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Thread: xdelta

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    xdelta

    What about this pre-compressor?
    http://xdelta.org/
    License GPL

    What about to add this to Win/arc? I know ARC have own delta
    Last edited by John; 14th July 2008 at 01:16.

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    not a pre-compressor

    i belvei that Xdelta is not a pre-compressor.

    its a program to make patch files.

    ef.
    you have 1gb file of version 1.0
    and 1gb file of version 1.1

    now instead of transferring the entire new 1gb file.

    xdelta finds the difference of v1.0 and v1.1 and make a patch file that only contains the difference.

    That way you only need to transfer the small patch file when upgrading form 1.0 to version 1.1 and no the entire file.



    The delta filter in ARC is something total different

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    Quote Originally Posted by SvenBent View Post
    i belvei that Xdelta is not a pre-compressor.

    its a program to make patch files.

    ef.
    you have 1gb file of version 1.0
    and 1gb file of version 1.1

    now instead of transferring the entire new 1gb file.

    xdelta finds the difference of v1.0 and v1.1 and make a patch file that only contains the difference.

    That way you only need to transfer the small patch file when upgrading form 1.0 to version 1.1 and no the entire file.



    The delta filter in ARC is something total different
    Yes, xdeta is more like the REP

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    AFAIU Xdelta is no way like REP. If you'll "preprocess" two almost equal (except first 5 bytes) 100mb files with REP you'll get ~100mb + 5 bytes file. Xdelta must produce ~5 bytes file (+file names, offsets, etc.).

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    Quote Originally Posted by nimdamsk View Post
    AFAIU Xdelta is no way like REP. If you'll "preprocess" two almost equal (except first 5 bytes) 100mb files with REP you'll get ~100mb + 5 bytes file. Xdelta must produce ~5 bytes file (+file names, offsets, etc.).
    Some way it is - both remove large repetitions.

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    Quote Originally Posted by IsName View Post
    Some way it is - both remove large repetitions.
    *Sigh*

    rep work on ONE file and finds repetitions inside the one single file.
    The one single file is then smaller


    Xdelta finds difference between two files. and make a third files that contains the differences
    It is used to make a patch file... just like its written on the god damned linked site.


    Its two total different things

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    Programmer Bulat Ziganshin's Avatar
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    i agree with isname - algos are close

    but usage is different. so it's hard to use it in fa

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    I'm not going to discuss algo's is I'm clearly the underdog there.

    for me rep works like some LZ compression with big dictionaries.
    and Xdelta works like XOR'ing two files


    But saying they are "close" then we are not having the same definition of close.


    its reminds me of an old forum argument about what ever xXx was close to james bond.

    They both contains Techno enhanced cars and a secret agent.
    but then again there where so many differences.

    close similar and the alike are all subjective words.


    Anyway i fail to see where something like Xdelta could improve compression unless you are compression similar files.
    and solid achieve with something like REP would gain a similar benefits. (and in this contents you might say xdelta and REp indeed are similar)

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    What about a test list like:
    rep vs xdelta with 7-zip or uharc?

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    i recently downloaded Xdelta. Seems i confused it with another program with a similar name. Jyst FYI.
    So my previous statements is hereby withdrawn until further notice.

    i will try testing rep vs xdelta in combination with RZM soon

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    Member Vacon's Avatar
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    Hello everyone,

    just to make it clearer to interested readers:
    John talked about -> http://xdelta.org/
    Sven had in mind -> http://linux.die.net/man/1/xdelta
    (if I understood him correctly)
    So one of the two sites / programmers has choosen a name that was not unique, and so this discussion here became confusing.

    Best regards!

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    It's the same autor:
    From xdelta.org:
    posted by jmacd @ 11:40 PM
    From the man linux page:
    Author: Joshua P. MacDonald, jmacd
    The options of xdelta:
    standard options:
    -0 .. -9 compression level
    -c use stdout
    -d decompress
    -e compress
    -f force overwrite
    -h show help
    -q be quiet
    -v be verbose (max 2)
    -V show version
    memory options:
    -B bytes source window size
    -W bytes input window size
    compression options:
    -s source source file to copy from (if any)
    etc..

  13. #13
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    I don't know, it may be great for backup purposes, but for standalone compression it's not that great:

    ENWIK8
    44.108.899, 108s compression, 4s decompression

    then packed with 7-zip - 35 MB, 7z alone without xdelta - 24 MB.
    I am... Black_Fox... my discontinued benchmark
    "No one involved in computers would ever say that a certain amount of memory is enough for all time? I keep bumping into that silly quotation attributed to me that says 640K of memory is enough. There's never a citation; the quotation just floats like a rumor, repeated again and again." -- Bill Gates

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    You need two files to compare , it's like make a patch
    [source to analize] [2nd file to analize] [final data to patch]
    And then you don't need the [2nd file to analize] ,
    Pack the [source to analize] and [final data to patch]

    Sometimes can work great and sometimes not, who knows

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    Well, I can't Putting more than two files on commandline doesn't work (which is right according to usage "[input [output]]" displayed at runtime).
    EDIT: I see, -s, but still I can't use it in my benchmark as it's single file compression only.
    I am... Black_Fox... my discontinued benchmark
    "No one involved in computers would ever say that a certain amount of memory is enough for all time? I keep bumping into that silly quotation attributed to me that says 640K of memory is enough. There's never a citation; the quotation just floats like a rumor, repeated again and again." -- Bill Gates

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    08-01-2011
    xdelta 3.0.0 source code is available http://code.google.com/p/xdelta/downloads/list

    A minor change in behavior from previous releases. If you run xdelta3 on source files smaller than 64MB, you may notice xdelta3 using more memory than it has in the past. If this is an issue, lower the -B flag

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