A New Rate Control Scheme for H.263 Images

Abstract

In some image/video applications, the variable bi rate (VBR) image bitstream will be transmitted over a constant bit rate (CBR) transmission channel, in which a channel buffer is employed. In this study, a new rate control scheme for H.263 images is proposed. By using the proposed rate control procedure for the frame layer, the target bits for each image frame is obtained. Then the proposed just-noticeable-distortion (JND) preprocessing is applied on all the INTRA mode MBs. A new bit estimation model using the average weighted square sum of the zig-zag ordered DCT (discrete cosine transform) coefficients is proposed. The Optimal quantization parameter (QP) of each MB (macorblock) within the MB layer is determined by using the Lagrange multiplier. Based on the simulation results obtained in this study, the proposed approach can meet the target bit rate more accurately, keep a lower buffer fulness, and have a better temporal resolution than TMH9, whereas the PSNR of the proposed approach is as good as that of TMN9.