There may be more than one way to decode Dolby Digital EX-encoded DVDs -- at least that's what some suppliers believe. But Lucasfilm's THX division needs convincing.
Dolby Digital EX was developed by Dolby Labs and Lucasfilm to add a matrixed rear-center channel to 5.1-channel film and DVD soundtracks. For home theater use, Lucasfilm is licensing the technology as part of its THX Ultra certification program, in which the technology is called THX Surround EX.
At CES, Yamaha and at least two other suppliers will show products that decode the matrixed rear-center channel in DD EX-encoded DVDs and in DTS ES-encoded DVDs -- but the suppliers will do it without a THX license.
As soon the new products are available, the THX division plans to "open them up" to ensure that pending patents haven't been violated, said Monica Dashwood, general manager of Lucasfilm's THX division. Dolby and Lucasfilm have applied for a joint patent on DD EX, she said.
"We will only be able to protect what the patent filing covers," she said. "We will protect our rights, [but] there's nothing we can do to anyone who is not using our technology."
"If they're calling it THX Surround EX," Dashwood added, "that's a trademark infringement." Yamaha is calling its decoding technology Dolby Digital/Matrix 6.1. But whatever suppliers call their matrix-decoding technology, Dashwood asked, "will their description for it be as strong or marketable as THX Surround EX?"
Products equipped with THX EX Surround are said to more accurately reproduce the soundtracks of EX-encoded movies.
In movie theaters and home theaters equipped with rear-center channel speakers, the technology creates a 360-degree soundfield, reproducing such effects as 360-degree flyovers or planes flying overhead from the front through the back wall -- if the soundtracks were encoded that way.