A new source model and accurate rate control algorithm with QP and rounding offset adaptation

Rate control plays an important role in regulating the encoding bit rate to meet the bandwidth and storage requirement. Most existing works regulate the bit rate by adjusting the quantization step size. We propose to incorporate a new dimension: the quantization rounding offset into a rate control algorithm. Based on our previous work of multi-pass fine rate control, in this work, we present a unified one-pass rate control algorithm that jointly adjusts the quantization step size and the rounding offset for high bit rate accuracy. Unlike the quantization step size that has a limited number of choices, the rounding offset is a continuously adjustable variable that allows the rate control algorithm to reach any precision in principle. Our extensive experimental results show that the proposed algorithm greatly improves the rate control accuracy at almost no extra computational complexity.