What is IPTV?
IPTV (Internet Protocol Television) is a system where digital television services are delivered over the internet by using Internet Protocol. The video channels and programs are delivered to the television sets through a broadband connection, instead of being delivered through the conventional cable or broadcast formats. The video streams are encoded into a series of internet protocol packets and then carried out through the public internet means which can be received by anyone by having a set-top box and a subscription for the service. IPTV is generally provided bundled with the VoIP and the internet access which is referred as “Triple Play” service. So this service is a complete package that allows customers to watch TV, browser the internet and making a long distance calls using the VoIP. This service is typically provided by a service provider using a closed network infrastructure.
Multicasting & Unicasting
IPTV supports both live TV (multicasting) and the stored videos also called Video on Demand (unicasting) services. In order to receive the IPTV signals a computer or a television set with a set-top box is required. The video content is typically compressed using either a MPEG2 or a MPEG4 codec and then sent in the MPEG transport stream via IP multicast in case of the live TV or via IP Unicast in case of VoD. IP multicast is the technology that delivers the video content to various users simultaneously whereas the Unicast technology delivers the video content specifically for each user.
Protocols
The basic protocols used in the IPTV forecasting are the HTTP (Hyper Text Transfer Protocol), IGMP (IP Group Membership Protocol) and RTSP (Real Time Streaming Protocol). HTTP is the protocol that browsers use to communicate with the servers and computers for data transfer. Live TV uses IGMP version 2 for connecting television sets with the multicast stream and switching to another multicast stream while RTSP protocol is used for Video on Demand services.
