Their is a special handshake at the switch level, its telling the switch you are part of the multicast group so that you will also receive the packets. bellow is an example of registering and receiving on a udp socket in java
// join a Multicast group and send the group salutations InetAddress group = InetAddress.getByName("188.8.131.52"); MulticastSocket s = new MulticastSocket(6789); s.joinGroup(group); // get their responses! byte buf = new byte; DatagramPacket recv = new DatagramPacket(buf, buf.length); s.receive(recv); ... // OK, I'm done talking - leave the group... s.leaveGroup(group);
what you need to do is join the multicast group, then just recv the packets and write them to a file, then I would assume the mpeg2, mpeg4 or however the stream is sent will be a file on your machine that should be playable through another program.