implemented by companies that own entire networks. Because IPTV is a closed, managed network, it can deliver full-screen, high- quality video content, unlike streaming media, which is most often still relegated to small-screen and relatively low-quality video. For streaming media, network capacity is a critical issue that needs to be resolved if it is to have any hope of not only keeping up with but converging with IPTV. High-definition TV (HDTV) is set- ting another benchmark that streaming media might struggle with. For telcos in particular, IPTV is laying the foundation for the future, allowing the provider to serve the customer with a bundle of offerings, as well as establish- ing a position in the nascent market for online video distribution. Aside from TV, there are a multitude of opportunities for future multimedia applications that involve the integration of voice, data, and video. Examples of these types of ser- vices include displaying caller ID on a TV set to being able to program a personal video recorder (PVR) remotely from a handheld device. The IPTV Architecture Using IPTV requires either a PC or a set-top box connected to a TV (see Figure 9.8). The primary underlying protocols used for IPTV are Internet Group Management Protocol (IGMP) version 2 for channel-change signaling for live TV and RTSP for stored video (i.e., VOD). Protocols that use peer-to-peer technology to distribute live TV are just start- ing to emerge. Their primary advantage over traditional distribution models is that they provide a way to share data delivery workloads across connected client sys- tems as well as the distributor's own server infrastructure, which drastically decreases the operational costs for a stream provider. Video compression formats used for IPTV include MPEG-2, MPEG-4, H.264, WMV (Windows Media Video 9 and VC-1), XviD, DivX, and Ogg Theora. (Compression techniques are discussed in Chapter 10.) Content Providers Broadcast Content TV Channels, Manager Pay-per-View Prerecorded Content Content Protection Other 