While the current state of web streamed TV might be considerably less than high definition quality, the ability to watch TV from around the world on-demand could completely change when and how we enjoy our favourite shows.

Watching TV shows via the web can be a tricky business. Sure, you can download the latest episode of blockbuster programmes hours after their first transmission via torrent sites. Unfortunately this is normally illegal.

Apple's iTunes and some broadcasters allow users to pay to download content, but downloading can be slow.

What if you want to watch a TV show immediately, when the urge takes you?

While downloading means an entire file has to be transferred before it can be used, streaming sends a continuous flow of data, meaning it can be viewed before the whole file has been received.

A streamed file will often open in a matter of seconds, whereas downloading can of course take much longer.

However, streamed files typically do not remain saved on your hard drive.

Traffic growth

There are however a couple of drawbacks. Reliability is one: there are few things more frustrating then watching streamed content and then losing the stream.

And if you can achieve a descent streaming rate there is still the issue of image quality. Most streamed TV shows do not exactly give HDTV a run for its money.

"One of the challenges is that the internet really isn't set up to deliver high resolution video, and so it needs assistance, help and support to enable it to do so," said Phill Robinson of CacheLogic.

"There are basically two exabytes of traffic that flow over the internet. We have got to that level of traffic growth over the last 20 years. It's going to rise and quadruple over the years to eight exabytes.

"That's a huge volume of data that's going to be shipped over the internet, and the reason is the delivery of video, which has huge file delivery requirements sitting behind it."

Illegal content

Major broadcasters around the world have adopted streaming as a method of viewing limited amounts of content on their websites.

But with just a few web searches it is fairly easy to find and watch hit TV shows via streaming.

In many cases entire seasons are available to view on-demand. The problem is, they are rarely available from the sources that actually own these shows.

While sites like YouTube have publicly been forced to remove copyright content, a host of smaller, below the radar sites provide links to streamed TV shows.

While the sites themselves do not host any of the programmes, they instantly direct users to sites that do.

Traditional broadcasters and movie studios have been comparibly slow in putting their content on the internet because of the problems associated with making money.

"There is sort of a standoff," explained Mr Robinson, "where you can quite easily get illegal content onto your PC, but it's more difficult to get legitimate content onto your PC. With illegal content there is no quality of service, the actual resolution of the videos is quite poor.

"Eighteen million people watch Desperate Housewives every week in the United States. If we were to encode that at a high quality resolution, to deliver over the internet say 2mbps, then it would require 36 terabytes a second of capacity for those 18 million people to watch it over the web."

He added: "The entire internet around the globe runs at between one and 10tbps, so just to deliver one programme to its existing viewing audience would require us to triple or quadruple the current capabilities of the web."

Potential solutions

But technological help is at hand to change the way the internet works.

Caching, having multiple copies of a file on machines closer to the consumer can help with the problem of file delivery latency, and peer to peer (P2P) allows people to share a file amongst other people who have already used it before from their PCs.

"The solution is to combine the two in a hybrid network," Mr Robinson said. "So we have a new generation of P2P technology with a new generation of cache technology that work together to blend the bandwidth from the caches as well as the peers.

"Then we can guarantee a broadcast quality experience from the very first second of the delivery of that particular piece of video."

New services

Recognising the opportunities offered by streaming and P2P, a host of new media outfits have sprung up, each with a different approach to conquering this new video frontier.

Valerio Zingarelli of Babelgum said: "We want to deliver special and also niche content which are not easily available though other platforms.

"Of course we have to propose something which is easy, which is not expensive. For this reason, we are using very simple traditional web connectivity, narrowband. We think that no more than 600-800 kbps is necessary for delivering our content."

An altogether different take on streamed TV, LiveStation uses software acquired from Microsoft's development labs in Cambridge.

The clue is in the name. LiveStation plan to stream news, sporting and entertainment events to computers as they happen.

"I think that people will consume content on the IP platform the moment that the quality of the user experience is good enough," said Matteo Berlucchi, CEO of Skinkers.

"The biggest challenge that we are facing is that the internet infrastructure was not originally designed to support video, you have a lot of bottle necks. But it will take some time for that to be resolved."

All of these offerings are currently still in beta testing, and promise to launch in 2008.

While resolution and reliability issues surround streamed TV, for the moment its widespread appeal remains limited.