1. A video encoding apparatus, comprising: a video encoder configured to: generate a prediction block by predicting a current block, generate a residual block by subtracting the prediction block from the current block, encode the residual block by transforming and quantizing the residual block, reconstruct the residual block by inversely quantizing and inversely transforming the transformed and quantized residual block, and reconstruct the current block by adding the prediction block to the reconstructed residual block; and a deblocking filter configured to filter a boundary between subblocks within a frame including the reconstructed current block, wherein a first subblock of the subblocks and a second subblock of the subblocks that engage in the filtering are different from each other in numbers of filtered pixels, depending on one or more predetermined criterion.