Blu-ray Disc is catching up with HD DVD, at least in terms of US pre-recorded media retail sales, the most recently published figures from sell-through video sales tracker Nielsen VideoScan show. In the first two weeks of January, BD media outsold HD DVD.

Nielsen VideoScan's numbers come from US trade publication Home Media Magazine by way of website High-Def Digest. There are no raw sales figures, either by revenue or by units, but an indexed comparison of the two formats' over-the-counter unit sales.

By the end of the first week of January, HD DVD retail sales were 47.14 per cent of BD's. The following week, that figure had fallen to 38.36 per cent. That said, more HD DVDs have been bought in the US in total than BD media, but that's no great surprise because the hardware has been available for longer. Toshiba shipped the first HD DVD player in the US in April 2006 - Samsung's BD player, again the first of its kind, didn't ship until the Autumn.

As of 14 January, BD's retail unit sales were 92.4 per cent of HD DVD's, up from 85.05 per cent at the end of the previous week. At that rate, BD sales should surpass HD DVD purchases very soon.

Earlier this year, HD DVD backers said 175,000 players shipped in the US up to 5 January. That contrasts with the million-plus PlayStation 3s Sony claimed to have shipped by roughly the same date. In both cases, shipments do not necessarily equate to sales, but crucially BD-capable devices are clearly outselling HD DVD machines.

Microsoft is now shipping its Xbox 360 HD DVD drive, of course, and Toshiba offering updated, slimmer HD DVD players too, but it's hard to see them matching the PS3.