Sony unit to trial content with a 'consume by' date

A subsidiary of the electronics maker Sony is to sell downloadable movie files that self-destruct after a given time.

According to Japanese newspaper Nikkei Business Daily, the So-net ISP will soon trial the service in Japan.

Many digital content providers currently use encrypted streaming to prevent users saving and copying movie files. But the downside is that the quality of the video suffers, as it is reduced in size for web transmission. In addition, users must stay online to view the feed.

However, allowing downloads of movie files opens the door to illegal copying.

To sidestep these issues, So-net's new service allows users to download the content from its website to their hard drives - but those hoping to add the file to a permanent collection or to copy it will have their attempts frustrated.

The firm has incorporated a DRM (digital rights management) technology from software maker Japan Wave which makes copying impossible, the report said.

Instead of saving the video to a single file and location, Japan Wave's technology splits the data into numerous directories on the hard disk. Users will need to download special software to play back the various pieces as a continuous movie.

There's a second layer of protection: Those who manage to join up the files won't be able to use them for very long. Software embedded in the file will cause it to self-destruct after a given time, said the report.

So-net's approach to DRM is part of a growing effort by providers to find robust copy protection without restricting the user's rights to enjoy the content.

Earlier this month, Disney announced plans for a trial in the US. The film-maker said it will start renting self-destructing DVDs which automatically become unplayable after a two-day period.

Major movie studios in Hollywood are also turning up the heat, joining forces in a slew of lawsuits against US-based DVD copying software makers like DVDBackupbuddy.com and DVDSqueeze.com.