106 4 THE MEDIA PLAYER AND FEEDING THE SCREENS but since it is still expensive to create modulated digital TV signals, these are seldom used for digital signage applications. The only really efficient application for the RF inputs is to distribute the same message to a larger number of screens (discussed in the Analog RF TV Distribution subsection later in this chapter). INPUT INTERFACES One way to feed content into the media player is via a CD or DVD in the media player's DVD player. However, the most versatile inter- face is the network interface. The key element to all this versatility is the use of Internet Protocol (IP) packets to distribute the content to the media players. The IP packets are then encapsulated into Ethernet packets that can be carried in 8-wire twisted-pair cables (though not all of the wires are used today). The twisted-pair cables use RJ-45 connectors (Figure 4.29). IP can be used to carry any kind of digital information, not just audio, video, and teletext or other metadata as in conventional digital tele- vision systems. In Chapter 5, we will take a closer look at how the media player can use the IP Ethernet interface to retrieve any kind of information, such as files from a server, or to receive streaming content. Figure 4.29 The twisted-pair cable and the RJ-45 connectors are the signature of IP carried by the Ethernet.