This came up in the course of a curiosity-driven review of the patent status of various audio codecs, and also in a recent MPlayer thread. It would probably be wise not to wait for a cease-and-desist letter before quietly discontinuing the distribution of libdts. See http://developers.videolan.org/libdca.html and http://www.via.ecp.fr/via/ml/vlc-devel/2005-04/msg00230.html . Might want to give derivatives a heads-up too.
I don't say I like it, but it's probably the wrong battlefield on which to fight the "software patent" wars. The patent (US #5,956,674, EP 864 146) is "presumptively valid" to within the relevant legal standard, we already collectively have knowledge of it and can't really pretend otherwise given things that are already in the mailing list archives, and AFAICT (IANAL, TINLA) it can't possibly describe anything other than the tweak of a hack on a kludge that is the DTS format. Contrariwise, given the thicket of claims (49 in the US version, which is a monstrous 261K in HTML), it strikes me as quite impossible to determine whether it is 100% unoriginal without litigation. If it is important to enough DD's to do something other than drop it and give its derivatives and CD/DVD distributors a heads-up (IANADD and it's not actually my problem), then SPI and/or one of its EU sister organizations had better obtain opinion of competent counsel. IANAL, TINLA. FWIW it appears that Philips has also stopped supporting DTS in its DVD-R/RW drives: http://www.licensing.philips.com/licensees/patent/dvdrw/documents760.html . Cheers, - Michael