In a newly filed lawsuit, Lucent claims that the Xbox 360 infringes its patent on MPEG-2 decoding. At the center of the dispute is Patent No. 5,227,878, "Adaptive Coding and Decoding of Frames and Fields of Video," issued by the U.S. Patent and Trademark Office (USPTO) to Lucent on July 19, 1993, according to court papers filed by the company in U.S. District Court in San Diego.

Claim 1 of the '878 patent reads:

1. An apparatus for encoding digital video signals, comprising:
a means for receiving a digital video input signal comprising a succession of digital representations related to picture elements making up at least one frame of a video image, the frame comprising a plurality of interlaced fields;
a means for coding groups of digital representations related to frames of picture elements;
a means for coding groups of digital representations related to interlaced fields in the frames; and
a means responsive to the digital video input signal for producing a field frame coding type signal which directs a selected one, but not both, of the frame coding means or the field coding means to code the digital video input signal.

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