Sofdec, formerly known as MPEG Sofdec, is a video container format developed by CRI Middleware Co. Ltd. and initially released in 1996.
Sofdec is essentially a wrapper for MPEG-1 or MPEG-2 video, with ADX-encoded audio. Close ties with CRI meant ADX was widely used across late Sega Saturn and Sega Dreamcast titles, and with the Dreamcast's native support for MPEG, it is perhaps unsuprising that Sofdec was also widely used during this period as a means to link the two technologies. The majority of Dreamcast titles which stream full motion video use Sofdec, while only a small handful of Saturn games do.
Sega continued to use the format after adopting its multi-platform strategy in 2001, however today the technology is considered obsolete, with CRI themselves having since launched successors in ADX 2 and Sofdec 2.
Sofdec videos have the file extension .sfd.