The unveiling of the latest iPod with an inbuilt video player has given rise to visions of watching TV on the move. But what are the realities of mobile TV and film?
TV on the move is still a long way off for some
Judging from the coverage given to the new iPod one could be forgiven for thinking it is the first portable video player to arrive on the market.
But in fact there are many other competing products, including Sony's PlayStation Portable, which launched in the UK in September and last year in Japan.
It can play movies and video content and has a bigger screen than the iPod.
Mobile phones too are becoming sophisticated video players, especially with the advent of 3G phone services.
But video on the go has yet to explode in the same way as mobile music, which was worth more than £500m in the first half of this year.
So what are the barriers to TV on the go?
The biggest problem is the dearth of licensed quality TV or film content available for download on to a PC, before it can be transferred to an iPod or similar video player.
Many portable media player owners rely instead on pirated content, often TV programmes and films downloaded from the net.
But what sets the iPod apart is that Apple has signed a deal with Disney's ABC network to allow users to buy episodes of shows after broadcast to watch on the player.
Sony is offering video on its PSP
The available shows include hits such as Lost and Desperate Housewives.
But the days of watching the previous night's episode of EastEnders on the train to work in the morning is still a way off.
Apple has yet to commit to launching TV content in Europe.
There are several barriers to realising portable TV or films in the UK, some of which are being tested at initial stages by a BBC trial.
The BBC has launched a project called the Integrated Media Player (IMP) which allows about 5,000 people access to a range of BBC TV shows for up to seven days after broadcast.
Those doing the trial will be able to choose TV and radio shows to download to their computers.
Using Digital Rights Management software, after seven days the material will be wiped off the users' hard drive and become inaccessible.
Ashley Highfield, the BBC's head of new media, said that transferring that content to a portable device like the iPod would be a "logical next step" but there is no timetable as yet.
The BBC had to arrange the rights with the owners of the programmes, which are often independent production houses.
This has been one of the stumbling blocks to wider access - copyright protection and ownership of the original material, and who has permission to distribute it.
The UK's producers' union Pact says the issue of content being put on the internet is a particularly strong issue for its members now.
In 2004 the Communications Bill handed producers back the rights to their programmes, taking it away from the broadcasters, so any arrangement to offer it for download would have to be bought from the producers.
The video player is an added extra
"The internet and portable players are a potential new platform and offers new revenue streams that can be exploited," said a spokeswoman.
"But there is the issue of protection of rights and piracy which needs to be resolved."
The BBC says another problem which needs ironing out is the cost of distributing the material.
When a show is broadcast on TV it incurs just one cost, but if users were to download programmes whenever they liked it could potentially cost each time it is accessed.
The BBC is getting around this problem for its IMP trial by using peer-to-peer technology, sharing the burden of distribution across users networks rather than from one giant server.
This was the way that file-sharing services for music sites such as Napster originated, sparking the explosion in music downloading.
The future for watching video on a portable player is uncertain, with the latest iPod offering the industry a chance to gauge interest.
Apple chief executive Steve Jobs said the new iPod was "the best music player we've ever made", emphasising the fact that the video element of it was just an added extra not the sole reason for buying it.
Sony does have grand plans for the future, with its chief executive officer Howard Stringer pledging users of the current PSPs "will soon be able to deploy the device's built-in wi-fi to watch video from home entertainment terminals anytime, anywhere in the world".
But, unlike listening music, it is not possible to watch TV while doing things like walking, working or reading.
So the question for the big companies will be asking themselves is how much should they invest in a technology if the demand for the product is not yet proven?