DVD SYSTEM INTRODUCTION

DVD SYSTEM INTRODUCTION

DVD systems are now outdated and it has been replaced with USB disk drive and External hard disk drive let’s take look at this tech revolution quickly.

DVD stands for Digital Verstile Disc though commonly called Digital Video Disc. A DVD is very similar to CD (Compact Disc) but has a much larger data capacity. A standard DVD holds about nearly seven times more data then a CD does.

DVDs are of the same diameter and thickness as CDs and are made using some of the same materials and manufacturing methods. Like in a CD, the data on a DVD is encoded in the form of small pits and humps in the track of the disc. However the size of pits and humps a much smaller than in CDs so DVD can store much more data. The humps that makes up the track are each 320nm wide.

This huge capacity means that a DVD has to store a full length MPEG encoded movie as well as lot of other information. MPEG stands for Motion Picture Experts Groupn (U.S.A) that has established standards for compression moving picture. MPEG format is now an acepted standard for data compression. DVD can also be used to store eight hours of CD quality music per side.

DVD discs are made as single side – single layer or single side – double layer. Double side – double layers discs are made for some specific applications.

On single layer DVDs the track always circles from inside of the disc to outside. It a DVD has a second layer the start of this layer’s data track can be at outside of the disc instead of from inside. This allows the player to transition quickly from one layer to the next without any delay in data output.

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