Originally Posted by Stuart C
Depends how they implement it. If they implement it via the phone line (and it's by no means certain they will, although that would be the cheapest way), then it would run independantly of the current cable TV system. It would also mean that they would not need to wait for the Analogue shut down.
If they implement it on the Cable network, then they may well have to replace every set top box eventually, which would bring a lot of benefits for the consumers (the boxes would almost certainly be faster and support MPEG 4), which would cost a *lot*.
got this off wikipedia
IPTV uses a two-way digital broadcast signal sent through a switched telephone or cable network by way of a broadband connection and a set-top box programmed with software (much like a cable or DSS box) that can handle viewer requests to access to many available media sources.
An IP-based platform also allows significant opportunities to make the TV viewing experience more interactive and personalized. The supplier may, for example, include an interactive program guide that allows viewers to search for content by title or actor’s name, or a picture-in-picture functionality that allows them to “channel surf” without leaving the program they’re watching. Viewers may be able to look up a player’s stats while watching a sports game, or control the camera angle. They also may be able to access photos or music from their PC on their television, use a wireless phone to schedule a recording of their favorite show, or even adjust parental controls so their child can watch a documentary for a school report, while they’re away from home.
Note that this is all possible, to some degree, with existing digital terrestrial, satellite and cable networks in tandem with modern set top boxes. In order that there can take place an interaction between the receiver and the transmitter a feedback channel is needed. Due to this terrestrial, satellite and cable networks for television does not allow interactivity. However, interactivity with those networks can be possible in the combination with different networks like internet or a mobile communication network.
VoD stands for Video on Demand. VoD permits a customer to browse an online programme or film catalogue, to watch trailers and to then select a selected recording for playback. The playout of the selected movie starts nearly instantaneously on the customer's TV or PC.
Technically, when the customer selects the movie, a point-to-point[disambiguation needed] unicast connection is set up between the customer's decoder (SetTopBox or PC) and the delivering streaming server. The signalling for the trick play functionality (pause, slow-motion, wind/rewind etc.) is assured by RTSP (Real Time Streaming Protocol).
The most common codecs used for VoD are MPEG-2, MPEG-4 and VC-1.
In an attempt to avoid content piracy, the VoD content is usually encrypted. Whilst encryption of satellite and cable TV broadcasts is an old practice, with IPTV technology it can effectively be thought of as a form of Digital Rights Management. A film that is chosen, for example, may be playable for 24 hours following payment, after which time it becomes unavailable.