This paper evaluates the coding efficiency of the HM 13.0 HEVC rate-distortion optimizing (RDO) encoder before and after the context-adaptive binary arithmetic coding (CABAC) engine is replaced with the context-based arithmetic coding (CBAC) engine of AVS 2.0. In addition, the rate errors are controlled by varying the bit length of the fractional part for the estimated bit in the rate estimation table. The experimental result shows that the CBAC engine provides 0.21% BD-rate reduction on average, compared to the CABAC engine in the HEVC Test Model (HM) 13.0 encoder, when the bit length of the fractional part of the estimated rate is 3.