Video synthesizer

A Video Synthesizer is a device that electronically creates a video signal.

A video synthesizer is able to generate a variety of visual material without camera input through the use of internal video pattern generators, as seen in the stillframes of motion sequences shown above. It can also accept and "clean up and enhance" or "distort" live television camera imagery. The synthesizer creates a wide range of imagery through purely electronic manipulations. This imagery is visible within the output video signal when this signal is displayed. The output video signal can be viewed on a wide range of conventional video equipment, such as TV monitors, theater video projectors, computer displays, etc.

Video pattern generators may produce static or moving or evolving imagery. Examples include geometric patterns ( in 2D or 3D ), subtitle text characters in a particular font, or weather maps.

Imagery from TV cameras can be altered in color or geometrically scaled, tilted, wrapped around objects, and otherwise manipulated.

A particular video synthesizer will offer a subset of possible effects.

Video Synthesizers as Real Time performance instruments

The history of video synthesis is tied in to a "real time performance" ethic. The equipment is usually expected to function on input camera signals the machine has never seen before, delivering a processed signal continuously and with a minimum of delay in response to the ever changing live video inputs. Following in the tradition of performance instruments of the audio synthesis world such as the Theremin, video synthesizers were designed with the expectation they would be played in live concert theatrical situations or set up in a studio ready to process a videotape from a playback VCR in real time while recording the results on a second VCR. Venues of these performances included "Electronic Visualization Events" in Chicago, |The Kitchen in NYC, and museum installations. Video artist/performer Don Slepian [1] designed, built and performed a foot-controlled Visual Instrument at the Centre Pompideau in Paris (1983) and the NY Open Center that combined genlocked [2] early micro-computers [3] with the Chromaton 14 Video Synthesizer [4] and channels of colorized video feedback.

Analog and early real time digital synthesizers existed before modern computer 3D modeling. Typical 3D renderers are not real time, as they concentrate on computing each frame from, for example, a recursive ray tracing algorithm, however long it takes. This distinguishes them from video synthesizers, which MUST deliver a new output frame by the time the last one has been shown, and repeat this performance continuously ( typically delivering a new frame regularly every 1/30 or 1/25 of a second ) . The real time constraint results in a difference in design philosophy between these two classes of systems.

Video synthesizers overlap with video special effects equipment used in real time network television broadcast and post-production situations. Many innovations in television broadcast equipment as well as computer graphics displays evolved from synthesizers developed in the video artists' community and these industries often support "electronic art projects" in this area to show appreciation of this history.

Confluence of ideas of Electronics and Arts

Many principles used in the construction of early video synthesizers reflected a healthy and dynamic interplay between electronic requirements and traditional interpretations of artistic forms. For example, Rutt & Etra and Sandin carried forward as an essential principle ideas of Robert Moog that standardized signal ranges so that any module's output could be connected to "voltage control" any other module's input. The consequence of this in a machine like the Rutt-Etra was that position, brightness, and color were completely interchangeable and could be used to modulate each other during the processing that led to the final image. Videotapes by Louise and Bill Etra and Steina and Woody Vasulka dramatized this new class of effects. This led to various interpretations of the multi-modal synthesesia of these aspects of the image in dialogues that extended the McLuhanesque language of film criticism of the time.

Image produced by Spectre videosynthesizer

In the UK Richard Monkhouse working for EMS developed a hybrid video synthesiser - Spectre - later renamed 'Spectron' which used the EMS patchboard system to allow completely flexible connections between module inputs and outputs. The video signals were digital, but they were controlled by analog voltages. There was a digital patchboard for image composition and an analog patchboard for motion control.

Evolution into Frame Buffers

Video synthesizers moved from analog to the precision control of digital. The first digital effects as exemplified by Stephen Beck's Video Weavings used digital oscillators optionally linked to horizontal, vertical, or frame resets to generate timing ramps. These ramps could be gated to create the video image itself and were responsible for its underlying geometric texture. Schier and Vasulka advanced the state of the art from address counters to programmable (microcodable) AMD Am2901 bit slice based address generators. On the data path, they used 74S181 arithmetic and logic units, previously thought of as a component for doing arithmetic instructions in minicomputers, to process real time video signals, creating new signals representing the sum, difference, AND, XOR, and so on, of two input signals. These two elements, the address generator, and the video data pipeline, recur as core features of digital video architecture.

The address generator supplied read and write addresses to a real time video memory, which can be thought of as evolution into the most flexible form of gating the address bits together to produce the video. While the video frame buffer is now present in every computer's graphics card, it has not carried forward a number of features of the early video synths. The address generator counts in a fixed rectangular pattern from the upper left hand corner of the screen, across each line, to the bottom. This discarded a whole technology of modifying the image by variations in the read and write addressing sequence provided by the hardware address generators as the image passed through the memory. Today, address based distortions are more often accomplished by blitter operations moving data in the memory, rather than changes in video hardware addressing patterns.

History of Video Synthesizers, Designers, and Artists

before 1960

• Early synesthesic instruments

1962

• Lee Harrison iii's ANIMAC: (Hybrid graphic animation computer) - predecessor to the Scanimate

1966

• Dan slater's custom vsynth's: Dan Slater has built a number of custom homebrew vsynths over the years, & worked with Douglas Trumbull on various films.

