1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
|
/*
* Copyright (C) 2008 Ramiro Polla
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavcodec/bytestream.h"
#include "avformat.h"
#include "internal.h"
#define HEADER_SIZE 24
/*
* Header structure:
* uint16_t ss; // struct size
* uint16_t width; // frame width
* uint16_t height; // frame height
* uint16_t ff; // keyframe + some other info(???)
* uint32_t size; // size of data
* uint32_t fourcc; // ML20
* uint32_t u3; // ?
* uint32_t ts; // time
*/
static int msnwc_tcp_probe(AVProbeData *p)
{
int i;
for (i = 0; i + HEADER_SIZE <= p->buf_size; i++) {
uint16_t width, height;
uint32_t fourcc;
const uint8_t *bytestream = p->buf + i;
if (bytestream_get_le16(&bytestream) != HEADER_SIZE)
continue;
width = bytestream_get_le16(&bytestream);
height = bytestream_get_le16(&bytestream);
if (!(width == 320 &&
height == 240) && !(width == 160 && height == 120))
continue;
bytestream += 2; // keyframe
bytestream += 4; // size
fourcc = bytestream_get_le32(&bytestream);
if (fourcc != MKTAG('M', 'L', '2', '0'))
continue;
if (i) {
if (i < 14) /* starts with SwitchBoard connection info */
return AVPROBE_SCORE_MAX / 2;
else /* starts in the middle of stream */
return AVPROBE_SCORE_MAX / 3;
} else {
return AVPROBE_SCORE_MAX;
}
}
return 0;
}
static int msnwc_tcp_read_header(AVFormatContext *ctx)
{
AVIOContext *pb = ctx->pb;
AVCodecParameters *par;
AVStream *st;
st = avformat_new_stream(ctx, NULL);
if (!st)
return AVERROR(ENOMEM);
par = st->codecpar;
par->codec_type = AVMEDIA_TYPE_VIDEO;
par->codec_id = AV_CODEC_ID_MIMIC;
par->codec_tag = MKTAG('M', 'L', '2', '0');
avpriv_set_pts_info(st, 32, 1, 1000);
/* Some files start with "connected\r\n\r\n".
* So skip until we find the first byte of struct size */
while (avio_r8(pb) != HEADER_SIZE && !pb->eof_reached) ;
if (pb->eof_reached) {
av_log(ctx, AV_LOG_ERROR, "Could not find valid start.");
return AVERROR_INVALIDDATA;
}
return 0;
}
static int msnwc_tcp_read_packet(AVFormatContext *ctx, AVPacket *pkt)
{
AVIOContext *pb = ctx->pb;
uint16_t keyframe;
uint32_t size, timestamp;
int ret;
avio_skip(pb, 1); /* one byte has been read ahead */
avio_skip(pb, 2);
avio_skip(pb, 2);
keyframe = avio_rl16(pb);
size = avio_rl32(pb);
avio_skip(pb, 4);
avio_skip(pb, 4);
timestamp = avio_rl32(pb);
if (!size)
return AVERROR_INVALIDDATA;
if ((ret = av_get_packet(pb, pkt, size)) < 0)
return ret;
avio_skip(pb, 1); /* Read ahead one byte of struct size like read_header */
pkt->pts = timestamp;
pkt->dts = timestamp;
pkt->stream_index = 0;
/* Some aMsn generated videos (or was it Mercury Messenger?) don't set
* this bit and rely on the codec to get keyframe information */
if (keyframe & 1)
pkt->flags |= AV_PKT_FLAG_KEY;
return HEADER_SIZE + size;
}
AVInputFormat ff_msnwc_tcp_demuxer = {
.name = "msnwctcp",
.long_name = NULL_IF_CONFIG_SMALL("MSN TCP Webcam stream"),
.read_probe = msnwc_tcp_probe,
.read_header = msnwc_tcp_read_header,
.read_packet = msnwc_tcp_read_packet,
};
|
