Multimedia Databases

The size of multimedia data can make storage, processing, transmission and recption of data very costly.

There are two approaches to cop with multimedia data size:-

• Store data externally to database and you may just store metadata in database


• Reducing size of multimedia data so that they can be stored within database

Object-relational databases offers means of stoing and processing multimedia data, based on SQL:1999. It provides two new data types that can hold media data.th first is "large object" oor LOB data type. THis has two variants, BLOB "binary large object " and CLOB Character large object. Oracle9i supports another datatype for media objects that are stored externally as operating system files (BFILE data type. LOBS in Oracle9i can hold up to 4GB size. A LOB can be broken down to chunks for processing. It also facilitates storing URLs containing audio, image, or video data stored on any HTTP server such as Oracle Application Server, Netscape Application Server, Microsoft Internet Information Server.

for more informaion here. Oracle sql synatx can be found here .

Reducing Media Object's Size

• Signifiacnt reduction in media oobject size can be achieved by data compression using varios algorithms. But while doig compression we have to keep in mind that how much quality loss (in case of loosy compressions) is acceptable while decompression. In an application we can store data in one compression format and transform data in another while transmitting or presentation, so we need to store information about this. IBM's DB2 and Oracle allows us to do so by providing DB2IMAGE and ORDIMAGE types respectively. So we can store following attributes :
• Compression format- such as jpeg,GIFLZW
• Compression Quality value such as LOWCOMP ,HIGHCOmp
• Content format value such as image type/pixel/data format
• FileFormat - such as BMP, TIFF
  

high quality compression is obtained by using MPEG standards.