Questions and Answers
Copyright (c) 1994 Apple Users' Group, Sydney
Republished from Applecations, a publication of the Apple Users' Group, Sydney, Australia.
Source: Internet comp.sys.apple2
Q: What would I be able to do with a Video Overlay Card on a Apple II?
A: The Video Overlay Card is a video mixing device: you can combine an input video signal with computer-generated video, and output that to another device. To make full use of it, you probably need two video recorders, or at least a video camera and a recorder. You could do a reasonable amount with a video camera or recorder and a monitor on the output, but ideally you should use a video recorder on the output.
The most obvious use of it is to add computer-generated subtitles to a video. You can watch TV while you type away on your computer. You can also make and use programs that combine video and computer graphics.
The VOC also has an interlaced graphics mode with doubled vertical resolution, lets you have two different monitor displays, and has an expansion bus if you want to build things like a graphics card or a video digitiser.
Q: What software makes use of the Video Overlay Card?
A: Overlaying graphics or text on video works with any software whatsoever, however, some programs are better than others. In particular, on the Apple IIgs, 320 mode works better than 640 mode. The VOC operates on a "key colour" scheme whereby the key colour becomes transparent, allowing the video source to show through. It therefore helps if you can generate large areas of the same colour on the screen. Software which comes with the VOC allows control of the degree to which the key colour and non-key colours are transparent.

THIS CONTENT COPYRIGHT © 2007, APPLE MACINTOSH USERS' GROUP, SYDNEY
Permission has been obtained to make this material available on the Internet.

Permission is hereby granted for non-profit user groups to republish this content.
PLEASE CREDIT THE AUTHOR AND THE SOURCE: Applecations, publication of the Apple Users' Group, Sydney, Australia

THIS PAGE COPYRIGHT © 2007, ANDREW ROUGHAN