Using variable-length error-correcting codes in MPEG-4 video

Reversible variable length (RVL) codes are used in MPEG-4 video coding to improve its error resilience. Algorithms used to design variable-length error-correcting (VLEC) codes are modified so as to construct efficient RVL codes with a smaller average length than those found in the literature. It is also shown that RVL codes are a special (weak) class of VLEC codes. Consequently more powerful VLEC codes can be used in the MPEG-4 codec and it is shown that performance gains of up to 20 dB in peak signal to noise ratio (PSNR) can be obtained using a soft-decision sequential decoder with relatively simple VLEC codes. This increase in performance is obtained at the expense of an order of magnitude increase in decoding complexity