 (24 bits/pixel) X (720 X 480 Compression system characteristics and perfor- mance - The nature of video applications makes 2 pixels/frame) = 249 MHz. many demands on the video compression system. CHAPTER Video compression Interactive video applications such as videoconfer- the choice of video encoding algorithms and technology encing demand that the video compression systems to implement. have symmetric capabilities. That is, each partici- pant in the interactive video session must have the same video encoding and decoding capabilities, and 7.4.4 Digital video signals and that the system performance requirements must be formats met by both the encoder and decoder. On the other hand, television broadcast video has significantly Video compression techniques make use of signal models greater performance requirements at the transmitter in order to be able to utilize the body of digital signal because it has the responsibility of providing real- analysis/processing theory and techniques that have been time high quality compressed video that meets the developed over the past fifty or SO years. The design of transmission channel capacity. Digital video system a video compression system as represented by the implementation requirements can vary significantly. generalized model introduced in Section 7.4.2, requires Desktop televideo conferencing can be implemented knowledge of the signal characteristics, and the digital using software encoding and decoding or may re- processes that are used to create the digital video signal. quire specialized hardware and transmission capa- It is also highly desirable to understand video display bilities to provide high quality performance. The systems, and the behavior of the HVS. characteristics of the application will dictate the suitability of the video compression algorithm for particular system implementations. The importance 7.4.4.1 Sampling of analog video signals of the encoder and system implementation decision cannot be overstated, system architectures and per- Digital video 