VITC

Acronym for Vertical Interval Time Code. Generally pronounced VIT-see. VITC is a type of time code — generally SMPTE time code — that is encoded into the vertical blanking interval of a video signal, as opposed to LTC, which is normally recorded on an audio track of an audio or video machine. VITC is actually part of the picture information, as opposed to audio, but is not able to be seen under normal circumstances because it occurs during the vertical blanking interval of a picture. The vertical blanking interval is where the CRT electron gun scanner (which is what “paints” the picture on the screen) goes from the bottom right corner of the screen to the beginning of the next field (or frame) at the top left corner. In order to avoid drawing a diagonal line across the screen the signal is “blanked” out during this movement, thus we have the term vertical blanking interval, and this is where VITC is found. We can’t see it, but it can be read by synchronization equipment designed for it. VITC has some benefits over LTC. For example, it provides the ability to keep machines locked (synchronized) even while playback is paused. In just the same way that the rotating head (helical scan) paradigm of video allows one frame to be continuously painted (in still form) on your screen while the deck is paused, it also can continue to output the VITC value for that frame. Other benefits include time code that is almost by definition resolved to the video frame rate, and the fact that there is no need to use an audio track for time code. One of the down sides for VITC is that in most video machines it’s impossible to get usable time code off the tape while the machine is fast forwarding or rewinding. Nevertheless it is very commonly used in video production.