一种H.264码率控制的改进算法

码率控制作为H.264里极为重要的一个环节,在参考软件Joint Model(JM)中已给出算法.由于JM模型采用线性模型预测MAD以获得模式选择所需要的量化步长,这种算法运算量较大且MAD预测不够准确,因而造成码率控制的结果不准确.本文针对这种缺点,在原有算法的基础上提出一种新的基于预测激励和时空相关的MAD预测算法,同时还给出一种根据修正空间来调节码率的方法.仿真结果显示,采用这种改进算法的H.264编码器不仅取得更低比特率,而且有效提高了PSNR,控制的精确度也有所提高.

Rate control in terms of modification space for H.264

One of the important phases of H.264 is rate control,the algorithm of which is provided in reference software Joint Model(JM).As JM model uses linear model prediction MAD to achieve magnitude step,the computational cost of this algorithm is high and MAD prediction is inaccurate,then results in imprecise rate.Thus,the present paper introduces a kind of new prediction innovation based on time and space related MAD prediction algorithm.Meanwhile,a method of rate adjusting in terms of modification space is proposed.The results of simulation illustrate that the H.264 coder with this method achieves lower bit rate while increasing PSNR effectively and precision as well.