text: /*
   * SSA/ASS muxer
   * Copyright (c) 2008 Michael Niedermayer
   *
   * 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"
  
  typedef struct ASSContext{
      unsigned int extra_index;
  }ASSContext;
  
  static int write_header(AVFormatContext *s)
  {
      ASSContext *ass = s->priv_data;
      AVCodecContext *avctx= s->streams[0]->codec;
      uint8_t *last= NULL;
  
      if(s->nb_streams != 1 || avctx->codec_id != CODEC_ID_SSA){
          av_log(s, AV_LOG_ERROR, "Exactly one ASS/SSA stream is needed.\n");
          return -1;
      }
  
      while(ass->extra_index < avctx->extradata_size){
          uint8_t *p  = avctx->extradata + ass->extra_index;
          uint8_t *end= strchr(p, '\n');
          if(!end) end= avctx->extradata + avctx->extradata_size;
          else     end++;
  
          put_buffer(s->pb, p, end-p);
          ass->extra_index += end-p;
  
          if(last && !memcmp(last, "[Events]", 8))
              break;
          last=p;
      }
  
      put_flush_packet(s->pb);
  
      return 0;
  }
  
  static int write_packet(AVFormatContext *s, AVPacket *pkt)
  {
      put_buffer(s->pb, pkt->data, pkt->size);
  
      put_flush_packet(s->pb);
  
      return 0;
  }
  
  static int write_trailer(AVFormatContext *s)
  {
      ASSContext *ass = s->priv_data;
      AVCodecContext *avctx= s->streams[0]->codec;
  
      put_buffer(s->pb, avctx->extradata      + ass->extra_index,
                        avctx->extradata_size - ass->extra_index);
  
      put_flush_packet(s->pb);
  
      return 0;
  }
  
  AVOutputFormat ass_muxer = {
      "ass",
      NULL_IF_CONFIG_SMALL("SSA/ASS format"),
      NULL,
      "ass,ssa",
      sizeof(ASSContext),
      CODEC_ID_NONE,
      CODEC_ID_NONE,
      write_header,
      write_packet,
      write_trailer,
      .flags = AVFMT_GLOBALHEADER | AVFMT_NOTIMESTAMPS
  };
  