(New) What is IPTV? How does IPTV work?
True, there's always a choice of channels, but the selection is still quite limited and unless you record programs in advance, you can only watch them when they're broadcast.
Wouldn't it be better if watching TV were more like browsing the Web, so you could pick the program you wanted to watch whenever and wherever you felt like watching it?
That's one of the promises of IPTV (Internet Protocol Television), which uses Internet technology to deliver TV programs "on demand." How does it work?
What benefits will it bring us? What challenges will the broadcasters and telephone companies face delivering these new services? Let's take a closer look!
What is IPTV?
Not the kind of connection you have today, which can probably handle only 1–10 Mbps (million bits per second—roughly the amount of information in an average novel entering your computer every second!), but a broadband line with about 10 times higher bandwidth (information carrying capacity) of maybe 10–100Mbps.
You watch the program either on your computer or with a set-top box (a kind of adapter that fits between your Internet connection and your existing television receiver, decoding incoming signals so your TV can display Internet programs).
From the viewpoint of a broadcaster or telephone company, IPTV is somewhat more complex.
You need a sophisticated storage system for all the videos you want to make available and a web-style interface that allows people to select the programs they want.
Once a viewer has selected a program, you need to be able to encode the video file in a suitable format for streaming, encrypt it (encoding it so only people who've paid can decode and receive it), embed advertisements (especially if the program is free), and stream it across the Internet to anything from one person to (potentially) thousands or millions of people at a time.
Furthermore, you have to figure out how to do this to provide a consistently high-quality picture (especially if you're delivering advertising with your programming—because that's what your paying advertisers will certainly expect).
Three types of IPTV
With a service such as Netflix (an online movie website), you select a TV program or movie you want to watch from a wide range, pay your money, and watch it there and then.
A different kind of IPTV is being offered by some of the world's more enterprising TV broadcasters. In the UK, the BBC (British Broadcasting Corporation) makes its last week's programs available online using a web-based streaming video player called the BBC iPlayer.
This kind of service is sometimes called time-shifted IPTV because you're watching ordinary, scheduled broadcasts at a time that's convenient for you.
The third kind of IPTV involves broadcasting live TV programs across the Internet as they're being watched—so it's live IPTV or IP simulcasting. All three forms of IPTV can work either using your computer and an ordinary web browser or (for much better quality) a set-top box and an ordinary digital TV.
All three can be delivered either over the public Internet or through a managed, private network that works in essentially the same way (for example, from your telephone and Internet service provider to your home entirely through the provider's network).
What is the "Internet Protocol" on IPTV?
IPTV stands for Internet Protocol TV—but what does "Internet Protocol" mean? It's the essence of how the Internet works.
Send an email to a friend or download a web page and the information you set in motion doesn't travel in one big lump, as you might expect. Instead, it's broken up into lots of small pieces, known as packets, each of which may be "switched" (sent) to its destination by a different route. Packet switching, as this is known, is the basic principle of how any information travels over the Internet.
The computers that link the Net together don't know what any given packet means or what it does. All they know is the IP address (a numeric "house and street name" given to every computer on the Internet) where the packet has to go—and they treat all packets equally.
The Internet isn't designed to do a particular job, such as delivering emails: it's simply a highly efficient, computerized "postal" system for delivering zillions of packets. The simple but amazing consequence of this is that as long as you can turn information into packets, you can send it over the Internet—whatever the information might be.
That's why the Internet can be used for sending emails, downloading web pages, making telephone calls (using a technology known as VoIP (Voice Over Internet Protocol), watching TV—and doing a dozen other things that have not yet been invented. If someone had designed the Internet more rigidly, purely for shuttling emails, for example, using it for other things, such as telephone calls or TV, might not have been possible.
How does IPTV work?
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.
Sometimes the original program will be in digital format already; sometimes it will be in the form of a standard, analog TV picture (known as SD format) that needs an extra bit of processing (analog-to-digital conversion) to turn it into digital format.
With current limitations on bandwidth, 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). Once that's done, advertisements have to be inserted, and the information has to be encrypted.
