Porn. Its availability on VHS was one of the deciding factors in the VHS vs. Betamax video format war of the late20th Century. From about 1976 onwards, in fact.

Sony refused to allow pornography to be released on what wasconsidered by many to be its superior Betamax cassette format. Lower cost, thewide range of recorders and long recording times also helped VHS win through ina classic example of what happens when rival formats slug it out for consumeracceptance.

Today: Blu-ray vs. HD DVD

Unbowed, Sony is at it again.Backed by long-time ally Philips, along with Sun, Dell, Pioneer, TDK and Apple,the company aims to make Blu-ray the number-one high-definition format.

Microsoft, Sanyo, Toshiba, Intel and RCA think otherwise, however, and havethrown their considerable weight behind HD DVD . Many pundits are predicting yetanother titanic struggle between industry giants, but they're likely to bedisappointed for a number of reasons.

Just as Betamax tapes didn't work in a VHS recorder, so Blu-ray discs don't work in an HD DVD player. And vice-versa. However, while VHS tapes were noticeably bigger than their Betamax rival, you'd be hard-pushed to tell the differencebetween a Blu-ray and a HD DVD disc.

Because of their physical form, bothBlu-ray and HD DVD discs can be played by a hybrid player - cue LG's recentlylaunched BH100 . True, it can't access certain interactive features of HD DVDs, but forfolk who just want to watch movies, it's a step in the right direction.

And for those whocan't live without all the extras, there's the newly announced SamsungBD-UP5000 which is a true hybrid player and can access all the features of bothformats. These combo players might well be the way forward. They might even make the format war irrelevant .

Do you need HD?

Of course, who's to say that consumers willreadily fork out for high-definition entertainment? The war between Super Audio CD (SACD) and DVD-Audio was a damp squib because neither high-def CD format really took off. People werecontent to carry on buying CDs, which are easily big enough to render an hour's worth of high-quality audio.

In some ways,it's like broadband 3G services for mobile phones. The vast majority of phone users just wantto make and receive phone calls or send and receive text messages. Internetconnectivity, video snippets of Premiership goals, celeb-gossip alerts and all manner ofother 3G downloads have failed to excite the masses.

So it could be that the new high-def disc formats are simply offering too much data and toomany gimmicky extras (at too high a cost) to an audience that's still content to watch movieson DVD.

And with the rise of on-demand television and widespread TV choice on cable and satellite, you can often skip buying a DVD altogether in favour of waiting for the pay-TV premiere. With HD TV broadcasts now taking off on Sky and Virgin Media , there's a real possibility that both Blu-ray and HD DVD could fail as consumer formats.

Thumbs up for massive storage

It's not all doom and gloom for high-def discs, however. Computer users seekinghigh-capacity storage for data backup represent a potential market for Blu-ray and HDDVD burners.

But the steadily falling cost ofhard-drive storage (a half Terabyte drive retails at less than £100 these days)and a gradual uptake of network storage are mollifying factors. In fact, therise of the network could kill both formats.

After all, if we can back up our computer systems via broadband, accessapplications and compute over the network, then who will actually need physical delivery on disc?

HD DVD trumpets its online connectivity, which will allow movie studios to make extra content available for discs you've already bought. If you can download trailers, extra languages and mini-documentaries in this way, then why not a whole movie? It's arguably what Apple's iTunes is gearing up for.

With iTunes, the recordindustry is already enjoying the cost advantages of online distribution, whilethe battle between MP3, WMA and AAC isn't too important because most replaydevices can handle at least two of these popular compressed audio formats, ifnot all.

Beyond the blue lasers

Meanwhile, as Colossus impartedto Dr Forbin , there is another system. Both Optware and Maxell threatened tolaunch holographic discs in 2006, although neither company got around to it.But if that's the way optical storage technology is headed, we'll be looking ata disc-based format that can handle a theoretical 3.9TB of data. It makesBlu-ray's dual-layer capacity of 50GB per side look a bit insignificant.

It's speculative stuff for sure,but unlike the VHS/Betamax clash we face the possibility that neither Blu-ray nor HD DVD will predominate. And it could be the case that the technology has come too late to take hold, such isthe promise of broadband and HD TV.

Sure, there'll be early adopters keen to buy now before theprice goes down. But they may end up stowing their HD DVD and Blu-ray machinesin the loft alongside the old Betamax recorder. And instead, they'll sign up for insaneamounts of bandwidth before the decade is out.

Words by: Karl Foster