IPTV is able to deliver both live and stored video, commonly known as video on demand (VOD). The video content of ITP is currently in MPEG2TS format deliver with Internet Protocol Multicast, a means of sending information to different computers at the same time (Frater A2). A new format known as H.264 is being developed to replace MPEG2TS, however (Frater A2). In IPTV standards-based systems, the typical protocol used for IPTV is IGMP version to for channel change signaling with live television and RTSP for VOD. While conventional television technologies like terrestrial and satellite cannot deliver IPTV, cable television can be upgraded to two-way capability so that it can offer IPTV.
IPTV is an emerging technology that in future will be developed to enable a totally interactive experience. There are a number of advantages to IPTV compared to traditional delivery of digital television services.
IPTV Delivery Networks
A wide variety of networks are used in delivering IPTV. There are the basic delivery mechanisms, such as DSL, passive optical networks (PONs) and traditional cable TV lines. In addition, traditional High-speed data networks connecting offices and homes can be used for applications with widely dispersed viewers. IPTV signals are generally delivered from the VSO by means of high-bandwidth IP network, usually by means of optical fiber. Inside a CO/RT these networks are connected to DSLAMs. The basic function of a DSLAM is to act as an Ethernet switch and connect video traffic arriving from the VSO to the DSL lines going out to each views premises. To accomplish this,the DSLAM examines the IP address of every incoming packet and forwards them over whichever DSL circuit connects to the customers device with that IP address.
Iptv and internet- ch-4,page 54 by wes simpson and howard greenfield
Technologies for IPTV
Various technologies are required to implement a practical IPTV system.
Compression- For analog video sources, digital compression is performed on each video signal before it can be transmitted on an IPTV system. Normally this process involves feeding the video signal through some form of MPEG compression system. The compression parameters are strictly controlled to make sure that the resulting digital video stream will be compatible with the rest of the network. Items such as peak video data rate and packet length are made consistent between all of the different video sources to simplify the job of the transport and multiplexing functions. In this stem, a unique program identifier is also added to each video stream so that the packets can be correctly identified later and delivered to the appropriate views.
Transcoding: For video sources that are already in a digital format, it is sometimes necessary to convert them into the format that will be used by the IPTV system. This is done by number of