Low-Complexity Adaptive Block-Size Transform Based on Extended Transforms

In this paper, a low-complexity 8times8/4times4 adaptive block-size transform (ABT) scheme is tentatively proposed for the Chinese audio and video coding standard (AVS). In the proposed ABT scheme, an integer 8times8 transform is derived from the integer 4times4 transform used in AVS according to a transform extension principle. The 8times8 transform not only has high energy compacted property but also can be merely implemented within several additions and shifts, and all intermediate results are limited with 16-bit. The 8times8 transform and 4times4 transform can be merged together and share the same scale matrix so that the hardware units and storage resources are efficiently saved for both encoder and decoder. The experimental results on numerous sequences show that the proposed ABT scheme can achieve significant performance improvement for AVS