VIDEO SYNTHESIZER DEVELOPMENTS

This is an intro article to analogue video synthesizers, written by: Jeffrey Siedler

Before the widespread use of digital computers in the manipulation of video imagery, many artists and video experimenters used various analogue electronic methods to generate real-time images on a television screen. Many of these methods were borne from the appropriation of technology from analogue audio music synthesizers and analogue computer techniques and reworking this technology for the creation of video images and video signals. Analogue video synthesis therefore is the creation of video imagery using analogue electronic technology, and many pioneering video artists today have had their early experience using analogue equipment to realise their visual creativity.

The first video synthesizers appeared on the scene almost a decade after the development of completely integrated audio synthesis systems. Video synthesizers are technically more complex than audio synthesizers with video signals covering a frequency spectrum 100 times greater than for audio signals, and must be constructed according to precise timing synchronisation - the signal must be time-based for a viewable picture to emerge. Because of this reason, the development of video synthesizers had taken longer to emerge compared to its audio counterpart (Dewitt in Vasulka, 1992).

A wide variety of electronic instruments have been constructed by engineers and artists since the mid 1960s. Each imaging system that had been developed reflected the technical and artistic capabilities of its maker - in some systems the resultant image is the product of the inherent circuit design, in other systems the electronics produce a more specific visual or psychological effect (Beck in Schneider & Korot, 1976).

CAMERA IMAGE PROCESSOR TYPES
These devices typically include such units as colourizers which add chrominance to a monochrome signal. Examples include the Fairlight Electric Paintbox, the Paik/Abe video synthesizer and the Cox Box.

DIRECT VIDEO SYNTHESIZER TYPES
These instruments construct an entire video signal and image without the use of any external camera image. Examples include the Beck Direct Video Synthesizer, the EMS Spectron, the Siegel EVS and the Supernova 12.

SCAN MODULATION / RESCAN TYPES
These devices use the principle of scan modulation to alter the geometry of an image on a monitor. This image is then rescanned by a video camera to transform this image into a proper TV scan picture. Examples include the Scanimate by Computer Image Corp. and the Rutt/Etra Scan Processor.

NON-VTR RECORDABLE TYPES
These instruments include those which generate a video display on a monitor which does not actually produce a standard TV signal waveform. Most are based on the principle of magnetic distortion - using the colour picture tube as if it were an oscilloscope screen. Examples include Bill Hearn’s Vidium and the Tadlock Archetron.
(Beck in Schneider & Korot, 1976)

Further to this there are two main classes of video synthesizer. Most of the synthesizers of the 1970s were analogue. A few later varieties were digital, an example being the Quantel Paintbox. A digital video synthesizer typically samples or generates an image as an array of pixels. These pixels are stored as layers of red, green and blue brightness components of a video signal. The pixels are stored in computer memory. The more pixels in memory results in a sharper image. By storing more layers this results in a greater depth of the colour range of the picture. Digital synthesizers are effective with tasks that require the shifting of information quickly, and are used for many of the special effects seen on television. An example of a digital video synthesizer is the Fairlight CVI (Computer Video Instrument) made in Australia in 1984.

Analogue video synthesizer use memory differently to digital synthesizers. They will usually modify a video signal passing through them in a similar way that an audio signal is processed in an analogue synthesizer. A simple video synthesizer would incorporate oscillators referenced to the field rate of the video screen. These oscillators create divisions on the screen that can be made to move and change size by tuning them against this rate. Each oscillator can be modulated by another creating sinusoidal modulations and signal variations. Some machines incorporate a colourizer. A colourizer assigns different colours to different greyscale brightness levels of a video picture. Controls are provided to adjust the red, green and blue levels for each colour assigned, and the key threshold level where each colour will start to appear. Analogue video synthesizers are effective at real-time treatment of a video signal, and creating dynamic sinusoidal patterns on the screen, which would normally require much slow calculation on digital computers (Ellard, 1990).

Video synthesizers give the video artist enormous creative potential to realise complex colour images and to modulate or affect these images in real-time. Only in recent years has digital-computing power enabled the artist such real-time control over their creations - control that was inherent in analogue imaging systems. Combinations of different synthesizer types give analogue control over almost all dimensional components of a video image.

Today the video synthesizer has been largely replaced by imaging and animation software available to suit the personal computer user. However, video synthesizers fulfilled an important artistic need to provide a direct means whereby an artist could immediately create and dynamically compose colour imagery in real-time. Video synthesizers allowed for a freedom of expression that would compliment visual performances and could be considered performance instruments in their own right.

REFERENCES

Schneider, I. & Korot, B. (editors)(1976) Video Art: An anthology, Harcourt Brace & Jovanovich

Vasulka, W. (1992) Eigenwelt der Apparate-Welt ARS Electronica: Pioneers of Electronic Art, Linz, ARS Electronica

Ellard, T. (1990) Sevcom Booklet No. 5 The Journal of Severed Communications.

FURTHER READING

Artwick, B. (1985) Microcomputer displays, graphics and animation, Prentice Hall.

David, D. (1973) Art and the Future: A history/prophecy of the collaboration between science, technology & art. Thames & Hudson.

Popper,F. (1993) Art of the Electronic Age, Thames & Hudson.


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