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 #include "demux.h"
  26 #include "internal.h"
  27
  28 #define NC_VIDEO_FLAG 0x1A5
  29
  30 static int nc_probe(const AVProbeData *probe_packet)
  31 {
  32     int size;
  33
  34     if (AV_RB32(probe_packet->buf) != NC_VIDEO_FLAG)
  35         return 0;
  36
  37     size = AV_RL16(probe_packet->buf + 5);
  38
  39     if (size + 20 > probe_packet->buf_size)
  40         return AVPROBE_SCORE_MAX/4;
  41
  42     if (AV_RB32(probe_packet->buf+16+size) == NC_VIDEO_FLAG)
  43         return AVPROBE_SCORE_MAX;
  44
  45     return 0;
  46 }
  47
  48 static int nc_read_header(AVFormatContext *s)
  49 {
  50     AVStream *st = avformat_new_stream(s, NULL);
  51
  52     if (!st)
  53         return AVERROR(ENOMEM);
  54
  55     st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
  56     st->codecpar->codec_id   = AV_CODEC_ID_MPEG4;
  57     ffstream(st)->need_parsing = AVSTREAM_PARSE_FULL;
  58
  59     avpriv_set_pts_info(st, 64, 1, 100);
  60
  61     return 0;
  62 }
  63
  64 static int nc_read_packet(AVFormatContext *s, AVPacket *pkt)
  65 {
  66     int size;
  67     int ret;
  68
  69     uint32_t state=-1;
  70     while (state != NC_VIDEO_FLAG) {
  71         if (avio_feof(s->pb))
  72             return AVERROR_INVALIDDATA;
  73         state = (state<<8) + avio_r8(s->pb);
  74     }
  75
  76     avio_r8(s->pb);
  77     size = avio_rl16(s->pb);
  78     avio_skip(s->pb, 9);
  79
  80     if (size == 0) {
  81         av_log(s, AV_LOG_DEBUG, "Next packet size is zero\n");
  82         return AVERROR(EAGAIN);
  83     }
  84
  85     ret = av_get_packet(s->pb, pkt, size);
  86     if (ret != size) {
  87         return AVERROR_INVALIDDATA;
  88     }
  89
  90     pkt->stream_index = 0;
  91     return size;
  92 }
  93
  94 const FFInputFormat ff_nc_demuxer = {
  95     .p.name         = "nc",
  96     .p.long_name    = NULL_IF_CONFIG_SMALL("NC camera feed"),
  97     .p.extensions   = "v",
  98     .read_probe     = nc_probe,
  99     .read_header    = nc_read_header,
 100     .read_packet    = nc_read_packet,
 101 };