H.261视频编码协议中BCH前向纠错码的快速算法

介绍了H.261视频编码协议中的BCH(511,493)纠错码的编码和纠错原理,分析了采用软件实现经典算法效率低的原因,提出了纠正2位随机错误的快速算法。与经典除法算法相比,快速算法使整机运算效率平均提高20倍以上,能够满足实时视频通信系统的要求。本算法已成功运用在PSTN和ISDN可视电话中,而且这些快速算法的实现方法对其他运算量较大的纠错编码也有较高的参考价值。

Quick Algorithm for BCH Error-correcting Decoding of H.261 Video Coder Recommendation

As BCH is a kind of linear error_correcting code with good performance up to now,it has been used widely.But for the relatively longer codes,it cost large computation,so special hardware is alwayes employed in real_time communication.But in low_cost communication system or desktop communication system with no hardware support,the most urgent problem is how to complete the computation of BCH code efficiently,namely the algorithm efficiency of BCH code.In this paper,firstly,coding method and error_correction theory of BCH(511,493) error_correcting in video coding recommendation H.261 are introduced,then the low efficiency in classical division algorithm with software completion is analyzed.Subsequently,a kind of quick algorithm on correcting 2_bit random errors is offered.With practical evidence,this algorithm can increase the whole running speed at least 20 times than the classical division algorithm and meet the requirement in real_time video communication.It has been successfully used in PSTN and ISDN videophone.