libavformat/msnwc_tcp.c

   1 /*
   2  * Copyright (C) 2008  Ramiro Polla <ramiro@lisha.ufsc.br>
   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
  24 #define HEADER_SIZE         24
  25
  26 /*
  27  * Header structure:
  28  *  uint16_t    ss;     // struct size
  29  *  uint16_t    width;  // frame width
  30  *  uint16_t    height; // frame height
  31  *  uint16_t    ff;     // keyframe + some other info(???)
  32  *  uint32_t    size;   // size of data
  33  *  uint32_t    fourcc; // ML20
  34  *  uint32_t    u3;     // ?
  35  *  uint32_t    ts;     // time
  36  */
  37
  38 static int msnwc_tcp_probe(AVProbeData *p)
  39 {
  40     int i;
  41
  42     for(i = 0 ; i + HEADER_SIZE <= p->buf_size ; i++) {
  43         uint16_t width, height;
  44         uint32_t fourcc;
  45         const uint8_t *bytestream = p->buf+i;
  46
  47         if(bytestream_get_le16(&bytestream) != HEADER_SIZE)
  48             continue;
  49         width  = bytestream_get_le16(&bytestream);
  50         height = bytestream_get_le16(&bytestream);
  51         if(!(width==320 && height==240) && !(width==160 && height==120))
  52             continue;
  53         bytestream += 2; // keyframe
  54         bytestream += 4; // size
  55         fourcc = bytestream_get_le32(&bytestream);
  56         if(fourcc != MKTAG('M', 'L', '2', '0'))
  57             continue;
  58
  59         if(i) {
  60             if(i < 14)  /* starts with SwitchBoard connection info */
  61                 return AVPROBE_SCORE_MAX / 2;
  62             else        /* starts in the middle of stream */
  63                 return AVPROBE_SCORE_MAX / 3;
  64         } else {
  65             return AVPROBE_SCORE_MAX;
  66         }
  67     }
  68
  69     return -1;
  70 }
  71
  72 static int msnwc_tcp_read_header(AVFormatContext *ctx, AVFormatParameters *ap)
  73 {
  74     ByteIOContext *pb = ctx->pb;
  75     AVCodecContext *codec;
  76     AVStream *st;
  77
  78     st = av_new_stream(ctx, 0);
  79     if(!st)
  80         return AVERROR_NOMEM;
  81
  82     codec = st->codec;
  83     codec->codec_type = CODEC_TYPE_VIDEO;
  84     codec->codec_id = CODEC_ID_MIMIC;
  85     codec->codec_tag = MKTAG('M', 'L', '2', '0');
  86
  87     av_set_pts_info(st, 32, 1, 1000);
  88
  89     /* Some files start with "connected\r\n\r\n".
  90      * So skip until we find the first byte of struct size */
  91     while(get_byte(pb) != HEADER_SIZE && !url_feof(pb));
  92
  93     if(url_feof(pb)) {
  94         av_log(ctx, AV_LOG_ERROR, "Could not find valid start.");
  95         return -1;
  96     }
  97
  98     return 0;
  99 }
 100
 101 static int msnwc_tcp_read_packet(AVFormatContext *ctx, AVPacket *pkt)
 102 {
 103     ByteIOContext *pb = ctx->pb;
 104     uint16_t keyframe;
 105     uint32_t size, timestamp;
 106
 107     url_fskip(pb, 1); /* one byte has been read ahead */
 108     url_fskip(pb, 2);
 109     url_fskip(pb, 2);
 110     keyframe = get_le16(pb);
 111     size = get_le32(pb);
 112     url_fskip(pb, 4);
 113     url_fskip(pb, 4);
 114     timestamp = get_le32(pb);
 115
 116     if(!size || av_get_packet(pb, pkt, size) != size)
 117         return -1;
 118
 119     url_fskip(pb, 1); /* Read ahead one byte of struct size like read_header */
 120
 121     pkt->pts = timestamp;
 122     pkt->dts = timestamp;
 123     pkt->stream_index = 0;
 124
 125     /* Some aMsn generated videos (or was it Mercury Messenger?) don't set
 126      * this bit and rely on the codec to get keyframe information */
 127     if(keyframe&1)
 128         pkt->flags |= PKT_FLAG_KEY;
 129
 130     return HEADER_SIZE + size;
 131 }
 132
 133 AVInputFormat msnwc_tcp_demuxer = {
 134     "msnwctcp",
 135     "MSN TCP Webcam stream",
 136     0,
 137     msnwc_tcp_probe,
 138     msnwc_tcp_read_header,
 139     msnwc_tcp_read_packet,
 140 };