ssion equipment. In the case of compression equipment, the SMPTE 292 reference is for the input to the compression equipment. The output standard would be based on the particular recorder or transmission channel standard. Transmission bandwidth of a single analog video signal varies by application, but is generally many times greater than an accompany- ing audio signal, even considering stereo or multi-channel sound. Standard definition analog video signals carried on NTSC or PAL transmission facilities are intentionally bandwidth limited to approxi- mately 4 to 5 MHz. This constraint was arrived at as a compromise between picture quality and interference levels in tuner sections of TV receivers. Analog bandwidth of high definition video signals varies according to the scanning structure used, but generally is about two to three times the bandwidth of standard definition video. In the true end-end-end digital TV world, analog channel characteris- tics, primarily bandwidth, need only be concerned with camera front ends and display inputs. In the latter regard, it might even be safe to say that one only need be worried about cathode ray tube displays because flat panel, non-CRT displays don't use analog driver circuitry. Figure 1-3 is a block diagram of a representative video source show- ing basic functions and components, including optics, sensors, color correction, detail enhancement, gamma correction, and encoding. Although this model is based on a live camera, film or telecine cameras used to capture images from film have a very similar archi- tecture, except the image is transferred from the film to the sensors by passing a light source through the film to project image onto the light- sensitive surface of the sensors. PRACTICAL IP AND TELECOM FOR BROADCAST ENGINEERING AND OPERATIONS Image Detail Enhancement Analog Digital Color Gamma Correction Correction Color Gamma Digital Correction Correction Output Color Gamma Correction Correction Control Clock Clocking Source Legend Reflected Image Analog - Digital Co