Sunday, April 30, 2006

What is IPTV?

So many people have asked me what IPTV is about, that I have finally decide to write it down. Read on...

In IPTV, IP stands for Internet Protocol. In the world of networking, this protocol is the third layer out of seven layers that together create a complete network capable of transporting content from point A to point B on the Internet. This content can be text, pictures, voice, and, this is where our interest lies - video as well.

Although most people think understanding IPTV is complicated, the basics are very simple. At one level, all we are talking about is the transmission of a file from a server on the Internet (the same server that might also host and transport web pages) to a users PC. In fact it is not very different from the process of serving up web pages - with one exception.

In other words, and this is important, the transport mechanisms of the Internet do not care what you are transmitting. So, a video file can be transmitted in exactly the same manner as say, a web page (an HTML file). The difference of course is that a video file is going to be much, much larger than just about any web page, hence taking (you guessed it) much, much longer to move from point A to point B on the Internet (the exception I was talking about).

You know that famous phrase about a picture being worth a thousand words? True or not, a picture can take about a thousand times more storage than a word. Now, multiply that by 30 (the NTSC frame rate, 25 for PAL – if you are not sure, never mind approximations are OK) to get the amount of information in one second of video. Impressed? Now you can understand why everyone thinks transmitting video over the Internet is a “big” deal! It has less to do with complicated technology than size (i.e. the amount of information transmitted). Of course video files are compressible depending on the type of video in the file, but the point is that they are many orders of magnitude larger than almost any other file.

About three paragraphs ago, I said, “…a video file can be transmitted in exactly the same manner as a web page…” Luckily for me, I did not say “is transmitted”, and that gives me the opportunity to talk briefly about “Streaming Video”, which is often (incorrectly) used interchangeably with IPTV.

First, let me point out that there are many ways in which a video file can be transmitted over the Internet. And most methods of file transfer can be used with most files. The simplest and oldest method of transmitting files uses the File Transfer Protocol (commonly called FTP). A recent and very popular method called BitTorrent allows very fast transfer of files under some conditions – for example, it excels in peer-to-peer networks.
Streaming Video is a more specialized method of transmitting video files. In this method, a portion of any video starts to play in your video player (for example Windows Media Player or Real Player) while the rest of the file is being received. To do this the software essentially creates a “buffer” which fills up as the video is received. At any time, if the connection becomes slow or is briefly interrupted, the video continues to play uninterrupted from the buffer. Meanwhile, in the background, the player attempts to download more of the video into the buffer.

That is the theory anyway. In practice, interruptions and slowdowns of Internet connections are rarely brief. That is why Streaming Video cannot succeed unless, and this is important, unless the people doing it also own the network.

And you cannot own the network unless you think small. But more on this in a later article or blog. Stay tuned.

Copyright (c) Anil Gupte 2005, All rights reserved.

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