Forcing 32-bit zip compression?

  • Rich MacDonald

    Rich MacDonald - 2014-02-04

    I am creating zip files to be used with java 6, which does not support 64-bit zip files.
    I am storing large collections of small images in a single uncompressed zip file.
    10,000 to 1,000,000 images. Image file sizes are 1KB - 20KB. Resultant zip files up to 10GB.
    If 32-bit compression fails, I can break up the files in other ways.

    How does 7zip choose between 32-bit and 64-bit?
    I am seeing odd results. One 800MB zip file used 64-bit, while another 1200MB file used 32-bit.

    Is there any way to force 32-bit compression, then fail if impossible?

  • Igor Pavlov

    Igor Pavlov - 2014-02-05

    7-Zip uses ZIP64, if there are 65535 files or more.

    Last edit: Igor Pavlov 2014-02-05
  • Rich MacDonald

    Rich MacDonald - 2014-02-06

    Thank you


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