An effective CU size decision method for quality scalability in SHVC

The Scalable extension of the High Efficiency Video Coding (known as SHVC) combines the high compression efficiency with the possibility of encoding different resolutions of the same encoded video in a single bitstream. However, this is accompanied with a high computational complexity. In this paper, we propose an effective coding unit (CU) size decision method by restricting the CU depth range to reduce the encoding time for quality scalability in SHVC. Since the optimal depth level in the enhancement layer (EL) is highly correlated to that in the base layer (BL), we can determine the CU depth range in the EL according to the depth of the co-located CU in the BL. Based on the high correlation between the current CU and its spatio-temporal neighboring CUs, the proposed method skips some specific depth levels which are rarely used in the previous frame and neighboring CUs to further reduce the computational complexity. Experimental results demonstrate that the proposed method can efficiently reduce computational complexity while maintaining similar rate distortion (RD) performance as the original SHVC encoder.