This paper describes an error resilient source coding approach for variable length codes. The scheme to be presented has been designed to make the Huffman coded scalefactor data of MPEG-2/4 Advanced Audio Coding (AAC) more resilient against transmission errors and has been adopted by the ISO/IEC 14496-3 (MPEG-4 Audio) standard. The scalefactor coding scheme enables bidirectional decoding and enhanced error detection, taking into account the differential coding approach used for scalefactor data. Along with the basic ideas associated with the coding scheme, the paper presents appropriate error concealment strategies which allow for sophisticated scalefactor reconstruction. Subjective test results are presented in order to illustrate the performance of the approach in the presence of adverse channel conditions.
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