Single-pass frame-level constant distortion bit allocation for smooth video quality

Quality fluctuation has a major negative effect on subjective video quality. A desirable single-pass frame-level constant-distortion bit allocation scheme is proposed in the paper for smooth video quality throughout the video sequence. The average distortion of previous coded frames is taken as the target distortion for the current frame. According to the linear rate control algorithm, the distortion and rate are exponential and linear function of the number of zero coefficients, respectively. Based on the target distortion and the distribution of the absolute DCT coefficients, we then derive the closed-form formulas for estimating the number of zero coefficients and the slope /spl theta/ in the linear rate control function as well as the bit budget for the current frame. Experimental results show that the proposed constant-distortion (but variable rate) bit allocation scheme provides much smoother video quality on all testing video sequences than constant bit allocation scheme.