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Sometimes it's fun to look the results of deliberately broken decompression - you change compressed file a bit and decompress it. Resulting file is broken from a certain position, derailing data: "slightly modified" -> "looks like normal data at the first glance, but weird" -> "gibberish with recognizable parts of source data" -> "pseudorandom" -> zeroes. Sometimes you get funny piece of text (which is still based around the source data by the form, but essentially random).

Usually I use paq8l if I want to play with it (also funny mode when you edit compression level in the file), but the amount of not-completely-broken part is small: it quickly diverges to noise and then zeroes.

  • Are there special programs that read source data and generates "similar" data (with flexible scale of similarity) employing algorithms similar to ones used in compression programs?
  • Can ability to generate interesting noise be connected with compression ratio (approx. "quality") of the algorithm?
  • Can I tell some existing decompresser "don't stop at the end of compressed data, just think up something based on random data (having state inspired by real data)"?

P.S. I already know about Markov chains, I'm looking for more sophisticated things.

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I'm not certain this question is on-topic. I mean, do you have any real goal? –  SamB May 15 '11 at 19:27
    
What is a real goal? It's interesting what will happen there and what will it be similar to. May be it can be used somehow for "real goals" too, for example, for easy generation of content for fuzz tests. –  Vi. May 16 '11 at 11:39
    
The only question left on the now-burninated 'Fun' tag... –  JavaAndCSharp Jul 11 '11 at 16:31
    
Means "SuperUser community does not like fun". This questions also had a counter near "close" button. –  Vi. Jul 12 '11 at 19:19
    
Looks like the answer can come iif I implement such thing myself. –  Vi. Jul 12 '11 at 19:22
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Implemented myself, using lpaq as source.

Link: https://github.com/vi/lpaq1_stream

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