1969

• Bill Hearn's VIDIUM: (Analog XYZ driver/sequencer)

1969/70

• Glen Southworth's CVI Quantizer & CVI Data Camera

1970

• groove & VAmpire
  • (Generated Real-time Output Operations on Voltage-controlled Equipment)
  • (Video And Music Program for Interactive Realtime Exploration/Experimentation).

• Lear Siegler's vsynth: Unique Hi-Rez video processor used in the film "Andromeda Strain" and by Douglas Trumbull & Dan Slater

1970/71

• Eric siegel's EVS & Dual Colorizer: Electronic Video Synthesizer (Analog), & Dual Colorizer (Analog)

1970/74

• steven beck's Direct Video Synth & Beck Video Weaver
  • The ever-versatile hardware genius, Steven Beck created some early 70's synths that had no video inputs. They made video purely from oscillations.
  • He also modified a few Paik/Abe units.

1971

• SANDIN IMAGE PROCESSOR: Very early video synth....DIY modular, -Built by Dan Sandin of Chicago.

1972

• Rutt-etra Video Synthesizer: Co-invented by Steve Rutt & Bill Etra, this is an analog computer for video raster manipulation.

1973

• Paik-Abe Video Synthesizer
  • An early creation, residing at the Experimental Television Centre
  • Click on the heading for a dedicated page, w/extensive Real Video Clips

1974

• VSYNTH's by David Jones: Many creations, the most famous being the Jones Colorizer, a four channel voltage controllable colorizer with gray level keyers.

• EMS Spectre: Innovative Video Synthesiser using analogue and digital techniques.

1975

• Don McArthuR's SAID: Don McArthur developed the SAID (Spatial and Intensity Digitizer), an outgrowth of research on the black and white time base corrector

1976

• DENISE GALLANt's vsynth: Created a very advanced analogue video synthesizer in the late 70's.

• Chromaton 14: A fairly small analog video synthesizer, w/color quantizers & can generate complex color images without any external inputs.

1979

• SCANIMATE: Wicked huge thing for broadcast industry
• Chromachron: One of the first DIGITAL VSynths. - Designed by Ed Tannenbaum.

1984

• FairLight Computer Video Instrument: The Farilight CVI was produced in the early 80's, and is a hybrid Analog Digital video processor.

Analog Video Synthesizers

• Scanimate
• Paik/Abe synthesizer
• PCS (Processing Chrominance Synthesizer) created by Eric Siegel 1968
• EVS Electronic Video Synthesizer (Analog) created by Eric Siegel 1970
• Rutt/Etra
• Hearn Colorizer
• Sandin Image Processor
• Vasulka
• Beck Direct
• Jones Colorizer
• Chromaton 14 synthesizer by BJA Systems [5]* Chromascope synthesizer, PAL and NTSC versions
• Spectron - Analog-Digital hybrid, Richard Monkhouse - EMS.
• Videokalos Video Synthesizer
• The Bob System - by Jesus H. - Greece - 2005 [6]

Digital Video Synthesizers

• Sandin Digital Image Colorizer
• Sandin Digital Image Processor
• Beck Video Weavings
• Image Articulator (Vasulka, Schier, Dosch) real time digital data ops by S181 addressing by AMD2901
• Kangaroo Giant Box
• Fluidigeo
• Fairlight CVI
• Recollections ( Ed Tannenbaum ) (http://www.et-arts.com/reco.htm)
• Spectre/Spectron (Richard Monkhouse, Electronic Music Studios UK)
• Video Toaster for Amiga Computer
• Edirol CG-8
• Atari Video Music
• Milkymist (http://www.milkymist.org)

References

Books

• Computer Lib by Ted Nelson

Web

• Nam June Paik (http://www.guggenheim.org/exhibitions/past_exhibitions/paik/paik_top.html )
• Nam June Paik (http://www.paikstudios.com/)
• Rutt-Etra ( http://www.audiovisualizers.com/toolshak/vidsynth/ruttetra/ruttetra.htm )
• Sandin Image Processor ( http://www.audiovisualizers.com/toolshak/vidsynth/sandin/sandin.htm )
• Sandin Image Processor, references to videotapes from, with stillframes ( http://mitpress2.mit.edu/e-journals/LEA/PIONEERS/sandin.html )
• Stephen Beck (Analog and Digital video synths) ( http://people.wcsu.edu/mccarneyh/fva/B/BeckDirectVideo.html )
• Keeling Video Machine design blog ( http://www.lundberg.info/vidsynth/ )
• Fluidigeo synth, designed late 1970s built in early 1980s, patent has good diagrams and text describing archetypical video synthesizer of that era ( http://www.fluidigeo.com/patents/US4791489.pdf )
• Tannenbaum's "Recollections" at Exploratorium ( http://www.kidsart.com/IS/418.html )
• Video Synthesizer List ( http://www.audiovisualizers.com/toolshak/vsynths.htm )
• Videokalos Colour Synthesiser ( http://www.donebauer.net/manifestations/videokalos/features/features.htm )
• The Bob System (http://iknewthem.tripod.com/gear/bob.htm)

Don Slepian music videos: 1. "Beginnings", 1983 - Chromascope Analog Video Synthesizer [7] 2. "Next Time", 1983 - Chromascope with Luma-Keying and Image Processing [8] 3. "Rising Crimson Tide", 1982 - Chromaton 14 Analog Video Synthesizer with colorized video feedback techniques, animations from the Apple II+ micocomputer with genlock board. [9]