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  1. /*
  2.  * NC camera feed demuxer
  3.  * Copyright (c) 2009  Nicolas Martin (martinic at iro dot umontreal dot ca)
  4.  *                     Edouard Auvinet
  5.  *
  6.  * This file is part of FFmpeg.
  7.  *
  8.  * FFmpeg is free software; you can redistribute it and/or
  9.  * modify it under the terms of the GNU Lesser General Public
  10.  * License as published by the Free Software Foundation; either
  11.  * version 2.1 of the License, or (at your option) any later version.
  12.  *
  13.  * FFmpeg is distributed in the hope that it will be useful,
  14.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16.  * Lesser General Public License for more details.
  17.  *
  18.  * You should have received a copy of the GNU Lesser General Public
  19.  * License along with FFmpeg; if not, write to the Free Software
  20.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21.  */
  22.  
  23. #include "libavutil/intreadwrite.h"
  24. #include "avformat.h"
  25. #include "internal.h"
  26.  
  27. #define NC_VIDEO_FLAG 0x1A5
  28.  
  29. static int nc_probe(AVProbeData *probe_packet)
  30. {
  31.     int size;
  32.  
  33.     if (AV_RB32(probe_packet->buf) != NC_VIDEO_FLAG)
  34.         return 0;
  35.  
  36.     size = AV_RL16(probe_packet->buf + 5);
  37.  
  38.     if (size + 20 > probe_packet->buf_size)
  39.         return AVPROBE_SCORE_MAX/4;
  40.  
  41.     if (AV_RB32(probe_packet->buf+16+size) == NC_VIDEO_FLAG)
  42.         return AVPROBE_SCORE_MAX;
  43.  
  44.     return 0;
  45. }
  46.  
  47. static int nc_read_header(AVFormatContext *s)
  48. {
  49.     AVStream *st = avformat_new_stream(s, NULL);
  50.  
  51.     if (!st)
  52.         return AVERROR(ENOMEM);
  53.  
  54.     st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
  55.     st->codec->codec_id   = AV_CODEC_ID_MPEG4;
  56.     st->need_parsing      = AVSTREAM_PARSE_FULL;
  57.  
  58.     avpriv_set_pts_info(st, 64, 1, 100);
  59.  
  60.     return 0;
  61. }
  62.  
  63. static int nc_read_packet(AVFormatContext *s, AVPacket *pkt)
  64. {
  65.     int size;
  66.     int ret;
  67.  
  68.     uint32_t state=-1;
  69.     while (state != NC_VIDEO_FLAG) {
  70.         if (url_feof(s->pb))
  71.             return AVERROR(EIO);
  72.         state = (state<<8) + avio_r8(s->pb);
  73.     }
  74.  
  75.     avio_r8(s->pb);
  76.     size = avio_rl16(s->pb);
  77.     avio_skip(s->pb, 9);
  78.  
  79.     if (size == 0) {
  80.         av_log(s, AV_LOG_DEBUG, "Next packet size is zero\n");
  81.         return AVERROR(EAGAIN);
  82.     }
  83.  
  84.     ret = av_get_packet(s->pb, pkt, size);
  85.     if (ret != size) {
  86.         if (ret > 0) av_free_packet(pkt);
  87.         return AVERROR(EIO);
  88.     }
  89.  
  90.     pkt->stream_index = 0;
  91.     return size;
  92. }
  93.  
  94. AVInputFormat ff_nc_demuxer = {
  95.     .name           = "nc",
  96.     .long_name      = NULL_IF_CONFIG_SMALL("NC camera feed"),
  97.     .read_probe     = nc_probe,
  98.     .read_header    = nc_read_header,
  99.     .read_packet    = nc_read_packet,
  100.     .extensions     = "v",
  101. };
  102.