A dual quad-tree based variable block-size coding method

Recent video coding standards with hybrid structure adopt variable block-size processing techniques including variable block-size motion estimation and compensation, variable block-size intra prediction, and variable block-size transform. This paper gives analysis on the variable block-size techniques based on software simulations, and variable block-size transform is specially studied. As a result of the analysis, a generalized dual quad-tree based variable block-size coding (DQTC) structure is proposed. This structure also shows good flexibility and expansibility, in which the prediction block-size set and the transform block-size set can be configured according to requirements and the implementation complexity constraints. Simulation results show a considerable performance improvement for the proposed structure with low implementation complexity while the coding block-size sets and parameters are optimized.

Research highlights
► Segment different regions into blocks with a quad-tree structure for prediction.
► Further segment each inter predicted residue block into sub-blocks to be transformed.
► For intra prediction, the same block-sizes as the prediction are used for transform.
► The available block-size sets for prediction and transformation can be configured.
► Apply different quantization strategies for different coding block-sizes.