A key situation to avoid is redundant video processing. What do I mean? Redundant processing is the practice of passing video from one RF or composite video port to another. This practice requires the individual components of the system to decode the video signal, process it, and re-encode it again to send it out the composite port. This situation occurs predominantly with the use of VCRs. Redundant processing is a lengthy path that degrades video performance significantly.

The old adage, "you get what you pay for", has definite relevance with respect to video processing. The decoding task is daunting and not many equipment and display manufacturers devote the time or development expense to this complex process. Of all the steps required to return from composite video to RGB, the process of separating luminance (Y channel) from chrominance (C channel) is the most difficult. This tells us that we should, at a minimum, distribute S-video signals if not component or RGB. Take a look at Figure 3 for the concept of the ideal video distribution approach.

Figure 3 — An ideal video distribution setup

Determine which piece of equipment in the video system provides the best video processing (decoding) and concentrate all, or as much, of the video routing through that unit. For example, if the display device in use has an excellent NTSC decoder, then designing a composite video distribution system that switches (routes) all composite video to the display will provide good results. In many cases, the display does not have the best NTSC processor. Displays may be optimized for RGB data display, for example. In this case, process the video through an external NTSC decoder, high quality line doubler, or quadrupler.

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