Although retail sales on the street are looking pretty glum at the moment with retailers closing their doors by the week it's nice to see a report that sales of Blu-ray movies are up, by an incredible 400%.

The British Video Association have reveled (in a chat with pocket-lint.co.uk) that 1.5 million disk were sold in December. This is great news for Sony, the format and entertainment sales, but lets look try to examine why such a huge jump.

Blu-ray is a new(ish) home movie format, one which had a vicious and fairly long battle with Toshiba's now defunct HD DVD to be the successor to DVD in the home, so 2008 was the first Christmas that consumers had only one high-definition format to choose from, a relief for many I'm sure. Couple this with the fact that the price of the players are coming down to that which consumers beyond the film fanatic are willing to pay and the number of Blu-ray players in the home starts to increase.

HD TVs are also dropping in price and you can currently pick up a decent 1080p TV for well under £1000 if that's too much a decent "HD Ready" can be bought for as little as £300, this together with good sales of the PlayStation 3 which can play Blu-ray movies means that the high definition world is hitting more and more homes, probably by the week.

Now what was the best selling disk on Blu-ray in December, well no surprise to hear it was The Dark Knight (selling nearly 300,000) which was not only one of the more anticipated moves of the year but also one which many people would have wanted on the high-def format, summer action/sci-fi films are what will sell the format.

With all this in mind it's no wonder that sales of the Blu-ray disks are increasing at such a fantastic rate. Don't get me wrong I love Blu-ray and have the full high-def set-up and have enjoyed many films (WALL-E and The Dark Knight are particularly good) on the format, and I hope this surge in sales continues and eventually overtakes DVD, roll on Quantum of Solace it'll be great I'm sure, but it's not really a surprise is it?

There is a bit of controversy circulating around the internet that early adopters of blu-ray disks will lack features of future Blu-ray disks, and although this is true some claims are being made that the early players will not play future disks.

Although the former statement is true, feature on some future disks will not be accessible on certain players, the latter is simply not true.

Lets put this into context, Blu-ray players have a profile, 1.0, 1.1 and in the near future 2.0. Features are categorised in these profiles so for example picture in picture on future disks are part of profile 1.1. If you have an early player that is only capable of 1.0 you will be able to play a 1.1 disk and get the full experience but you wont be able to access the picture in picture feature.

What impact does this have on the current blu-ray player owners? It seems for a majority it will have little impact. One of the reasons why early players are not future proof is that they cannot connect to the internet and so cant be upgraded, this is where the most popular Blu-ray player sold to date has the advantage.

By quite a large margin the best selling player with the largest install base is the Playstation 3 and this is a wireless device which connects to the internet no problem and has already been upgraded to profile 1.1 and the upgrade to 2.0 is just around the corner.

Good news in all this is that one of the standards being introduced for profile 2.0 is the ability to connect to the internet which means that any future upgrades wont be a problem.

If you have been a little bit of an early adopter and you bought a player after November last year then you are probably already set and any player bought then or after that date had to be at least profile 1.1. If you bought one before then just remember you can still watch the film without any loss of picture.

Early adopter generally know that by being the first person on the street to have the latest technology they will probably have an out dated device quicker than the guy next door who waited 2 years before taking the plunge.