Patent ID: 6389072
Filing Date: 2002-05-14
Classification: H04N

Abstract:
A video data processing system comprising:an encoding system that is configured to produce an encoding of a plurality of blocks of video data corresponding to a sequence of images for communication to a receiving buffer via a communications channel, the encoding system being operative to: transform the video data by subjecting the blocks of video data to a frequency domain coding to form a plurality of transformed blocks, and quantize each transformed block of the plurality of transformed blocks using a quantization step that is under control of a motion activity map, the motion activity map corresponding to a sequence of motion vectors associated with each block of the plurality of blocks of video data; wherein the motion activity map is initialized to a nominal value for each block, and subsequently modified in dependence upon the sequence of motion vectors associated with each block, so that: the quantization step has a first value that is lower than a prior value for a first block of the transformed blocks if the first block has an associated value in the map that corresponds to relatively small motion vectors, the quantization step has a second value that is higher than a prior value for a second block of the transformed blocks if the second block has an associated value in the map that corresponds to relatively large motion vectors, and the quantization step is clipped to ensure that the quantization step stays between a predetermined minimum bound and a predetermined maximum bound.