM);
                  st->codec->extradata_size = strlen(st->codec->extradata) + 1;
                  continue;
              }
          }
  #define SKIP_FRAME_ID                                       \
      p = strchr(p, '}');                                     \
      if (!p) {                                               \
          av_log(s, AV_LOG_WARNING, "Invalid event \"%s\""    \
                 " at line %d\n", line, i);                   \
          continue;                                           \
      }                                                       \
      p++
          SKIP_FRAME_ID;
          SKIP_FRAME_ID;
          if (!*p)
              continue;
          sub = ff_subtitles_queue_insert(&microdvd->q, p, strlen(p), 0);
          if (!sub)
              return AVERROR(ENOMEM);
          sub->pos = pos;
          sub->pts = get_pts(line);
          sub->duration = get_duration(line);
      }
      ff_subtitles_queue_finalize(&microdvd->q);
      if (has_real_fps) {
          /* export the FPS info only if set in the file */
          microdvd->frame_rate = pts_info;
      } else if (microdvd->frame_rate.num) {
          /* fallback on user specified frame rate */
          pts_info = microdvd->frame_rate;
      }
      avpriv_set_pts_info(st, 64, pts_info.den, pts_info.num);
      st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
      st->codec->codec_id   = AV_CODEC_ID_MICRODVD;
      return 0;
  }
  
  static int microdvd_read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      MicroDVDContext *microdvd = s->priv_data;
      return ff_subtitles_queue_read_packet(&microdvd->q, pkt);
  }
  
  static int microdvd_read_seek(AVFormatContext *s, int stream_index,
                               int64_t min_ts, int64_t ts, int64_t max_ts, int flags)
  {
      MicroDVDContext *microdvd = s->priv_data;
      return ff_subtitles_queue_seek(&microdvd->q, s, stream_index,
                                     min_ts, ts, max_ts, flags);
  }
  
  static int microdvd_read_close(AVFormatContext *s)
  {
      MicroDVDContext *microdvd = s->priv_data;
      ff_subtitles_queue_clean(&microdvd->q);
      return 0;
  }
  
  
  #define OFFSET(x) offsetof(MicroDVDContext, x)
  #define SD AV_OPT_FLAG_SUBTITLE_PARAM|AV_OPT_FLAG_DECODING_PARAM
  static const AVOption microdvd_options[] = {
      { "subfps", "set the movie frame rate fallback", OFFSET(frame_rate), AV_OPT_TYPE_RATIONAL, {.dbl=0}, 0, INT_MAX, SD },
      { NULL }
  };
  
  static const AVClass microdvd_class = {
      .class_name = "microdvddec",
      .item_name  = av_default_item_name,
      .option     = microdvd_options,
      .version    = LIBAVUTIL_VERSION_INT,
  };
  
  AVInputFormat ff_microdvd_demuxer = {
      .name           = "microdvd",
      .long_name      = NULL_IF_CONFIG_SMALL("MicroDVD subtitle format"),
      .priv_data_size = sizeof(MicroDVDContext),
      .read_probe     = microdvd_probe,
      .read_header    = microdvd_read_header,
      .read_packet    = microdvd_read_packet,
      .read_seek2     = microdvd_read_seek,
      .read_close     = microdvd_read_close,
      .priv_class     = &microdvd_class,
  };
  