TABLE OF CONTENTS When video signals are transported over an IP network, they are most often compressed. In this context, compression means to reduce the number of bits that are required to represent the video image. Video technology users are free to choose whether or not to use compression for their video signals. However, it is important to understand that the choice of a compression method can sometimes mean the difference between success and failure of a video networking project.
Many communication systems that have become commonplace in the past few years depend on compression technology. For example, digital mobile telephones use compression to increase the number of users who can be served in a given area (by using less radio bandwidth per user) and to increase the amount of time that a mobile handset can be used between battery charges. Digital cameras use data compression to fit more pictures into a fixed amount of storage. MP3 players use compression to take files from audio CDs and make them small enough to fit into the memory of a portable player. Compression allows a 2-hour movie to fit onto a 4-inch DVD in place of a 12-inch video Laserdisc or an 812-foot (248-m) long VHS tape. Satellite television uses compression to place multiple video channels into the space formerly occupied by a single analog video channel, allowing hundreds of video channels to be distributed economically to viewers. An understanding of video and audio compression is essential to understanding and using modern video transport...
