Client:
gst-launch-0.10 -v udpsrc multicast-group=239.255.12.42 port=4000 caps='application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264' ! rtph264depay ! ffdec_h264 ! xvimagesink sync=false
Server:
gst-launch -v v4l2src ! video/x-raw-yuv,width=320,height=240 ! x264enc ! rtph264pay pt=96 ! udpsink host=239.255.12.42 auto-multicast=true port=4000
http://ntrg.cs.tcd.ie/undergrad/4ba2/multicast/antony/
http://developer.android.com/reference/java/net/MulticastSocket.html