If you believe the Blu-ray Disc Association, the battle for high definition optical formats is all about storage capacity: 50GB for its format; a measly 30GB for HD DVD. Now all that has changed.

On Friday the DVD Forum - the industry body that sets DVD and next-gen disc standards - approved Toshiba's proposal for a triple-layer HD DVD offering 51GB capacity. That's a whole 1GB better than the best that Blu-ray can do. Woot.

So what does this mean?

In reality, not much. Despite the Blu-ray camp's persistent boasting, very few films actually use Blu-ray's 50GB capacity; while the HD DVD Promotion Group argues that it's not capacity that counts, but the kind of audio-video compression used. The HD DVD camp has always maintained that the H.264 and VC-1 codecs it uses are more efficient than the MPEG2 codec used on many Blu-ray discs.

DVD vs Blu-ray vs HD DVD

All that the 51GB approval really tells you is that one camp has scored yet another meaningless point over the other, when neither format is actually doing very well.

For evidence, just look at DVD sales for Grecian actioner 300. It sold 5.1 million copies in its first week - according to High Def Digest - beating the combined sales of all titles on both Blu-ray and HD DVD format since they launched in the US in early 2006.