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With traditional TV, programs are broadcast by being turned into radio waves and beamed through the air to a rooftop antenna on your home. The antenna converts the waves back into electrical signals and your TV set decodes them to make its sound and picture (satellite TV works the same way, except the signal bounces into space and back, while cable TV sends the signal directly into your home without radio waves). How is IPTV different?


How does IPTV work?


Storing programs Live programs are streamed as they’re produced, but pre-recorded programs and movies need to be stored in such a way that they can be selected and streamed on demand. Some VOD services limit the number of programs they make available, not


because


they’re short of storage space, but


because


that’s one way to limit the overall


bandwidth of their service and its impact on the Internet.


For example, if the BBC made available every program it’s ever produced on its iPlayer, which is free to use, a significant proportion of the entire UK Internet bandwidth would be taken up streaming TV soap operas and sitcoms, potentially slowing down the network for every other kind of Net traffic.


Preparing programs First, the TV program (either pre-recorded or live) has to be converted into a digital format that can be delivered as packets using


the Internet protocol. Sometimes the original program will be in digital form already; sometimes it will be in the form of a standard, analogue TV picture (known as SD format) that needs an extra bit of processing (analogue-


t o - d i g i t a l conve r s ion) to turn it into digital format.


With current limitations on band


width,


videos also need to be compressed (made into smaller files) so they can


stream smoothly without buffering (periodic delays caused as the receiver builds up incoming packets).


In practice, this means programs are encoded in either MPEG2 or MPEG4 format (MPEG4 is a newer form of video compression that gives higher quality for a similar bandwidth and requires only half as much bandwidth for carrying an SD picture as MPEG2).


Remember Totally Digital is always here to answer any questions you have and can be contacted at info@totally-digital.com or via Facebook “Totally Digital Satellite Solutions”.


QF Focus Magazine


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