| Although there are many variations and implementation techniques, video signals are just a way of transferring visual information from one point to another. The information may be from a VCR, DVD player, a channel on the local broadcast, cable television, or satellite system, the Internet, cell phone, MP3 player, or one of many other sources. Invariably, the video information must be transferred from one device to another. It could be from a satellite set-top box or DVD player to a television. Or it could be from one chip to another inside the satellite set-top box or television. Although it seems simple, there are many different requirements, and therefore many different ways of doing it.
This book will cover the engineering essentials of this important technology. First we’ll define some video terms and concepts.
A color space is a mathematical representation for a color. Initially video contained only gray scale, or black-and-white, information. When color broadcasts were being developed, attempts were made to transmit color video using RGB (red, green, blue) color space data, but that technique occupied too much bandwidth so other alternative color spaces were developed. They will be covered in more detail in Chapter 2.
Component video is video using three separate color components, such as YCbCr (digital), YPbPr (analog), or R’G’B ’ (digital or analog). Composite video uses a single signal to contain color, brightness and timing information.
Compression is an important part of video technology. MPEG stands for Moving Picture Experts Group, an international standards group that develops various compression algorithms. MPEG video compression takes advantage of the redundancy on a frame by frame basis of a normal video sequence. There are several different MPEG standards which we’ll cover in later chapters. |
