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 Libav.
7 *
8 * Libav 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 * Libav 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 Libav; 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
29static 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
47static int nc_read_header(AVFormatContext *s, AVFormatParameters *ap)
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   = 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
63static 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 (s->pb->eof_reached)
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
94AVInputFormat ff_nc_demuxer = {
95    .name           = "nc",
96    .long_name      = NULL_IF_CONFIG_SMALL("NC camera feed format"),
97    .read_probe     = nc_probe,
98    .read_header    = nc_read_header,
99    .read_packet    = nc_read_packet,
100    .extensions = "v",
101};
102