RealNetworks Inc. has sued Walt Disney Co. and other movie studios, claiming they have conspired to eliminate competition in the DVD market.

The Seattle company, which operates the Rhapsody music site and develops software for playing music and video games, filed antitrust counterclaims against Burbank-based Disney, seven other movie studios and the DVD Copy Control Association Inc. in federal court in San Francisco on Wednesday, Bloomberg News reported.

Studios, claiming piracy concerns, won a court order last year barring RealNetworks from marketing a movie backup product called RealDVD. The software is intended to allow users to more easily copy DVD content to their computer. However, the studios contended that it could be used to pirate movies. The studios note they sell special DVDs ?which cost more than a regular DVD – that can be copied once to be stored on a computer as a backup.

Disney has not issued a response to the suit.