Photo: Switcher Board in University Television Studio by M. Daniels
Type the word “wipes” into a search engine and you will bring up a page full of cleaning products: everything from surface disinfection to disposable washcloths. There are gym wipes for sanitizing gym equipment, hospital wipes, baby wipes, make-up wipes and something called “dude wipes” that I did not investigate for fear of being deluged with ads promoting same.
Wipes in television production are not so different: they are used to clear one television picture away and replace it with another. This magical feat generates from a god-like piece of equipment called “the switcher” (pictured above), which performs three basic functions:
- Selecting video imput from available sources (Camera 1, Camera 2, etc.) and switching one video source for another
- Effecting and controlling transitions between video sources
- Creating or accessing special effects (1)
A wipe is a transition from one video source to another, in which a second image, say from Camera 2, bordered by a geometric shape, gradually replaces all or part of the initial image provided by Camera 1. On the board pictured above you will see two rows of buttons (busses) with numbers. Above those busses, lies the wipe pattern matrix which provides a selection of six geometric shapes used in transitioning from one video source to another. More elaborate boards have more wipe pattern choices, but the principle stands. (2)
To the far right at the bottom of the screen, lies the fader bar, which, when set to “Wipe,” lowers the voltage on the output from one video source while increasing voltage to the second video source. Put in simple terms, if the fader bar is in the full “down” position, maximum voltage is going to video source A, generated, let’s say, from Camera 1. By raising the fader bar, the voltage feeding source A is lowered until, when the bar is at its midpoint, the voltage flow is equal between source A and a new source B, generated from Camera 2. At this point both images appear on the monitor, creating a split screen. The switcher detects the voltage transition and cuts from source A to source B. This “cut point” is the border between the two images or the edge of the wipe transition. As the fader bar is raised, the cut point or border between images moves until image B occupies the entire screen and image A disappears. (1)
Wipe patterns come in all shapes and sizes, as pictured on the right, (2) can have hard or soft edges, and are as varied as imagination allows, but that is a topic for another day. On the switcher pictured above, the two most basic wipe patterns appear in the top row of the pattern matrix: the simple vertical wipe (3rd button from left, top row) where the cut point is a horizontal line between the two images and the images transition from top to bottom; and the simple horizontal wipe (second button from left, top row), where the cut point is a vertical line between the two images and the transition moves horizontally from left to right, like turning pages in a book. (2)
Personally, I prefer the cleanliness of a simple cut between video sources during a scene. But when transitioning between scenes, wipes can be a valuable tool, when executed well, in creating time lapses, different moods, and many other aesthetic qualities.
For further enlightenment check out:
- Lee, Dana M.; Television Technical Theory Unplugged, 2004:
- Zettl, Herbert; Telivision Production Handbook, Twelth Edition; San Francisco State University, 2015: Page 473