libavformat/msnwc_tcp.c

   1 /*
   2  * Copyright (C) 2008  Ramiro Polla
   3  *
   4  * This file is part of Libav.
   5  *
   6  * Libav 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  * Libav 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 Libav; 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
  39 static int msnwc_tcp_probe(AVProbeData *p)
  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
  73 static int msnwc_tcp_read_header(AVFormatContext *ctx)
  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;
  84     codec->codec_type = AVMEDIA_TYPE_VIDEO;
  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 && !pb->eof_reached);
  93
  94     if(pb->eof_reached) {
  95         av_log(ctx, AV_LOG_ERROR, "Could not find valid start.");
  96         return -1;
  97     }
  98
  99     return 0;
 100 }
 101
 102 static int msnwc_tcp_read_packet(AVFormatContext *ctx, AVPacket *pkt)
 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
 134 AVInputFormat ff_msnwc_tcp_demuxer = {
 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 };