Approximate Sum of Absolute Transformed Differences Hardware Accelerator

Abstract

Motion Estimation and mode decision are the most compute-intensive tasks in recent video encoders. Sum of Absolute Transformed Differences (SATD) is a distortion metric used inside ME and mode decision to decide the best block to be used as prediction for each block to be encoded. To reduce the complexity of SATD calculation, this work proposes an approximate SATD hardware accelerator based on 1D $4\times 4$ Hadamard Transform, in contrast with the precise SATD hardware accelerator that contains a 2D $4\times 4$ Hadamard Transform. The proposed approximate SATD accelerator reduces power dissipation in 66.86% compared to the precise SATD accelerator while increasing BD-BR only by less than 0.748%, which is a better result than SAD accelerator that increases BD-BR in up to 0.830% compared to precise SATD.