System for performing real-time video signal resizing in a data processing system having multimedia capability

摘要

A video adapter for use in multimedia computer data processing system is disclosed. The video adapter is able to perform real time video resizing, such as video downscaling and upscaling, during compression and decompression playback within the multimedia computer data processing system. The data processing system typically includes a central processing unit, an input/output bus, and a memory controller for controlling a system memory and a level 2 cache for sending or storing data from the video adapter. The video adapter includes a bus enable logic, coupled to both the video decoder, video encoder, and field memory, that performs the video upscaling and downscaling. The bus enable logic also allows a video pass-through to allow compression and decompression of full resolution images without the need for upscaling or downscaling. The bus enable logic includes a clocked buffer, coupled to a U clock signal, a first enable gate, coupled in parallel to the clock buffer for passing either a U or V component of the digital video signal, and a second enable gate, coupled to a Y component of the digital video signal. The second enable gate is enabled by a Y enable signal and the bus enable log operates such that the Y component is active for two consecutive clock cycles and the U and V components alternate for the next two consecutive clock cycles such that in a given cycle period, two Y components are passed while one U and one V component are passed.