ratDVD: The best way to distribute DVDs online?: "In a Nutshell, it is a CFF - Container Format File - technology whereby all the items contained in a DVD are compressed and enclosed into a single .ratDVD format file.
Unlike, say DiVX for example, this one keeps the whole thing intact so that you do not have to make concessions. It plays ingeniously on compression rates and introduces one or two goodies like Dolby Virtual Surround AC-3. More interestingly, it opens up the opportunity for those enterprising enough to sell ratDVD compatible players."