Using a technological quirk, movie disk pirates are selling so-called Blu-Ray disks, which can be made cheaply, and what’s more hard to spot for users.

The rub is in the fact that the average user can’t tell the quality difference between the ultra high-definition and high-priced Blu-Ray format used by Hollywood, and the Advanced Video Codec High Definition (AVCHD) format, which is high-def, but not quite as good as Blu-Ray. The former’s display resolution has 720 horizontal lines versus the latter’s 1,080. Nevertheless, AVCHD’s picture is sharper than ordinary mpeg2-encoded DVDs on high-definition TV sets.

The pirates rip the movies from Blu-Ray disks by conventional means then re-encode them. The lower resolution means they can then be put on ordinary blank DVDs instead of more expensive blank Blu-Ray. The method is therefore quite profitable for pirates, says the MPA, which has made it its mission to battle piracy on behalf of studios owned by Walt Disney Co., Viacom Inc., Sony Corp., News Corp., Time Warner Inc., and General Electric Co.

"We are concerned and are assigning priority to this issue," said Mike Ellis, the Asia-Pacific managing director for the MPA.

The new method came to light last month after a raid on a large stash of such pirated disks in China, which is one of the “leading” countries in software piracy. The bust in the city of Shenzen yielded the warehouse’s collection of 800 disks, all illicit copies of movies ranging from Harry Potter and the Philosopher's Stone to Transformers. The DVDs were packaged in the iconic blue boxes of Blu-Ray Disks, including holograms that make them look like the real thing.

"Pirated DVDs from this region...have been exported all over the world in the last few years. These syndicates are very quick to spot market opportunities," said Ellis.