A novel macroblock-layer rate-distortion model for rate control scheme of H.264/AVC

The purpose of rate control is to adjust an encoder so that the amount of encoded bits can match the amount of desired bits. In this paper, we focus on the rate control of an H.264/AVC encoder. We first analyze the relation between the quantization parameter, MAD, and the coded bit number. We also analyze the encoding of header bits. Based on these analyses, we build up a new rate-distortion model. Moreover, we use motion vectors to predict the MAD value. Based on these modifications, we may better predict the quantization parameter and the amount of encoded bits. In experiments, our approach not only improves the stability of encoder buffer but also makes an obvious improvement of visual quality.