Video feedback

Loop delay that occurs when a video camera is pointed at its own playback video monitor

Video feedback is the process that starts and continues when a video camera is pointed at its own playback video monitor. The loop delay from camera to display back to camera is at least one video frame time, due to the input and output scanning processes; it can be more if there is more processing in the loop.

First discovered shortly after Charlie Ginsburg invented the first video recorder for Ampex in 1956, video feedback was considered a nuisance and unwanted noise. Technicians and studio camera operators were chastised for allowing a video camera to see its own monitor as the overload of self amplified video signal caused significant problems with the 1950s video pickup, often ruining the pickup. It could also cause screen burn in on television screens and monitors of the time as well, by generating static brightly illuminated display patterns. In the 1960s early examples of video feedback art became introduced into the psychedelic art scene in New York City. Nam June Paik is often cited as the first video artist; he had clips of video feedback on display in New York City at the Greenwich Cafe in the mid 1960s. Early video feedback works were produced by media artist experimenters on the East and West Coasts of North America in the late 1960s and early 1970s. Video feedback artists Steina and Woody Vasulka, with Richard Lowenberg and others, formed The Kitchen, which was located in the kitchen of a broken down hotel in lower Manhattan; while Skip Sweeney and others founded Video Free America in San Francisco, to nurture their video art and feedback experiments. David Sohn mentions video feedback in his 1970 book Film, the Creative Eye. This book was part of the base curriculum for Richard Lederer of St. Paul's School in Concord, New Hampshire, when he made video feedback part of an English curriculum in his 1970s course Creative Eye in Film. Several students in this class participated regularly in the making and recording of video feedback. Sony had released the VuMax series of recording video cameras and manually "hand looped" video tape decks by this time which did two things: it increased the resolution of the video image, which improved picture quality, and it made video tape recording technology available to the general public for the first time and allowed for such video experimentation by anyone. During the 1980s and into the 1990s video technology became enhanced and evolved into high quality, high definition video recording. Michael C. Andersen generated the first known mathematical formula of the video feedback process, and he has also generated a Mendeleev's square to show the gradual progressive formulaic change of the video image as certain parameters are adjusted. In the 1990s the rave scene and a social return to art of a more psychedelic nature brought back displays of video feedback on large disco dance floor video screens around the world. There are filters for Adobe Photoshop and non linear video editors that often have video feedback as the filter description, or as a setting on a filter. These filter types either mimic or directly utilize video feedback for its result effect and can be recognized by its vortex, phantasmagoric manipulation of the original recorded image.

Douglas Hofstadter discusses video feedback in his book I Am a Strange Loop about the human mind and consciousness. He devotes a chapter to describing his experiments with video feedback. At some point during the session, I accidentally stuck my hand momentarily in front of the camera's lens. Of course the screen went all dark, but when I removed my hand, the previous pattern did not just pop right back onto the screen, as expected. Instead I saw a different pattern on the screen, but this pattern, unlike anything I'd seen before, was not stationary.