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Thread: bzip2 dictionary size

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    Member Wladmir's Avatar
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    bzip2 dictionary size

    Is there any way to use the bzip2 compression in 7zip with dictionary size greater than 900kb?

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    No.

    BZip2 format has 9 sizes of blocks to choose, biggest one is 900 KB. Compression can only be improved using some preprocessors like Srep.

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    @Piotr_Tarsa

    you are right for the original bzip2 1.0.5

    but for pbzip2 (parallel bzip2)
    from http://compression.ca/pbzip2/
    (fully compatible with the original bzip2)

    it is possible to set a blocksize bigger then 900k

    Usage: pbzip2 [-1 .. -9] [-b#cdfhkp#qrtVz] <filename> <filename2> <filenameN>
    -b# : where # is the file block size in 100k (default 9 = 900k)

    the effect we can see at the following graf

    http://compression.ca/pbzip2/bench-itanium2.gif

    you can see also http://encode.dreamhosters.com/showthread.php?t=253

    best regards

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    I think that with only small changes to BZip2 source code one can release a version with any block size. But official BZip2 supports only 100 KB - 900 KB blocks.

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