[Issue] 7-Zip Compression not optimal



  • I have tried to achieve the same compression ratio of some downloaded 7-zip archives but despite setting of Power Archiver, I get always a lower compression ratio.
    If I try to open these archive and check the method used, I see that are archives with mixed compression methods.

    So optimized compression of Power Archiver that is supposed to choose the best compression method for each file type is not optimal or there is a smaller dictionary used also with the highest ultra level setting.

    If you want a sample
    -try to download the 64 bit portable windows version of this freeware utility compressed with 7-zip,
    -decompress the file in the downloaded archive
    -compress again with Power Archive with the best 7-zip settings.
    The better that I can get with Power Archiver is 12.9 MB the downloaded archive is 12.1 MB.

    0.8 MB difference on a so small archive is a pretty high difference.

    Power Archiver 16.00.61
    Windows 10 x64 i7 Ivy Bridge 4-core, 16GB RAM


  • conexware

    @SMH17:

    I have tried to achieve the same compression ratio of some downloaded 7-zip archives but despite setting of Power Archiver, I get always a lower compression ratio.
    If I try to open these archive and check the method used, I see that are archives with mixed compression methods.

    So optimized compression of Power Archiver that is supposed to choose the best compression method for each file type is not optimal or there is a smaller dictionary used also with the highest ultra level setting.

    If you want a sample
    -try to download the 64 bit portable windows version of this freeware utility compressed with 7-zip,
    -decompress the file in the downloaded archive
    -compress again with Power Archive with the best 7-zip settings.
    The better that I can get with Power Archiver is 12.9 MB the downloaded archive is 12.1 MB.

    0.8 MB difference on a so small archive is a pretty high difference.

    Power Archiver 16.00.61
    Windows 10 x64 i7 Ivy Bridge 4-core, 16GB RAM

    thank you for the info, it seems that for lzma2 based compression we might not be using all the options for .exe files. We will check it out (lzma setting seems to work fine).



  • No problem. The new Power Archiver version seems very interesting, and I’m doing some test during my free time.


 

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