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Thread: ECM filtering makes MMA compresssion worse ?

  1. #1
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    ECM filtering makes MMA compresssion worse ?

    i've got two bin cdimage with some data and audiotracks.

    MMA is better then rzm with any combination of delta/rep filters

    However if i run ECM on the files the mma compression get worse
    So MMA resulrs in smaller files then ECM + MMA.

    i just wonder how that can be as ECM just simply remove data and does not compress the data before MMA

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    Ups forgot some info

    Code:
    file1.bin         = 592 MB (621.506.592 bytes)
    file1.bin.ecm     = 558 MB (585.950.453 bytes)
    file1.bin.mma     = 376 MB (395.288.806 bytes)
    file1.bin.ecm.mma = 433 MB (455.076.413 bytes)
    Code:
    file2.bin         = 675 MB (708.041.376 bytes)
    file2.bin.ecm     = 632 MB (663.241.687 bytes)
    file2.bin.mma     = 493 MB (517.314.341 bytes)
    file2.bin.ecm.mma = 532 MB (558.659.217 bytes)
    Last edited by SvenBent; 24th January 2009 at 21:37.

  3. #3
    Programmer osmanturan's Avatar
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    As far as I know, MMA blindly compresses the given file. It assume that the file is aligned in 16-bits. So, maybe ECM can brake the alignment by removing ECC codes. Let me state it for clearing something:
    Code:
    Before ECM:
    XX [ECC] AA AA AA AA
    
    After ECM:
    XX AA AA AA AA
    [ECC]=ECC block, AA=analog data, XX=any other data. After removing ECC block, starting of the first AA block index can be odd. So, MMA can get worser compression. You can prove that idea by adding padding at the beginning of the file before compressing with MMA.
    BIT Archiver homepage: www.osmanturan.com

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    aah so instead of having even bytes (and thereby some product of 16bits) i might end up with uneven bytes in the front, which moves the 16bits channels 8 bit out of sync with the MMA compression ?

    I might try to make a simple padding to see if it works

    thanx alot.

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    Member m^2's Avatar
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    MM offers offset switch, so you don't have to do anything yourself.
    Code:
    mm:oNumber
    ADDED: Sorry, I missed A and thought you're talking about Bulat's MM.
    My post is irrelevant then.
    Last edited by m^2; 24th January 2009 at 23:24.

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    Osman is right. MMA assumes 16-bit-aligned wave input.

    Sorry, atm there are no plans to improve on that. MMA was just a demo release. In the meantime I've designed other special compressors and filters - like RGB, dynamic dictionary, improved EXE, ...
    Maybe someday I'll find time to bundle them together into one hell of a compressor.

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    Programmer osmanturan's Avatar
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    Quote Originally Posted by Christian View Post
    Sorry, atm there are no plans to improve on that. MMA was just a demo release. In the meantime I've designed other special compressors and filters - like RGB, dynamic dictionary, improved EXE, ...
    Maybe someday I'll find time to bundle them together into one hell of a compressor.
    Sound is exciting. Toffer and me are at edge of beating CCMX in both speed and compression ratio and we need another good competitor in the scene
    BIT Archiver homepage: www.osmanturan.com

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    Stephan Busch's Avatar
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    Dear Sven,

    please also keep in mind that audio cd images do not contain any error correction codes, so using ECM here gives no gain.

    Only data cd images and video cd images contain error correction codes.

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    Quote Originally Posted by Stephan Busch View Post
    Dear Sven,

    please also keep in mind that audio cd images do not contain any error correction codes, so using ECM here gives no gain.

    Only data cd images and video cd images contain error correction codes.
    I'm perfectly aware of that. my CD images contains both data and audiotracks. and to my knowledge VCD's are also without the extra ECC that a data tracks has.

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