Research On Buffer Management For Video Coding Rate Control

The new video compression coding standard H.264/AVC has employed a series of new technologies to achieve high coding efficiency. Besides, bit-rates control is another essential technique in practical communication applications.Bit-rates control can make the output bit-streams meet the restraints of network bandwidth and buffer capacity by adjusting the parameters in encoder. The technique of buffer management is one of the essential elements in bit rates control, which allocates bit budget for each coding unit reasonably to avoid overflow or underflow of the buffer. Moreover, the bit allocation process may affect the coding performance significantly. Due to the fact that bit rates control is not contained in H.264/AVC standard, it has not been studied sufficiently. Therefore, this paper is engaged in the research of rate control and buffer management techniques for H.264/AVC.This paper has studied a novel quadratic-curve-based buffer management method (QCBM), which is different from the existed one which base on a straight line (SLBM). Considering the video coding features, QCBM employs a quadratic curve to determine the Target Buffer Fullness (TBF) of the current coded frame to allocate bits for P frames more reasonably according to its position in a group of pictures. The quadratic curve is a simple algorithm mode of non-linear decline algorithms. The mode parameters are obtained by the target buffer fullness and the ultimate value. By QCBM, the P-frames closer to the reference I-frame of the group of pictures would have more bit budgets and higher coding qualities, which would enhance the reference frame quality. Thus the performance of video encoder is improved. Experimental results have verified the efficiency of QCBM. Compared with the SLBM implemented in prototype code JM10.2 of H.264/AVC, QCBM method can achieve a gain of 0.15dB~0.22dB. Moreover, the quality fluctuation across coded frames is very small. D PSNR various between 0.04~0.25dB. This method can also be used in other coding standards.