Multimedia data typically means digital images, audio, video, animation and graphics together with text data. The acquisition, generation, storage and processing of multimedia data in computers and transmission over networks have grown tremendously in the recent past.
This astonishing growth is made possible by three factors. Firstly, personal computers usage becomes widespread and their computational power gets increased. Also technological advancements resulted in high-resolution devices, which can capture and display multimedia data (digital cameras, scanners, monitors, and printers). Also there came high-density storage devices. Secondly high-speed data communication networks are available nowadays. The Web has wildly proliferated and software for manipulating multimedia data is now available. Lastly, some specific applications (existing) and future applications need to live with multimedia data. This trend is expected to go up in the days to come.
Multimedia data are blessed with a number of exciting features. They can provide more effective dissemination of information in science, engineering , medicine, modern biology, and social sciences. It also facilitates the development of new paradigms in distance learning, and interactive personal and group entertainment.
The huge amount of data in different multimedia-related applications warranted to have databases as databases provide consistency, concurrency, integrity, security and availability of data. From an user perspective, databases provide functionalities for the easy manipulation, query and retrieval of highly relevant information from huge collections of stored data.
MultiMedia Databases (MMDBs) have to cope up with the increased usage of a large volume of multimedia data being used in various software applications. The applications include digital libraries, manufacturing and retailing, art and entertainment, journalism and so on. Some inherent qualities of multimedia data have both direct and indirect influence on the design and development of a multimedia database. MMDBs are supposed to provide almost all the functionalities, a traditional database provides. Apart from those, a MMDB has to provide some new and enhanced functionalities and features. MMDBs are required to provide unified frameworks for storing, processing, retrieving, transmitting and presenting a variety of media data types in a wide variety of formats. At the same time, they must adhere to numerical constraints that are normally not found in traditional databases.Contents of MMDB
An MMDB needs to manage several different types of information pertaining to the actual multimedia data. They are:
The last three types are called meta data as they describe several different aspects of the media data. The media keyword data and media feature data are used as indices for searching purpose. The media format data is used to present the retrieved information.
Many inherent characteristics of multimedia data have direct and indirect impacts on the design of MMDBs. These include : the huge size of MMDBs, temporal nature, richness of content, complexity of representation and subjective interpretation. The major challenges in designing multimedia databases arise from several requirements they need to satisfy such as the following:
1) a few sample video frames as an example,
2) a clip of the corresponding audio track or
3) a textual description using keywords.
The recent growth in using multimedia data in applications has been phenomenal. Multimedia databases are essential for efficient management and effective use of huge amounts of data. The diversity of applications using multimedia data, the rapidly changing technology, and the inherent complexities in the semantic representation, interpretation and comparison for similarity pose many challenges. MMDBs are still in their infancy. Today's MMDBs are closely bound to narrow application areas. The experiences acquired from developing and using novel multimedia applications will help advance the multimedia database technology.