Clock-In

Probably the universal method of converting an analog video signal to digital. Since an incoming video signal arrives one pixel at a time, it is sampled at fixed time intervals (in nanoseconds). Essentially the signal is chopped up into little pieces, much as a chef may chop carrots or celery or bananas into slices. Clocking in has the shortcoming of sometimes taking the last half of one pixel and the first half of the next pixel (pixel straddling) as a new pixel when the incoming analog video was digital at some earlier time; the former pixel footprint remains. This results in loss of horizontal resolution. Interpolation may occur naturally during clock-in and the result varies depending on whether the digital value (sample) is derived from the entire slice (averaged) or only a small portion of the slice. (Additional interpolation may or may not be done later.)