Macroblock-Based Adaptive Loop Filter for Video Compression

In this paper, we propose an adaptive loop filter that can work on macroblock-level encoding. First, we calculate the filter coefficients that minimize the mean square error between original and encoded frames, and we then apply 2D-filtering to the encoded macroblock using the coefficients. In addition to alleviating blockness, the proposed filtering process improves coding efficiency by allowing the use of filtered pixels as reference pixels for consecutive macroblock coding. The experimental results show that the proposed macroblock-based adaptive loop filter (MBALF) methods can achieve 6% bitrate reduction on average, as compared with the H.264/AVC high profile.