In the mythtv-0.20.* ebuilds there is the following If USE="dvd -dts" then media-libs/libdts will be built but it won't be used by mythtv since dts support will be disabled anyway (per the -dts flag). If USE="dvd dts" then per the dts USE flag media-libs/libdca will be installed by default but at the same time the dvd USE flag requires media-libs/libdts to be installed; but media-libs/libdca has a runtime dependency of !media-libs/libdts. Reproducible: Always
Also, with mythtv-0.21_pre14513.ebuild there is the following: dts? ( media-libs/libdca media-libs/libdts ) When it needs to be dts? ( || ( media-libs/libdca media-libs/libdts ) ) As it is right now it'll try to install both libdts and libdca which block each other.
Fixed. Good eye.