Automatic alignment of video window on a multimedia screen

Abstract

In the preferred embodiment, a method automatically aligning video data with a video window on a display screen in a multimedia system includes the steps of storing a selected color key in a graphics memory circuit, storing a chroma key in a motion video memory circuit, and simultaneously controlling the graphics memory circuit to output graphic signals and the motion video memory circuit to output video signals. The graphics signals are then compared to a stored color key to detect when the color key is transmitted within the graphics signals. When there is a match, a color key detection signal is generated. The outputted video signals are compared with a stored chroma key to detect when the chroma key is transmitted. When there is a match a chroma key detection signal is then generated. A vertical and horizontal offset between the color key detection signal and the chroma key detection signal is then detected, and this offset is used to adjust the timing of the motion video memory circuit so that the color key detection signal and the chroma key detection signal occur substantially simultaneously. This offset is then stored for subsequent operation of the motion video memory circuit. The chroma key stored in the storage locations in the motion video memory circuit is then replaced with the video data to be displayed in the video window.