Conditional replacement for improved coding efficiency in fine-grain scalable video coding

A new motion compensation (MC) scheme for fine-grain scalable video coding is proposed. This new scheme uses two MC loops, one for the base layer and one for the enhancement layer. A technique called conditional replacement (CR), which adaptively selects between the base layer and enhancement layer prediction for each enhancement layer DCT coefficient, is used to simultaneously improve coding efficiency and reduce prediction drift, as compared to a scheme that always uses the enhancement layer prediction. A new CR architecture that. uses reference frames stored in the spatial domain, unlike the DCT-domain CR architecture previously proposed for frequency scalability, is presented. Whereas a straightforward implementation of a "spatial-domain" CR would require two extra DCTs for each block, the new architecture uses only one extra DCT per block.