Modern interactive multimedia services, such as the video-on-demand, electronic library, and etc. tend to involve large-scale media archives of audio records, video clips, image banks, and text documents. Thus, these services impose many challenges on designing and implementing new generation database systems. In this paper, we first introduce a new multimedia data model, which could accommodate sophisticated media types, as well as complex relationships among different media entities. Thereafter, an object-relationship media types, as well as complex relationships among different media entities. Thereafter, an object-relational database infrastructure is proposed, to support applications of the data model developed in our project. The infrastructure is designated both as a framework for designing and implementing multimedia databases, and as a reference model to compare and evaluate different database systems. Features of the proposed infrastructure, as well as its implementation into a prototype multimedia database system, are also discussed in the paper.