FMA-REP - info and test results (.pa)


  • conexware

    (This article is work in progress)

    What is fma-rep?

    Deduplication filter based on anchor hashing. Technically LZ77, but has no entropy coding, and only longer matches have a chance to be replaced with a reference.

    It has much lower memory requirements than lzma, so can be used to compensate lzma’s smaller window/dictionary size.

    Examples: Official ISOs from Microsoft for Windows 10 Pro and Office 2016:

    Due to large file sizes, and the fact that fma-rep takes a lot less memory than plzma4, it is very useful for large software installation DVDs that have a lot of compressed data already. Best idea is to use large window of fma-rep1 and fast codec, to achieve good compression and yet very fast speed.

    Tests

    AMD FX8320 with 16GB RAM and SSD

    Office 2016 Pro ISO - 1,985,392 kB
    .pa (Zstandard2, x64flt, bcj2, fma-rep1) 36s encode, 37s decode - 1,551,741 kB
    .rar (Normal) 128s encode, 13s decode, 1,892,471 kB

    Windows 10 Pro ISO
    .pa (Zstandard2, x64flt, bcj2, fma-rep1) 87s encode, 77s decode - 3,577,849 kB
    .rar (Normal) 314s encode, 27s decode - 3,838,188 kB

    Sharepoint Server 2013
    .rar (Normal) 369s encode, 15s decode - 2,269,782 kB
    .zip (WZ 21 Normal) - 47s encode, 13s decode - 2,305, 755 kB
    .pa (Zstandard2, x64flt, bcj2, fma-rep1) - 61s encode, 41s decode - 1,955,468 kB


 

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