Very rare tool done by a person called Zench. It's a wrapper that makes 
use of an official Softdec .dll to multiplex SFD files. This allows 
multiplex by command line (what is necessary for batch encoding). It 
also allows you to multiplex several audio streams on the same .sfd, 
necessary to encode for some games like Sonic Adventure 2. 

Command-line support and multi audio stream encoding is not supported by 
the original Katana SDK encoder (DC Movie Maker).