A Study on Rate Control Techniques of H.264/AVC

• Main Authors: Han-Tsung Chiang, 蔣宗翰
• Other Authors: Sheng-Jyh Wang
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/65962247463409654308

碩士 === 國立交通大學 === 電子工程系所 === 94 === In this thesis, we study the rate control issue of a video compression system. The purpose of rate control is to adjust the encoder so that the number of encoded bits can match the number of desired bits. Here, we focus on the rate control of an H.264/AVC encoder. First, we 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. The bit allocation of each picture is adaptively determined depending on the relations among the picture and its front and rear pictures. This adaptive change can improve the quality and stability of the coded videos. Finally, we use motion vectors to predict the MAD value, which is originally predicted by the JM model. By combining the above methods, we can improve the performance of the buffer in low bit-rate encoding. Especially, with a more accurate R-D model, we can better predict the quantization parameter. In experiments, we show that our approach not only improves the stability of encoder buffer but also makes an obvious improvement of visual quality.