A word about MPEG encoding – It is a complex task to compress the original audio and video content material (approximately 2.5GB of information per minute) and reduce the size of this data into a manageable stream of information that can be placed onto a DVD disc. Data representing each picture frame, contrast and colors of each frame, as well as audio information must all be reduced to fit on a standard DVD disc. In short, a 2 hour movie or about 150GB of uncompressed data would need to be reduced to 4.7GB in order to fit onto a DVD disc.

Accomplishing this task with an MPEG encoder results in a compressed image that can be transferred to a DVD disc for viewing at a later date. The issues involved are: What happens during the data compression operation, and what effect does it have on the finished product? MPEG encoding retains the information about a reference frame (also known as an ‘I’ frame) then scans subsequent frames for differences in the content from frame to frame. The delta data is compressed with the reference frame data and delivers a smaller block of data. Viola – bit savings! While this MPEG description may be simple, the process is not and many factors within the compression (encoder) can affect the final output both in image detail and quality.

The above information was provided by Zapex Technologies, Inc., a company of Brother International, and manufacturer of advanced MPEG-2 encoding boards.