libavformat/ncdec.c

   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
  26 #define NC_VIDEO_FLAG 0x1A5
  27
  28 static int nc_probe(AVProbeData *probe_packet)
  29 {
  30     int size;
  31
  32     if (AV_RB32(probe_packet->buf) != NC_VIDEO_FLAG)
  33         return 0;
  34
  35     size = AV_RL16(probe_packet->buf + 5);
  36
  37     if (size + 20 > probe_packet->buf_size)
  38         return 3*AVPROBE_SCORE_MAX/2;
  39
  40     if (AV_RB32(probe_packet->buf+16+size) == NC_VIDEO_FLAG)
  41         return AVPROBE_SCORE_MAX;
  42
  43     return 0;
  44 }
  45
  46 static int nc_read_header(AVFormatContext *s, AVFormatParameters *ap)
  47 {
  48     AVStream *st = av_new_stream(s, 0);
  49
  50     if (!st)
  51         return AVERROR(ENOMEM);
  52
  53     st->codec->codec_type = CODEC_TYPE_VIDEO;
  54     st->codec->codec_id   = CODEC_ID_MPEG4;
  55     st->need_parsing      = AVSTREAM_PARSE_FULL;
  56
  57     av_set_pts_info(st, 64, 1, 100);
  58
  59     return 0;
  60 }
  61
  62 static int nc_read_packet(AVFormatContext *s, AVPacket *pkt)
  63 {
  64     int size;
  65     int ret;
  66
  67     uint32_t state=-1;
  68     while (state != NC_VIDEO_FLAG) {
  69         if (url_feof(s->pb))
  70             return AVERROR(EIO);
  71         state = (state<<8) + get_byte(s->pb);
  72     }
  73
  74     get_byte(s->pb);
  75     size = get_le16(s->pb);
  76     url_fskip(s->pb, 9);
  77
  78     if (size == 0) {
  79         av_log(s, AV_LOG_DEBUG, "Next packet size is zero\n");
  80         return AVERROR(EAGAIN);
  81     }
  82
  83     ret = av_get_packet(s->pb, pkt, size);
  84     if (ret != size) {
  85         if (ret > 0) av_free_packet(pkt);
  86         return AVERROR(EIO);
  87     }
  88
  89     pkt->stream_index = 0;
  90     return size;
  91 }
  92
  93 AVInputFormat nc_demuxer = {
  94     "nc",
  95     NULL_IF_CONFIG_SMALL("NC camera feed format"),
  96     0,
  97     nc_probe,
  98     nc_read_header,
  99     nc_read_packet,
 100     .extensions = "v",
 101 };