The client and server have a brief, intermittent conversation in which the client requests from the server all the files it needs to build the page you're looking at.
Servers are generally so fast and powerful that many clients can download in this way simultaneously, with very little delay.
So with streaming, a different kind of downloading is used, known as IP multicasting, in which each packet leaves the server only once but is sent simultaneously to many different destinations; in theory, this means one server can send information to many clients as easily as to a single client.
So if you have 1000 people all watching the World Cup final at the same time over the Internet, they'd be receiving packets of streaming video from a single server sent simultaneously to 1000 clients using IP multicasting.
If the same TV provider is simultaneously offering an episode of Friends and some of the original 1000 people decide to "switch channels" to watch it, effectively they switch over from one IP multicast group to another and start receiving a different video stream.
The worldwide nature of the Internet makes it difficult to send information equally as reliably from your server to a local client as to a client on the opposite side of the planet.
That's why IPTV providers often use synchronized, worldwide networks on servers, known as content delivery networks (CDNs), which keep "mirror" copies of the same data; then people in the United States might stream programs from Mountain View, California, while those in Europe might get them from Frankfurt, Germany.
Instead, you're downloading a bit of a file, playing it, and, while it's playing, simultaneously downloading the next part of the file ready to play in a moment or two.
None of the files is stored for very long.
Streaming works because your computer (the client) and the computer it's receiving data from (the server) have both agreed to do things like this.
The Internet successfully links practically all the world's computers because they all agree to talk to one another, in the same way, using prearranged technical procedures called protocols.
Instead of using the ordinary, standard, web-based protocols for downloading (technically, they go by the names HTTP and FTP), streaming involves using protocols adapted for simultaneous downloading and playing, such as RTP (Real-Time Protocol) and RTSP (Real-Time Streaming Protocol).
Multicast streaming involves using IGMP (IP Group Management Protocol; you'll occasionally see books and web pages replacing the M with "Membership"), which allows one server to broadcast to members of a group of clients (effectively, lots of people all watching the same TV channel).
In practice, this means having a highly organized, hierarchical network with a national office known as a super head-end (SHE, where programs are stored and the entire service is coordinated) feeding into regional hubs called video hub offices (VHOs) that, in turn, service local distribution offices linked to set-top boxes in individual homes.
That's why the future of IPTV is likely to involve viewers buying set-top boxes (sometimes called STBs) that receive input from your Internet connection (either via an Ethernet cable or Wi-Fi), decode the signal, and display a picture on your high-definition, widescreen TV.
STBs are effectively standalone computers programmed to do only one thing: receive packets of streamed video, decrypt them, convert them back to video files (MPEG2, MPEG4, or whatever format they were in originally), and then display them as high-quality TV pictures.
Apple TV works broadly this way, using a set-top box to run simple apps on a slimmed-down operating system (tvOS), which manages the process of streaming video via the Internet.
The dongle plugs into an HDMI (high-speed, high-definition digital video) socket on your TV and connects via Wi-Fi to the Internet to stream TV programs, movies, and music director.
Some dongles are entirely self-sufficient: Roku and Amazon Firework this way without any help from a computer or mobile device.
Google's Chromecast is a little bit different: generally, you get it going with your computer, tablet, or smartphone (which effectively becomes a remote control), after which it directly streams your movie or TV program from the Internet.
What's the difference between a set-top-box and a dongle? It's pretty much this simple: a set-top system is a bigger box that contains a faster processor with more memory, so it can give higher quality video output; that makes it better for things like high-performance gaming.
Some companies, such as Amazon and Roku, offer a choice of either a simple, relatively expensive dongle or a more expensive, higher-spec set-top box.
With luck, IPTV may take off in exactly the same way as broadband Internet did in the early 2000s: back then, as more people used the Internet, they felt hampered by the limitations of dial-up connectivity, demanded (and showed they were willing to pay for) higher-quality broadband, and provided enough revenue for the telecommunications companies to upgrade their networks.
Once viewers start to experience the convenience, control, and interactivity of IPTV, higher bandwidth Internet connections that make it possible seem certain to follow.