SAN FRANCISCO — DVD copying software sold by RealNetworks appears to be an illegal pirating tool, a federal judge ruled Tuesday in a legal battle that's been closely watched in Hollywood and elsewhere.

The Seattle-based company's RealDVD software violates federal anti-piracy law and also goes against a contract RealNetworks signed to gain keys to unscramble DVDs, U.S. District Court Judge Marilyn Hall Patel said.

DVDs are embedded with anti-piracy technology that prevents copying, Patel noted.

Patel's order bars the company from selling its software until the case is resolved, saying the movie industry is likely to prevail in its legal battle with RealNetworks.

The company's software — which costs $29.99 — allows consumers to copy DVDs to their computer hard drives.

RealNetworks has argued buyers of DVDs have a fundamental right to make digital copies for safer and more convenient storage. The company's lawyers said the software contains piracy protections that limit a DVD owner to making just one copy.

But the studios said they have the legal right to retain complete control over how content they've created is distributed.

The lawsuit has incurred widespread wrath from bloggers, digital rights advocates and groups on both sides of the political spectrum.