An Adaptive Quad-Tree Depth Range Prediction Mechanism for HEVC

A next-generation video coding standard High Efficiency Video Coding (HEVC) provides higher video quality and lower compression bit rate but leads to very high encoding complexity, especially in the quad-tree-based coding tree unit partitioning process. To reduce the computational complexity of HEVC, in this paper, we propose an adaptive quad-tree depth range prediction mechanism. First, the proposed mechanism defines the similar region flag to distinguish between the similar region and the non-similar region. Then, two algorithms, the similar region depth range prediction algorithm and the non-similar region depth range prediction algorithm, are proposed. The similar region depth range prediction algorithm estimates the features of the similar region based on the coding unit depth of this region. The optimal depth of this region can be predicted. The non-similar region depth range prediction algorithm can skip low probability tree nodes based on the depth correlation coefficient, which is calculated based on scene content change. Both the similar region depth range prediction algorithm and the non-similar region depth range prediction algorithm show more than 90% predictive accuracy. Experimental results show that under random access configuration and low delay configuration, the proposed mechanism can yield 28.17% and 32.99% computational complexity reduction with negligible rate distortion performance loss, respectively, compared with HM16.9. The results show that the proposed mechanism is expected to be applied in real-time environments.