Control of video device by multiplexing accesses among multiple applications requesting access based on visibility on single display and via system of window visibility rules

摘要

A method and apparatus for allowing several applications to share a single video overlay resource via multiplexing are disclosed. The multiplexing is accomplished from the application end through a multiplexing abstraction layer provided to the developers of end applications as an application program interface. Through the application program interface, each applications may, at any time, request, release, or modify the attributes of the video overlay device such as picture quality, tuning, source, etc. The application program interface provides all basic functionality of the hardware as accessible through other means including normal operating system support and device driver services.