Burst.com, the Santa Rosa, Calif., company that sued Microsoft for patent infringement, filed a lawsuit Monday against Apple Computer. The suit is actually a counterclaim in ongoing litigation between the two companies; Apple sued Burst in January proactively seeking a legal declaration that it wasn't infringing patents.

At issue are Burst's patents related to aspects of delivering and playing back audio and video. Burst is claiming that Apple is infringing on those patents in its iPod, iTunes and QuickTime products.

The patents, which were filed beginning in 1988, suggest a shift in the previous broadcast paradigm of delivering audio/video content at a rate commensurate with the playback speed. In contrast to the broadcast paradigm, one aspect of the patented inventions is to transmit the audio and/or video content at a rate faster than playback speed...

Microsoft paid Burst $60 million last year to settle its suit, which covered some of the same patents.