text: /*
   * NC camera feed demuxer
   * Copyright (c) 2009  Nicolas Martin (martinic at iro dot umontreal dot ca)
   *                     Edouard Auvinet
   *
   * 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 "internal.h"
  
  #define NC_VIDEO_FLAG 0x1A5
  
  static int nc_probe(AVProbeData *probe_packet)
  {
      int size;
  
      if (AV_RB32(probe_packet->buf) != NC_VIDEO_FLAG)
          return 0;
  
      size = AV_RL16(probe_packet->buf + 5);
  
      if (size + 20 > probe_packet->buf_size)
          return AVPROBE_SCORE_MAX/4;
  
      if (AV_RB32(probe_packet->buf+16+size) == NC_VIDEO_FLAG)
          return AVPROBE_SCORE_MAX;
  
      return 0;
  }
  
  static int nc_read_header(AVFormatContext *s)
  {
      AVStream *st = avformat_new_stream(s, NULL);
  
      if (!st)
          return AVERROR(ENOMEM);
  
      st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
      st->codec->codec_id   = AV_CODEC_ID_MPEG4;
      st->need_parsing      = AVSTREAM_PARSE_FULL;
  
      avpriv_set_pts_info(st, 64, 1, 100);
  
      return 0;
  }
  
  static int nc_read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      int size;
      int ret;
  
      uint32_t state=-1;
      while (state != NC_VIDEO_FLAG) {
          if (avio_feof(s->pb))
              return AVERROR(EIO);
          state = (state<<8) + avio_r8(s->pb);
      }
  
      avio_r8(s->pb);
      size = avio_rl16(s->pb);
      avio_skip(s->pb, 9);
  
      if (size == 0) {
          av_log(s, AV_LOG_DEBUG, "Next packet size is zero\n");
          return AVERROR(EAGAIN);
      }
  
      ret = av_get_packet(s->pb, pkt, size);
      if (ret != size) {
          if (ret > 0) av_free_packet(pkt);
          return AVERROR(EIO);
      }
  
      pkt->stream_index = 0;
      return size;
  }
  
  AVInputFormat ff_nc_demuxer = {
      .name           = "nc",
      .long_name      = NULL_IF_CONFIG_SMALL("NC camera feed"),
      .read_probe     = nc_probe,
      .read_header    = nc_read_header,
      .read_packet    = nc_read_packet,
      .extensions     = "v",
  };
  