New bufferless rate control for high efficiency video coding

As a crucial component of video compression, rate control regulates the encoding bitrates of compressed bitstreams to meet channel bandwidths while obtaining optimum encoding quality. In this research, we investigate rate control techniques for High Efficiency Video Coding (HEVC/H.265) and propose a new Proportional-Integral-Derivative (PID) based direct rate control algorithm for HEVC/H.265. The objective is to achieve accurate bitrate control for real-time networked video applications. Based on the PID control theory, the proposed algorithm first performs target bit allocation, and then directly controls actual compression bitrates to get close to target encoding bitrates. Different from conventional rate control approaches, a buffer is not adopted in the proposed rate control algorithm which naturally reduces encoding delay and improves real-time response. When compared with the rate control scheme adopted by HEVC/H.265 reference software, our algorithm achieves superior performance according to the experimental results. Specifically, our proposed algorithm improves rate control accuracy up to 23.43%, and achieves higher encoding quality up to 3.47 dB.