THE EREC - AN ERROR-RESILIENT TECHNIQUE FOR CODING VARIABLE-LENGTH BLOCKS OF DATA

Many source and data compression schemes work by splitting the input s ignal into blocks and producing variable-length coded data for each bl ock. If these variable-length blocks are transmitted consecutively, th en the resulting coder is highly sensitive to channel errors. Synchron ization code words are often used to provide occasional resynchronizat ion at the expense of a some added redundant information. This paper i ntroduces the error-resilient entropy code (EREC) as a method for adap ting existing schemes to give increased resilience to random and burst errors while maintaining high compression, The EREC has been designed to exhibit graceful degradation with worsening channel conditions, Th e EREC is applicable to many problems and is particularly effective wh en the more important information is transmitted near the start of eac h variable-length block and is not dependent on following data. The ER EC has been applied to both still image and video compression schemes, using the discrete cosine transform (DCT) and variable-length coding, The results have been compared to schemes using synchronization code words, and a large improvement in performance for noisy channels has b een observed.