Multimedia database systems have become more and more important as the
tool to extract and generate additional values from multimedia 'Conte
nts'. In this paper, four multimedia database systems are proposed fro
m the view point of promising contents sources; the Network multimedia
databases, the Stream MM database systems, the Library MM database sy
stems, and the Real world MM database systems. Important problems to b
e solved, i.e., 'what to do', are also discussed for each databases. T
hree concrete multimedia systems by authors' research group, are then
introduced and discussed as the embodiments of these multimedia system
s; (1) the open Global Image Retrieval and Linking System, GIRLS, for
mediation WWW data pace as the network MM database systems, (2) the fl
exible multimedia database platform GOLS, and (3) the higher level aut
horing system for the Stream MM environments.