Coarse grain partial distortion elimination for Hadamard ME in HEVC

The Sum of Absolute Transformed Differences (SATD) computation is one of the most time consuming functions of the High Efficiency Video Codec (HEVC) reference model (HM). Thus, dedicated hardware architectures are demanded for such metric. In HM, the SATDs are computed using the Hadamard Transform (HT) 8×8 or 4×4. When the partition sizes are larger than those two HT sizes listed, the SATD is computed by the composition of smaller ones. To save time and energy, we propose the use of Partial Distortion Elimination (PDE) during block compositions. Such approach reduces in average 9.96% and 19.3% the number of 8×8 and 4×4 SATDs, respectively. Moreover, our method is able to filter up to 14.9% of SATDs for video conferencing and up to 32.4% for screen content. Finally, the energy efficiency of dedicated 8×8 and 4×4 SATD architectures may improve, in average, by 10.76% and 16.84%, with area overheads of only 0.13% and 1.72%, respectively.