Internet television (IPTV) is an Internet service offered by network operators and distributed via IP networks or via satellite Internet. The network operator provides the user with the bandwidth required for the transmission of Internet television.
In addition to the provision ofTV programs that can be accessed simultaneously by many customers, the controlled, time-based retrieval of a desired video, video-on-demand( VoD), is another Internet TV service. Viewers can watch what they want to watch at any time, in any place, and on any device. In addition, Internet TV offers the advantage of interactivity over conventional television. Another aspect of IPTV is selective advertising based on viewer needs.
Internet television works interactively, it is transmitted over the Internet and provided by an Internet Service Provider( ISP). It can be provided via mobile networks, via wired networks using xDSL methods, via satellite Internet using GEO satell ites, or via communications satellites using LEO satellites.
TV programs are live streaming or streaming and can be viewed in real time, time-shifted or on demand. For time-shifted viewing, IPTV can be stored on the user's own computer or set-top box via download. For this purpose, in addition to the IP protocol, IPTV uses the Internet Group Management Protocol( IGMP) for channel signaling for live TV, and the Rapid Spanning Tree Protocol ( RSTP ) for time-shifted video-on-demand (VoD). An alternative to IPTV is Over the Top( OTT), which does not require an Internet Service Provider. The decisive factors for the quality and size of the presentation are the computer hardware andsoftware used and the transmission rate provided in the access network.
Parallel to this development, there are approaches to transmit existing pay TV via the Internet to a standard TV set. This approach must be seen against the background of intellectual property protection.
Compression methods for Internet television
For the transmission of IPTV, the data is compressed in video codecs, for example with MPEG-2, MPEG-4, H.264/ AVC, XviD, DivX, WMV9 or another efficient video compression. This allows, for example, High Definition Television( HDTV) to be transmitted at a data rate of about 8 Mbps. This means that data rates ofADSL are just sufficient for Internet television with standard dynamic range; higher data rates are achieved with ADSL2+, VDSL and VDSL2. Passive optical networks( PON) or WiMAXradio technology can also be used in the connection area.
Other aspects for Internet TV are the software for broadcasting different TV programs, encryption and management of video content, the Electronic Program Guide( EGP) with the program offer for several weeks in advance, user accounting and the software for reception and program selection in the set-top boxes. All this is done via the Switched Video Service( SVS).
Due to the increasing convergence of television and the Internet, TV providers and network providers have established IPTV offerings. In addition to commercial offerings, there are various projects that focus on specific market niches. In addition to IPTV, there is also a high-definition variant with a resolution of 1,920 x 1,080 pixels, High-Definition IPTV( HD-IPTV). Internet TV and DVBdigital TV are linked in hybrid TV( HbbTV).