Dynamic estimator selection for double-bit-range estimation in VVC CABAC entropy coding

CABAC is the only entropy coding used in Versatile Video Coding (VVC). This is achieved through multiple estimators approach that provide more accurate predictions by considering different estimated probability results, but CABAC coding requires higher complexity and bit-range accuracy than other approaches. Therefore, there is more potential to refine the performance from the perspective of bit allocation and architecture design. In this paper, a selection method is proposed to determine which estimator is recommended to dynamically perform the current entropy coding. Taking advantage of the double-bit-range architecture, the bits contained in the different estimators are also rearranged based on Most Probable Symbol (MPS$\mathit {MPS}$) determination and Least Probable Symbol (LPS$\mathit {LPS}$) considerations. Experimental reports in the work report that the coding time can be reduced using the proposed method and there is a slight gain in Peak Signal-to-Noise Ratio (PSNR) while saving some Rate-distortion (RD) performance in bitrate. A selection method to determine which estimator is recommended to dynamically perform the current entropy coding. Taking advantage of the double-bit-range architecture, we also rearrange the bits contained in the different estimators based on MPS determination and Least Probable Symbol LPS considerations.image