I was asked to create a video overlay generator. My first response was to try the many other hobby designs already out there. But then I was asked to make the text color. This has not been done previously, except in very expensive broadcast-quality equipment. I took this challenge and after some thought, determined that it was possible using a few video interface chips along with an AVR microcontroller. The key to getting color is to synchronize the color subcarrier, or color burst, signal from the source.
I was able to find the necessary components to do this and to allow a microcontroller to generate the necessary text. The requirement asked for three font sizes and a choice of colors. It also asked for a simple RS-232 interface to present control and text data in either a fixed display or a scrolling banner. The end result is a system that can display 20 characters across the botom of the screen in 3 sizes and 8 colors. There are also 3 scroll speeds available and a timer-controlled fixed display.
Using a simple script-enabled serial terminal program, such as TeraTerm or Procomm, you can created some cool video effcts.
Contact me if you are interested in more details about the hardware and software.
Here are two samples:
Thanks for visiting!