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msnwc_tcp.c
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1 /*
2  * Copyright (C) 2008 Ramiro Polla
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "libavcodec/bytestream.h"
22 #include "avformat.h"
23 #include "internal.h"
24 
25 #define HEADER_SIZE 24
26 
27 /*
28  * Header structure:
29  * uint16_t ss; // struct size
30  * uint16_t width; // frame width
31  * uint16_t height; // frame height
32  * uint16_t ff; // keyframe + some other info(???)
33  * uint32_t size; // size of data
34  * uint32_t fourcc; // ML20
35  * uint32_t u3; // ?
36  * uint32_t ts; // time
37  */
38 
40 {
41  int i;
42 
43  for(i = 0 ; i + HEADER_SIZE <= p->buf_size ; i++) {
44  uint16_t width, height;
45  uint32_t fourcc;
46  const uint8_t *bytestream = p->buf+i;
47 
48  if(bytestream_get_le16(&bytestream) != HEADER_SIZE)
49  continue;
50  width = bytestream_get_le16(&bytestream);
51  height = bytestream_get_le16(&bytestream);
52  if(!(width==320 && height==240) && !(width==160 && height==120))
53  continue;
54  bytestream += 2; // keyframe
55  bytestream += 4; // size
56  fourcc = bytestream_get_le32(&bytestream);
57  if(fourcc != MKTAG('M', 'L', '2', '0'))
58  continue;
59 
60  if(i) {
61  if(i < 14) /* starts with SwitchBoard connection info */
62  return AVPROBE_SCORE_MAX / 2;
63  else /* starts in the middle of stream */
64  return AVPROBE_SCORE_MAX / 3;
65  } else {
66  return AVPROBE_SCORE_MAX;
67  }
68  }
69 
70  return -1;
71 }
72 
74 {
75  AVIOContext *pb = ctx->pb;
76  AVCodecContext *codec;
77  AVStream *st;
78 
79  st = avformat_new_stream(ctx, NULL);
80  if(!st)
81  return AVERROR(ENOMEM);
82 
83  codec = st->codec;
85  codec->codec_id = AV_CODEC_ID_MIMIC;
86  codec->codec_tag = MKTAG('M', 'L', '2', '0');
87 
88  avpriv_set_pts_info(st, 32, 1, 1000);
89 
90  /* Some files start with "connected\r\n\r\n".
91  * So skip until we find the first byte of struct size */
92  while(avio_r8(pb) != HEADER_SIZE && !url_feof(pb));
93 
94  if(url_feof(pb)) {
95  av_log(ctx, AV_LOG_ERROR, "Could not find valid start.\n");
96  return -1;
97  }
98 
99  return 0;
100 }
101 
103 {
104  AVIOContext *pb = ctx->pb;
105  uint16_t keyframe;
106  uint32_t size, timestamp;
107 
108  avio_skip(pb, 1); /* one byte has been read ahead */
109  avio_skip(pb, 2);
110  avio_skip(pb, 2);
111  keyframe = avio_rl16(pb);
112  size = avio_rl32(pb);
113  avio_skip(pb, 4);
114  avio_skip(pb, 4);
115  timestamp = avio_rl32(pb);
116 
117  if(!size || av_get_packet(pb, pkt, size) != size)
118  return -1;
119 
120  avio_skip(pb, 1); /* Read ahead one byte of struct size like read_header */
121 
122  pkt->pts = timestamp;
123  pkt->dts = timestamp;
124  pkt->stream_index = 0;
125 
126  /* Some aMsn generated videos (or was it Mercury Messenger?) don't set
127  * this bit and rely on the codec to get keyframe information */
128  if(keyframe&1)
129  pkt->flags |= AV_PKT_FLAG_KEY;
130 
131  return HEADER_SIZE + size;
132 }
133 
135  .name = "msnwctcp",
136  .long_name = NULL_IF_CONFIG_SMALL("MSN TCP Webcam stream"),
137  .read_probe = msnwc_tcp_probe,
138  .read_header = msnwc_tcp_read_header,
139  .read_packet = msnwc_tcp_read_packet,
140 };