Video, an Audiovisual Medium

1 Analog Video Technology

In terms of the history of technology, video emerged with the gradual introduction of the battery-operated Portapak camera by Sony in 1965, the development of fast-forward and rewinding magnetic tapes, and videocassette recorders (VCRs) around 1969. It was not until 1971 that portable video technology with videotapes that could record, play back, rewind, and fast-forward was available, and from 1973 there was a half-inch VCR for amateurs.

Video is in principle an electronic medium like television, with which it shares the basic technical properties of signal transmission and a scan-line image format. One basic difference is the way this technology is used. Television is adjusted so that during a broadcast, the scan lines are synchronized in such a way that image interference (i.e., interruptions and delays in the signal transmission) does not occur; instead, a constant and coherent image impression is generated. In contrast, video is an open, modular system consisting of different components. In video there are various possibilities to record, transmit, and broadcast video signals. They can be produced in the devices themselves (e.g., in a synthesizer). Even in the early days of this medium, in collaboration with engineers, video pioneers such as Nam June Paik, Steina and Woody Vasulka, Dan Sandin, and Gary Hill explored the variety of possibilities of intervening in the synchronization of the signal processes and combining different devices. The processual structure of video allows multiple connections of the devices as well as the exchange of audio and video signals, and due to these specific features has proven to be particularly upgradeable for experimental artistic developments in the area of electronic media.

Like television images, video images are kept in constant motion and reflect the flux of electronic signals. In his didactic video How TV Works (USA, 1977), Dan Sandin demonstrates how light information is transformed into signals inside the camera and how these signals circulate between the recording and the playback devices (in a so-called closed circuit). The electronic signal runs vertically and horizontally and both constructs and reconstructs electronic images in the camera and in the screen. Each video image is assembled from two interlaced half fields that consist of temporally displaced even and uneven lines. In this continuous scan-line process, the video signal has to be stopped at the end of each line and synchronized as compound image information; only then does a recognizable raster image appear on the screen. If this step did not occur, video would consist of open lines in horizontal drift.