Microsoft Corp has got its hands on a suite of digital rights management patents, but one of the companies most likely to be concerned by the move talked down its importance.

Microsoft said it is to pay $7m for Liquid Audio Inc's US an international patents, believed to be around 20 or over in number. Liquid, which is currently being acquired by Alliance Entertainment, will get a royalty-free license to continue to use the patents.

The US patents cover technologies such as digital watermarking, content distribution, audio encoding, loss-less compression and transferring audio to digital playback devices. Microsoft already has a number of patents of its own development in similar fields.

"DRM is a strategic area we've invested in for the last few years," said a Microsoft spokesperson. "The patents will help us realize our long term vision for DRM technology." He declined to outline the vision in question.

While the company has been developing its own DRM technology, which is vital to winning the confidence of the big movie and music producers, it has been accused of being late to the party and has been sued for patent infringement.

Microsoft is embroiled in extensive litigation with InterTrust Technologies Corp over alleged infringements of InterTrust patents in a wide variety of products including Windows Media. But InterTrust said the new Microsoft patents do not concern it.

"It's a mixed bag of patents Liquid Audio has been shopping around for a while," said InterTrust VP of business development Talal Shamoon. "It's a bit of a stretch to call them DRM patents... a patent is only as good as its claims."

Shamoon said Microsoft will have a hard time suing InterTrust based on any of these patents, as InterTrust no longer sells products, having focused on licensing its intellectual property at the beginning of the year.

He added that he did not believe Microsoft could use the patents to defend itself against InterTrust's lawsuits. A Microsoft spokesperson said: "This [acquisition] is not related to those lawsuits."

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