基于区间划分的快速重归一化算法

Fast renormalization algorithm based on interval division

重归一化是H．264／AVC标准二进制算术编码器的一个关键部分，在算术编码器中，重归一化计算量很大，严重制约了算术编码器的效率；同时重归一化算法是一个按位操作过程，很多情况下通过运行一次重归一化算法并不能完成重归一化操作，因此消耗了大量编码时间。为了减少编码时间，针对影响重归一化速度的瓶颈问题，提出了一种基于区间划分的快速重归一化算法。根据重归一化循环次数提出六种不同的区间划分标准来去除H．264／AVC重归一化算法中消耗大量编码时间的按位操作过程；通过去除重归一化的循环过程，使得算法在单位时间内向编码流中输出更多的比特数，能够更好地满足实时性的要求。实验表明，快速重归一化算法在原重归一化算法基础上减少了21．9％-26．7％的重归一化次数和14．5％～33．7％的编码时间。

Renormalization is a key part of BAC in H. 264/AVC standard. In BAC, the renormalization has seriously constrained the efficiency of the arithmetic coding because its computational complexity is high. Renormalization algorithm is a bitwise-operation procedure. In many cases, the renormalization operation can＇ t be finished by running renormalization algorithm for one time, so it is consuming a lot of coding time. In order to reduce the coding time, this paper introduced a fast renormalization algorithm based on interval division to deal with the bottleneck problem in renormalization. According to the number of cycles in renormalization loop, this fast renormalization algorithm introduced six different interval division standards to replace time-consuming, bitwise-operation procedure. At the same time, through removing the cycle of renormalization procedure, the algorithm could output more bits to coding stream in unit time and better meet the requirements of real-time. Experiment results indicate that the proposed fast renormalization algorithm enables reduce the number of renormalization algorithm by 21.9% 26.7% and their corresponding run time by 14.5% -33.7%.