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Overview
Source coding and channel coding are two opposing forces that present significant challenges
in error-resilient adaptive lossless data compression. Source coding tries to decorrelate the
input sequence as much as possible by removing redundant information, while channel coding
introduces additional correlation by adding the information in order to protect against errors.
Due to their devastating effects, errors in adaptive data compression have been a long-standing
open problem. As a result, the non-resilience of adaptive data compression has hindered its use
in many applications. However, joint source-channel coding has emerged as a possible solution
to the problem. We have developed a novel joint source-coding algorithm capable of correcting
errors in the popular Lempel-Ziv'77 scheme without losing any practical compression power.
This is possible since the LZ'77 (as well as gzip) encoder does not completely remove all
redundancy. The inherent additional redundancy left by LZ'77 encoder is used succinctly by a
channel coder (e.g., Reed-Solomon coder) to protect against a limited number of errors. In
addition to this, the scheme proposed here is perfectly backward-compatible, that is, a file
compressed with our error-resilient LZ'77 can be still decompressed by a common LZ'77 decoder.
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