crum@utah-cs.UUCP (Gary L. Crum) (09/25/85)
I would like someone to define "gen lock", and perhaps describe some existing
hardware devices that use gen locked video images for special effects.
Commodore has recently introduced a new 68000 based microcomputer with nice
graphics capability, and this is one of their accessories for it:
(the following is from Commodore's 16-Sep-85 suggested retail price list)
Part # Product Description Price Avail
-----------------------------------------------------------------------------
1300 Genlock An interface to allow the computer to 249.95 Dec
synchronize to external video sources
such as VCRs and laser disks for increased
graphics cababilities.
Do you think that this would allow the Amiga to display and manipulate
external video images on the computer's own screen, e.g., TV in a window?
Additionally, while deciding what VHS VCR to purchase (I eventually chose
the old Magnavox VR8445SL for $699), I noticed the AR8214BK Sync Coupler,
that provides Gen Lock capability for the Magnavox VR8282 video camera.
Thanks.
Gary Crum ARPA: crum@utah-cs
Univeristy of Utah UUCP: ...{seismo,decvax,ihnp4,hplabs}!utah-cs!crumlauren@vortex.UUCP (Lauren Weinstein) (09/25/85)
Very briefly, genlock refers to all video sources running off a common horizontal and vertical (or composite) sync source. In a studio, there is normally a master sync generator for all air-related equipment-- VTRs, cameras, switchers, etc. To do smooth switching, effects, or virtually anything else, you gotta be locked onto a common sync. If a graphics board says it will lock onto external sync, then you can in theory do things like superimpose or key insert graphics onto an external video source. However, there are several things to watch out for: 1) Many boards that claim to have this capability do it badly, resulting in poor supers or insert keying. 2) Many consumer VCRs have pretty crummy sync stability. Graphics "jitter" may result if such machines are used. 3) If you want to have color graphics interact with an external COLOR signal, the circuitry involved is considerably more complex. . Many boards can't handle it. You have to lock onto the colorburst phase of the external signal to keep the board's color signals and the external signal in phase. --Lauren--
brown@nicmad.UUCP (09/27/85)
In article <3475@utah-cs.UUCP> crum@utah-cs.UUCP (Gary L. Crum) writes: >I would like someone to define "gen lock", and perhaps describe some existing >hardware devices that use gen locked video images for special effects. It is the means by which ALL of the video equipment in a TV studio, TV network, pay TV channel, TV production house, etc., keeps all of the equipment in sync. Since the video signal is very time-base dependent, a single source of the TV video sync signal is used. This piece of equipment generates the vertical and horizontal sync pulses. It also generates some other sync sugnals, such as the vertical interval window, the horizontal sync window area, etc. This piece of equipment allows all of the cameras to be in phase, the character generator to be in phase with the cameras, video decks to be in phase (when played back), so that they all can be put through a video switcher board. Genlock is NOT required to just play a video deck onto a TV set. It is needed in order to do ANY kind of video mixing or special effects. >Commodore has recently introduced a new 68000 based microcomputer with nice >graphics capability, and this is one of their accessories for it: >(the following is from Commodore's 16-Sep-85 suggested retail price list) > >Part # Product Description Price Avail >----------------------------------------------------------------------------- >1300 Genlock An interface to allow the computer to 249.95 Dec > synchronize to external video sources > such as VCRs and laser disks for increased > graphics cababilities. > >Do you think that this would allow the Amiga to display and manipulate >external video images on the computer's own screen, e.g., TV in a window? Yes, I suppose that it could. But the Amiga will need a Analog to Digital converter first. Without seeing the complete description of the 1300, it is kind of hard to determine what they meant it for. One use would be to be able to create graphics images so that they could be put through a video switcher, allowing mixing of the Amiga's graphics images with other signals. The ideas of this are really up to the imagination of the video user. But, it is the starting point of being able to mix the Amiga's TV signal with other signals. One last point to remember about the Amiga. The graphics are SO MUCH BETTER than what you can get onto a regular TV screen. Mixing the Amiga with regular video may lead to disappointment. Just keep that in mind. >Additionally, while deciding what VHS VCR to purchase (I eventually chose >the old Magnavox VR8445SL for $699), I noticed the AR8214BK Sync Coupler, >that provides Gen Lock capability for the Magnavox VR8282 video camera. Same deal with the camera, as with the Amiga. A means of allowing the camera's signal to be mixed with other signals. Very few home cameras have the ability of being genlocked to the outside world. -- Mr. Video {seismo!uwvax!|!decvax|!ihnp4}!nicmad!brown