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Thread: Why Does NanoZip Compress This File More Than PAQ8 And cmix?

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    Why Does NanoZip Compress This File More Than PAQ8 And cmix?

    Hi Guys,

    According to any and all benchmarks, PAQ8PX/PXD and cmix compress files better than NanoZip's -cc option, right?

    Can anyone help me understand why NZ does much better on the attached file? Here are some quick results:

    I can't post it because the file size is too big. Here is the file: http://www61.zippyshare.com/v/26398490/file.html

    Code:
    FFADMIN.EXE   6,141,074 
    NZ            5,015,668 
    CMIX          5,292,665 
    MCOMP (PWCM)  5,379,116 
    PAQ8PX_v69    5,401,019 
    PAQ8PXD_v15   5,447,329 
    PAQ8PXD_v12   5,447,434 
    UDA           5,471,662
    Any explanation?
    Last edited by comp1; 28th September 2014 at 00:15.

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    7-zip LZMA2 ultra (with a dictionary large than 6MB) compresses to 5.290.711. My guess is that the data fits better a dictionary model.

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    I noticed that actually a little while ago...

    So would this imply that NanoZip's -cc options uses something other than pure CM? Perhaps LZP? Something is going on in NanoZip that isn't going on with these other CM compressors.

    Any ideas?

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    This file is FoxPro exe. About 5,8MB of it. Encoded. It actually contains jpg, some small bitmaps other files. But its encoded.
    And there are many files that paq8* cant compress that well.
    KZo


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    Quote Originally Posted by kaitz View Post
    This file is FoxPro exe. About 5,8MB of it. Encoded. It actually contains jpg, some small bitmaps other files. But its encoded.
    And there are many files that paq8* cant compress that well.
    Kaido,

    So because of the encoding of the data, CM compressors fail in comparison to LZ-type compressors?

    Thanks for helping me understand.

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    I would say that being CM or LZ doesn't matter here. It's the flexibility of filters and special models and reliability of content detection that play roles here.

    LZMA has the option to model the lowest bits of offsets. Maybe the data is structured into blocks that are sized by power of two, thus enabling LZMA to show its strength. AFAIK PAQ-like compressors don't bother much about offsets.

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    Quote Originally Posted by Piotr Tarsa View Post
    I would say that being CM or LZ doesn't matter here. It's the flexibility of filters and special models and reliability of content detection that play roles here.

    LZMA has the option to model the lowest bits of offsets. Maybe the data is structured into blocks that are sized by power of two, thus enabling LZMA to show its strength. AFAIK PAQ-like compressors don't bother much about offsets.



    Agreed

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    Cool

    Quote Originally Posted by Piotr Tarsa View Post
    I would say that being CM or LZ doesn't matter here. It's the flexibility of filters and special models and reliability of content detection that play roles here.
    Yup. So far as I can tell NZ wins are due to content detection and filters.
    Last edited by cbloom; 3rd August 2016 at 20:37.

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