Eac3to: http://forum.doom9.org/showthread.php?t=125966
If you prefer, the software allows you to extract the DTS core from it (meaning it is no longer lossless, but becomes regular lossy DTS without re-encoding).
If that's confusing, as I understand it DTS-HD is an extension of DTS. It's really DTS + extra stuff to make it lossless. The extras stuff can be stripped and an untouched DTS track is left behind.
If you prefer though, Eac3to will also allow you to re-encode to DD.