高速指数哥伦布编解码器的VLSI设计与实现

指数哥伦布编码是H.264/AVC标准和AVS标准中熵编码的重要组成部分,其硬件实现好坏直接决定了编码器熵编码的性能。文中根据哥伦布编码和解码的特点,设计了一种高速的哥伦布编解码器。首先,用查找表的方式代替了首1检测等复杂操作,通过查找直接得出要编解码码字的长度;直接取出特定的要操作的数据,同时进行相应的操作,代替了传统的先移位,再进行相应操作的方式,使得指数哥伦布编解码器的关键路径变短,速度变快。其次,对哥伦布编解码器采用了多级流水的方式,进一步提升了主频。最后,在virtex5平台上进行测试,该编解码器的吞吐率均可达到400MPixel/s。这将远胜于当今图像解码专用芯片的编解码速度,也为图像高速压缩提供了硬件实现基础。

VLSI Design and Implementation of High-speed Ex-Golomb Encoder and Decoder

The exponential Golomb(Ex-Golomb) algorithm is the important part of entropy coding in H.264/AVC and AVS video compression standards.The implementation of Ex-Golomb encoder will determine the whole entropy encoder.A high-speed exponential Golomb encoder and decoder architecture is designed,according to the characters of Ex-Golomb algorithm.First of all,the LUT is adopted instead of the complex operations of first-1-detection to get the length of code from LUT directly,and take the specific bits out of the registers.Other operations are carried out at the same time,which is different from the traditional algorithms of shifting the specific bits of the registers first and then executing appointed operations.The critical path of the Ex-Golomb encoder and decoder is shortened.Then pipelining technique is introduced to accelerate the encoder and decoder by dividing the module though registers.At last,the Ex-Golomb encoder and decoder are implemented and tested on platform of Virtex5.Tests results show that the throughput rate of both encoder and decoder can reach 400 MPixel/s,which is much higher than that of the current special chips.