| 摘要 |
PURPOSE: A down conversion system using a pre-decimation filter is provided to convert and format an encoded high resolution video signal, e.g. MPEG-2 encoded video signals, to a decoded lower resolution output video signal, and more specifically to a down conversion system for the decoder. CONSTITUTION: An apparatus for forming a low resolution video signal from an encoded video signal representing a video image, the encoded video signal being a frequency-domain transformed high resolution video signal, the apparatus comprising: means for receiving the encoded video signal as a plurality of blocks of high resolution frequency-domain video coefficient values, wherein the plurality of blocks comprises a macro block; down-conversion filtering means for weighting selected ones of the high resolution frequency-domain video coefficient values within each block to generate corresponding blocks of filtered frequency-domain video coefficients; inverse-transform means for transforming each block of filtered frequency-domain video coefficients into a block of first-filtered pixel values; pre-decimation filtering means for filtering the first-filtered pixel values in each of the plurality of blocks of first-filtered pixel values across block boundaries to provide corresponding blocks of second-filtered pixel values; and decimating means for deleting selected ones of the second-filtered pixel values within each block to provide blocks of low resolution video signal pixel values. |
