7zip Ultra LZMA2 compression

Question

How can I convert this settings into command?

Here are the results:

// Manual Compression (see the image above)
Compressed Size: 12,647,451 bytes

// Ultra
7z a -t7z Files.7z -mx9 -aoa
Compressed Size: 12,676,886 bytes

// LZMA2
7z a -t7z Files.7z -m9=LZMA2 -aoa
Compressed Size: 14,237,515 bytes  

I am looking here:
http://sevenzip.sourceforge.jp/chm/cmdline/switches/method.htm

I am about to put this in a batch file.

Solution 1

Your command line should be at least:

7z a -t7z Files.7z -m0=lzma2 -mx=9 -aoa

Note that you'll get better compression when using 1 or 2 threads, not 8. So, even closer to your GUI settings (ms : solid, d : dictionary size, mhe : encrypt header (file names), p : password)

7z a -t7z -m0=lzma2 -mx=9 -aoa -mfb=64 -md=32m -ms=on -d=1024m -mhe -pSECRET

Solution 2

It's hard to get the same result, but this is the best I can get so far:

7z a -t7z Files.7z -m0=BCJ2 -m1=LZMA2:d=1024m -aoa

Solution 3

For those who are on unix system, this is how I achieved this.

7z a -t7z -m0=lzma2 -mx=9 -mfb=64 -md=1024m -ms=on destination.7z Source

My source: http://manpages.ubuntu.com/manpages/artful/man1/7z.1.html

Solution 4

This command is creating for me the same output like the ultra configuration with the ui. I have found it in the documentation under examples. 560MB to 29MB (binary data with a lot duplicate files)

7za.exe a output.7z ./input -mx

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Comments

[Aquarius Power]

did it provide better compression?

[fiberOptics]

there would be only less than 1MB difference compared to using GUI.

[Aquarius Power]

btw, on my test this simple 7z a -t7z -mx9 worked better, but in my case the file was too small and may not work the same for you... anyway kgb -9 won but is slow... (oh btw I am on linux..)

[Jeroen Wiert Pluimers]

I'm not sure as of which 7z version it barfs on -d=1024m, but this works for version 16.04 on Windows: 7z.exe a -t7z -m0=lzma2:d1024m -mx=9 -aoa -mfb=64 -md=32m -ms=on. I also append ` -sdel` to the options for moving files to an archive.

[milivojeviCH]

Using 1, 2 or 3 threads uses the same amount of memory for compression which makes me think that they all share the same dictionary. Based on my tests, there's no drop in compression efficiency for up to 3 threads.

[Able Mac]

-aoa is an extraction option. It means don't overwrite files that already exist on disk. It is ignored when compressing files to an archive.

[Nilesh]

What is the significance of -t7z?

[tricasse]

@Nilesh: -t7z = archive type 7z