Hi,
I want to send some files which are too big for most mailboxes, and have to compress.
The problem with the GUI-compressor in Mate, is the very low compression level, 35MB get only down to 32MB.
And the split function, which could be a solution, doesn't seem to work either.

Thankful for any help.
Regards,
Dag

Your compression rate depends on what you are compressing. If binary file(s), there won't be much compression. Text compresses quite a bit. There are a lot of choices in Mate` as far as archive type, perhaps another type will compress more? I don't know the rates for each type.

The most recent compression utility seems to be xz. I don't know whether it is included in the GUI compressor. Try it on the command line:
(It's unclear how options -9 and --extreme interact; it might be better to only use one of them)
How so?

It depends on the type of file, as was pointed out already.
Especially if the file is in a compressed format already (.JPG, .MP4, .XDOC etc.) you won't get much additional compression - just 1 or 2%.
If it's a plain text format you can get much more.

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Thanks to both,
second first, it's a binary file (audio)
The split function in the GUI is greyed out.
The problem is, not I (who is more used to use the terminal) but my wife (which has no idea at all) want to compress audio files she wants to send her students. She has no problem with learning, only a big lack of time to do it.
Does xz compress in a Windows-comptabible format?
Her students all use Windows, we here use Mate 18.04.3
(Anyway, I will look up the options to split a file in the terminal)

Binary files will not compress much at all. Better off choosing another audio format that is in itself compressed (mp3 vice Flac) but that involves loss of audio detail which may or may not be acceptable.

I do not know if Windows can deal with anything other than zip natively : I don't use windows so can't speak to its compression capabilities. I know third party apps such as 7zip and winzip work on windows but those are only "zip" format as far as I know.

They are already mp3, 35MB each. So most Mailboxes will refuse.
(I know flac is lossless, but mp3 is the format she gets her students material in).
I will try with split in terminal.
Thanks, I see it as solved

I don't use Windows any more either, but remember something. ZIP works.

winzip seems to be able to handle xz: https://www.winzip.com/win/en/xz-file.html.

However, MP3 is already compressed. split(1) has an option not to split by lines but bytes, so that it might be able to process binary files, but I wonder how the result can be reassembled in Windows.

I think your solution is to use a file sharing facility instead of email to disseminate the files. Dropbox, Onedrive, Google Drive, there are many free of charge options.

1 members found this post helpful.

I think 7z offers good compression (it definitely does more than "just zip") and is available for Windows.
But apparently so is xz.
You should do some testing for yourself; I don't think you'll get much extra compression for a likely already compressed audio format, but it can't hurt to try a few algos, and always compare to zipping up a directory with text files or some such.

I guess the real question is "why is the split function greyed out".
My next step would be to

• identify the package that provides the GUI app in question
• see if it has any "Recommends" or "Suggests", and if one of these might provide the splitting functionality, and if it's installed

But in the end I agree with berndbausch:
You have just found out why people are so wild about cloud storage.

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Thank you,
I have installed but did nothing yet with it.
I will try that out, and am sure I will get along alone now.

7zip has a Linux equivalent too: p7zip
And for instance rar has a Windows (WinRar) and Linux (commandline rar) version.

But almost no compression will do much with .mp3 files, ie:
(from a recent RAR archive I've downloaded, which was created in Windows).