Mimic 7Zip compression "Ultra" setting

Aspose.ZIP Product Family
1

Hi,

When compressing with 7Zip, it has the “Ultra” option under the compression setting (when used via command line that would be -mx9)
I do not see an option for the ultra compression when using Aspose.Zip.SevenZip.SevenZipArchive

Am I overlooking something?

Thanks,

2

There are not such an feature. Aspose.Zip does not resembles 7-zip here. The only option you can set for LZMA2 compression is dictionary size.
If you need such a feature we may consider to provide it.

3

Yes, this feature should be implemented.
As Aspose contains the Aspose.Zip.SevenZip.SevenZipArchive class to create 7Z files, if it offered the same compressions features like 7-Zip.org, then Aspose’s implementation of 7Zip would be a suitable replacement for using 7-Zip.org.

From my understanding, when I read that Aspose offered the 7Z class it was my impression that it offered the same compression as the freely available 7-Zip.org.

Please read more about that feature here:
https://sevenzip.osdn.jp/chm/cmdline/switches/method.htm

Thanks

4

Ok, will provide advanced settings for LZMA2 method in some release later.

5

@AroundLilac
There is an enhancement: since version 22.8 you can set the number of fast bytes for LZMA2 compression. Find out correspondent SevenZipLZMA2CompressionSettings constructor.

6

Hello,

Can you please share an example utilizing this new feature, please?
To mimic the “Ultra” compression as discussed earlier.

Thank you

7

Hello, there are not exact “ultra” settings as 7-zip has. You can set fastBytes equal to 64 and dictionarySize equal to 64 MB for `SevenZipLZMA2CompressionSettings. This will produce result similar to Ultra settings. However, solid compression and bcj2 filter won’t be applied. Such features may appear in further version.