Rate distortion modeling and adaptive rate control scheme for high efficiency video coding (HEVC)
This paper explores a novel rate control scheme for HEVC, based on Pre-analysis Sum of Absolute Transformed Differences (pSATD). The needs for improving the rate control method of HEVC have been observed since the latest method proposed in JCT-VC H213 is still using the classical quadratic model which is implemented in H.264/AVC. The same rate control scheme on different coding structures will definitely lead to a poor performance. The proposed method aims at selecting accurate quantization parameters (QP) for inter frames according to the target bit rate. After encoding video sequences exhaustively, a strong linear relationship between the pSATD and bpp (bit per pixel) is revealed. Thus, a rate control scheme for HEVC with parameters updating adaptively is proposed accordingly. Apart from that, a new rate and distortion model are established using pSATD and Quantization Step Size (QStep). By minimizing the cost function built based on the proposed rate-distortion (R-D) model, the optimization problem can be solved properly. According to the optimal solution, a bit allocation scheme with consideration of pSATD and buffer status is formed. The experimental results illustrate that the proposed method outperforms JCT-VC H213 implemented in HEVC reference software for all test sequences, up to 19% coding gain can be achieved.