Apparatus for processing signals representative of a computer graphics image and a real image

摘要

A video data processing apparatus converts one of NTSC type and VGA type video signals to the other or overlays the two types of video signals and outputs them as either an NTSC type overlaid video signal or a VGA type overlaid video signal. The processing apparatus has two video memories for storing video signal data. One of the two video memories stores solely VGA type video data. The other video memory stores either VGA type video data or NTSC type video data depending upon the particular function being carried out by the processing apparatus. Video data may be read out from the other video memory using different scan rates so that an individually dedicated memory is not required for each type of video data in performing the above-mentioned conversions and overlays.