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Thread: "decompilling" iso

  1. #1
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    Wouldn't it be possibel to decompile a iso image to improve compression

    step
    1. extract the files form the iso.
    2. make a file which contains info of where the file was in the iso
    3. replace the area where the files was stored in the iso with zero'es

    that way the files from within the iso could be handle be best possible compression engine/filters.


    at decompression we just decompress the individual files. and put them back into the iso according to the file from step 2


    i could definitely use such for backup of dvdbased games (as precompt and rzm doesn't handle big files

  2. #2
    Administrator Shelwien's Avatar
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    Of course its possible and of course it'd be useful.
    But the common trouble with this kind of standard formats
    is that they're supported on the OS level everywhere,
    so nobody messes with them, so no useful sources, like
    dumpers or something, available.

    http://en.wikipedia.org/wiki/Universal_Disk_Format
    http://www.ecma-international.org/pu...T/Ecma-167.pdf
    http://www.osta.org/specs/pdf/udf260.pdf
    http://www.iso.org/iso/iso_catalogue...csnumber=26783
    http://sourceforge.net/projects/linux-udf/
    and also I have the sources of win2k udfs.sys driver, but can't say its helpful.

    That's all I could find and sources are really messy and not standalone, and
    manuals are traditionally full of water.

    So, if you find some standalone open source dvd extraction or archival tool
    with built-in UDF format parser, then I might be able to patch it into a image
    splitter/merger utilities. Also there're rumors about some philips udf verificator,
    but I wasn't successful in finding it.
    Or else you have to wait until someone extracts the relevant information from
    the specifications and implements it from scratch.
    Or - the best bet - just do it yourself.

    Edit: Same applies to ISO9660 CD images, except that's a completely different format with the same availability problems.

  3. #3
    Programmer Bulat Ziganshin's Avatar
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    Igor Pavlov has high-prioity plan to support UDF format in 7-zip

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    Administrator Shelwien's Avatar
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  5. #5
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    Quote Originally Posted by Shelwien
    Or - the best bet - just do it yourself.
    Only a slight issues. I have Almost zero knowledge in programming

  6. #6
    Administrator Shelwien's Avatar
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    Well, it appears that this philips' utility is close to the dumper which I wanted, so maybe I'd use it sometime.

    > I have Almost zero knowledge in programming

    Its not about programming really, most of required work here is information extraction - reading the specification,
    comparing it to the dvd image hex-view, and writing your own format description.
    Then,. having the necessary info, writing a rough splitter would be a matter of minutes.
    But now it requires manually processing the 168-page specification or/and megabyte of C sources.

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