An efficient all zero block detection algorithm based on frequency characteristics of DCT in HEVC

Henglu Wei, Wei Zhou, Xin Zhou, Zhemin Duan

Abstract: Like the previous video coding standard, DCT and quantization are also adopted in HEVC. Compared with H.264/AVC, HEVC employs larger transform blocks, which makes the all zero block detection algorithm designed for H.264/AVC inefficient for HEVC. An efficient all zero block detection algorithm aimed at HEVC, especially for 16×16 and 32×32 transform blocks, is proposed in this paper based on frequency characteristics of DCT. By analysing the distribution of residual energy in frequency domain, Hadamard transform is used to evaluate only a part of DCT coefficients which usually consume most of energy. To make the proposed algorithm efficient in complex sequences, a sum of absolute transformed difference based method is used to evaluate the maximum value of the rest of the coefficients. Experimental results show that more than 90% all zero blocks for 4×4, 8×8 and 16×16 transform blocks and about 80% for 32×32 transform blocks can be detected by the proposed algorithm. In addition, about 50% computational complexity in DCT/quantization can be reduced with negligible loss of video quality and compression efficiency.