US Patent 7630436 Video predictive decoding method and apparatus

A video predictive decoding method and apparatus for predicting a current block of a picture. The method includes storing at least one previous product in a memory. The previous product corresponds to a block of a plurality of blocks of the picture. The previous product is the product of a quantized AC coefficient and a quantization scale of the block that the previous product corresponds to. The method further includes determining which block to use as a prediction block from the plurality of blocks, reading from the memory at least one previous product corresponding to the prediction block, and calculating at least one quantized AC coefficient of the current block using the at least one previous product read from the memory.