text: /*
   * SubRip subtitle muxer
   * Copyright (c) 2012  Nicolas George <nicolas.george@normalesup.org>
   *
   * 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 "libavutil/log.h"
  #include "libavutil/intreadwrite.h"
  
  /* TODO: add options for:
     - character encoding;
     - LF / CRLF;
     - byte order mark.
   */
  
  typedef struct SRTContext{
      unsigned index;
  } SRTContext;
  
  static int srt_write_header(AVFormatContext *avf)
  {
      SRTContext *srt = avf->priv_data;
  
      if (avf->nb_streams != 1 ||
          avf->streams[0]->codecpar->codec_type != AVMEDIA_TYPE_SUBTITLE) {
          av_log(avf, AV_LOG_ERROR,
                 "SRT supports only a single subtitles stream.\n");
          return AVERROR(EINVAL);
      }
      if (avf->streams[0]->codecpar->codec_id != AV_CODEC_ID_TEXT &&
          avf->streams[0]->codecpar->codec_id != AV_CODEC_ID_SUBRIP) {
          av_log(avf, AV_LOG_ERROR,
                 "Unsupported subtitles codec: %s\n",
                 avcodec_get_name(avf->streams[0]->codecpar->codec_id));
          return AVERROR(EINVAL);
      }
      avpriv_set_pts_info(avf->streams[0], 64, 1, 1000);
      srt->index = 1;
      return 0;
  }
  
  static int srt_write_packet(AVFormatContext *avf, AVPacket *pkt)
  {
      SRTContext *srt = avf->priv_data;
  
      int64_t s = pkt->pts, e, d = pkt->duration;
      int size, x1 = -1, y1 = -1, x2 = -1, y2 = -1;
      const uint8_t *p;
  
      p = av_packet_get_side_data(pkt, AV_PKT_DATA_SUBTITLE_POSITION, &size);
      if (p && size == 16) {
          x1 = AV_RL32(p     );
          y1 = AV_RL32(p +  4);
          x2 = AV_RL32(p +  8);
          y2 = AV_RL32(p + 12);
      }
  
  #if FF_API_CONVERGENCE_DURATION
  FF_DISABLE_DEPRECATION_WARNINGS
      if (d <= 0)
          /* For backward compatibility, fallback to convergence_duration. */
          d = pkt->convergence_duration;
  FF_ENABLE_DEPRECATION_WARNINGS
  #endif
      if (s == AV_NOPTS_VALUE || d < 0) {
          av_log(avf, AV_LOG_WARNING,
                 "Insufficient timestamps in event number %d.\n", srt->index);
          return 0;
      }
      e = s + d;
      avio_printf(avf->pb, "%d\n%02d:%02d:%02d,%03d --> %02d:%02d:%02d,%03d",
                     srt->index,
                     (int)(s / 3600000),      (int)(s / 60000) % 60,
                     (int)(s /    1000) % 60, (int)(s %  1000),
                     (int)(e / 3600000),      (int)(e / 60000) % 60,
                     (int)(e /    1000) % 60, (int)(e %  1000));
      if (p)
          avio_printf(avf->pb, "  X1:%03d X2:%03d Y1:%03d Y2:%03d",
                      x1, x2, y1, y2);
      avio_printf(avf->pb, "\n");
  
      avio_write(avf->pb, pkt->data, pkt->size);
      avio_write(avf->pb, "\n\n", 2);
      srt->index++;
      return 0;
  }
  
  AVOutputFormat ff_srt_muxer = {
      .name           = "srt",
      .long_name      = NULL_IF_CONFIG_SMALL("SubRip subtitle"),
      .mime_type      = "application/x-subrip",
      .extensions     = "srt",
      .priv_data_size = sizeof(SRTContext),
      .write_header   = srt_write_header,
      .write_packet   = srt_write_packet,
      .flags          = AVFMT_VARIABLE_FPS | AVFMT_TS_NONSTRICT,
      .subtitle_codec = AV_CODEC_ID_SUBRIP,
  };
  