IPTV
(Internet Protocol Television) is a system where a digital
television service is delivered using the Internet Protocol
over a network infrastructure, which may include delivery
by a broadband connection.
For residential users, IPTV is often provided in
conjunction with Video on Demand and may be bundled with
Internet services such as Web access and VoIP. The
commercial bundling of IPTV, VoIP and Internet access is
referred to as a Triple Play. Adding the mobile voice
service leads to the Quadruple Play denomination.
IPTV is typically supplied by a broadband operator using a
closed network infrastructure. This closed network approach
is in competition with the delivery of TV content over the
public Internet. This type of delivery is widely called TV
over Internet or Internet Television.
In businesses, IPTV may be used to deliver television
content over corporate LANs and business networks. Perhaps
a simpler definition of IPTV would be television content
that, instead of being delivered through traditional
formats and cabling, is received by the viewer through the
technologies used for computer networks.
IPTV covers both live TV (multicasting) as well as stored
video (Video on Demand VOD). The playback of IPTV requires
either a personal computer or a "set-top box" connected to
a TV. Video content is typically compressed using either a
MPEG2 or a MPEG4 codec and then sent in an MPEG2 Transport
stream delivered via IP Multicast in case of live TV or via
IP Unicast in case of Video on Demand. IP Multicast is a
method in which information can be sent to multiple
computers at the same time. The newly released (MPEG4)
H.264 codec is increasingly used to replace the older MPEG2
codec.
