Patent ID: 6438165
Filing Date: 2002-08-20
Classification: H04N

Abstract:
A video encoder for encoding input images having a plurality of data blocks to provide compressed image data comprising:DCT (discrete cosine transformer) resources configured to DCT the data blocks; quantizing resources coupled to the DCT resources configured to quantize the data blocks to provide quantized data blocks; inverse quantizing resources coupled to the quantizing resources to inverse quantize the quantized data blocks; frame reconstruction resources coupled to the inverse quantizing resources configured to reconstruct previous compressed frames; motion estimation resources coupled to the frame reconstruction resources configured to provide predicted data blocks; subtraction resources coupled to the DCT resources and the motion estimation resources to subtract the data blocks and the predicted data blocks; image preclassifying resources coupled between the subtraction resources and the DCT resources configured to preclassify the data blocks as active and inactive regions wherein the quantizing resources responsive to preclassification of the data blocks limits quantizer values for the active regions; and a data rate output buffer coupled to the quantizing resources configured to provide a data rate signal to the quantizing resources for modifying quantizer values of the quantizing resources in order to maintain a particular target output data rate of the compressed image data wherein the frame reconstruction resources include an automatic scene change detector having a frame comparator configured to provide an average of a combination of distortion, differences in luminance, and color histogram information for comparing the previous frame with the current frame.