Hierarchical B-frames can bring high coding performance when introduced into H.264/AVC.However,the traditional rate control schemes can not work efficiently in such new coding framework.This article presents a rate control algorithm for hierarchical B-frames in H.264/AVC.Taking the feature of the dyadic hierarchical coding structure into consideration,the proposed algorithm includes group of pictures (GOP) layer,temporal layer and frame layer bits allocation.After frame layer bits allocation is complete,frame layer quantization parameters (QP) determination strategy is responsible for calculating the final QP.Experimental results show that compared with other rate control algorithms,the proposed one can improve the coding performance and reduce the mismatch of target bit rate and real bit rate.
A parity check matrix construction method for constructing a low-density parity-check (LDPC) codes over GF(q) (q>2) based on the modified progressive edge growth (PEG) algorithm is introduced. First, the nonzero locations of the parity check matrix are selected using the PEG algorithm. Then the nonzero elements are defined by avoiding the definition of subcode. A proof is given to show the good minimum distance property of constructed GF(q)-LDPC codes. Simulations are also presented to illustrate the good error performance of the designed codes.
CHEN Xin , MEN Ai-dong, YANG Bo, QUAN Zi-yi School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China
