Thursday, January 1, 2009

IP TV set-top box

IPTV describes a system capable of receiving and displaying a video stream encoded as a series of Internet Protocol packets.Now Telco companies want to turn a "triple play" of voice, data, and video.Now let's see how IP TV works?

The set-top box will connect to the home DSL line and is responsible for reassembling the packets into a coherent video stream and then decoding the contents.The set-top box plays a major role in IP TV system.Our computers can do the same job as the set top box, but most people still don't have an always-on PC sitting beside the TV.So the set-top box came to play.then the quiestio is from where the set-top box get the pictures.Let's examine the source descriptively.

Most video enters the system at the telcom's national headend, where network feeds are pulled from satellites and encoded if necessary (often in MPEG-2, though H.264 and Windows Media are also possibilities).Then the video stream is broken up into IP packets and send via telco's core network.Telco's core network is a massive IP network that handles all sorts of other traffic (data, voice, etc.) in addition to the video.Because they use same network for all kinds of services(calls,internet..).When the company own the entire network it can control the quality of the services as he desire.Quality of service (QoS) tools can prioritize the video traffic to prevent delay or fragmentation of the signal.And with end-to-end control, the telcos can guarantee enough bandwidth for their signal at all times, which is key to providing the "just works" reliability consumers have come to expect from their television sets.With multicast streams, it is much more important to ensure that the network is well-engineered from beginning to end to ensure no errors creep into the video stream.As the user's set-top box only subscribes to the stream it can make no requests for additional information.To overcome this problem, multicast streams incorporate a variety of error correction measures such as forward error correction (FEC), in which redundant packets are transmitted as part of the stream.

How do they send hundreds of channels out to an IPTV subscriber with a DSL line?
They only send a few at a time. When a user changes the channel on their set-top box, the box does not "tune" a channel like a cable system.What happens instead is that the box switches channels by using the IP Group Membership Protocol (IGMP) v2 to join a new multicast group. When the local office receives this request, it checks to make sure that the user is authorized to view the new channel, then directs the routers in the local office to add that particular user to the channel's distribution list.In this way, only signals that are currently being watched are actually being sent.

Though multicast technology provides the answer to the problem of pumping the same content out to millions of subscribers at the same time, it does not help with features such as video on demand, which require a unique stream to the user's home. To support VoD and other service we need another unicast stream.This stream is typically controlled by the Real Time Streaming Protocol (RTSP), which enables DVD-style control over a multimedia stream and allows users to play, pause, and stop the program they are watching.The actual number of simultaneous video streams sent from the local office to the consumer varies by network. The reason is bandwidth.Simultaneous delivery of channels is necessary to keep IPTV competitive with cable.The bandwidth issues is one of the trickiest parts of implementing an IPTV network that will be attractive to consumers.For IPTV to become a viable whole-house solution, it will also need to support enough simultaneous channels to allow televisions in different rooms to display different content.

Because the set-top boxes will use Ethernet and IP, they should be simple to integrate into the existing home network, which includes a user's computer. STBs will be able to pull video and pictures from a home PC and display them on the television, and will also be able to easily network with other STBs on other televisions throughout the house.


Anonymous said...

Pls give me router config for peo tv..I messed it up when doing my internet set up according to installation guide...

Thanks in advance

Pubudu Weerathunga said...

Use only port 4 for PEO TV..
domain name:
IPTV account: your telephone number
system password : last 7 digits of the telephone number
default perantal: 111111

if this is not working you can call peo tv customer support

ckumanayake said...

Dear mr Pubudu,

Can we use my desktop monitor (HDMI port or DVI-D port) to watch PEO TV?
(without using ordinary TV)