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[Roman]

4.048d
fixed: softwarelists can lack some possible mergings
fixed: possible assertion during delta checks

[Dirstac]

Add Zstandard support for zip archives and CHDs
https://github.com/mamedev/mame/pull/11827

MAME adds zstabdard support, will cmp consider supporting this compressor?

[Roman]

well....for chds it won't play a role since decompression is only done when the belonging option is activated and then chdman is used.

For zips it would mean that the data inside the zip uses a different compression mechanism while the general zipstructure is the same, so reading shouldn't be a problem too.

When it comes to testing or unpacking it depends if ZipArchive (the used 3rd party library) is able to work with it which I haven't tested yet. When it comes to adding files to an archive, most likely a standard mode is used so that the newly added file inside the archive won't be Zstandard anymore (unless a direct copy of compressed data is used). The same applies to the new scanner/rebuilder where you might have the chance that bit7z (which reuses 7z) might already be able to decompress/compress Zstandard compressed files inside zips....have to check that. I can contact the authors of both to see if such a feature (if missing) can be added in a future release.

[Dirstac]

Okay.

[Roman]

would be nice however if someone prepares a zip file with some zStandard compressed files in it...would save me some time :-)
Again: we don't talk about .zstd files but zip with zStandard compression method.

[haynor666]

I did some tests with 7zip that has zstandard built. zstandard appears to be a sometimes a little bigger sometimes a little smaller with comparison to 7z ZLMA2. RAR it's even again a little bigger than zstandard or 7zip but it's faster.

https://mega.nz/file/801HzBSD#dWS5qbyqgqiY2mzgEeaV_wgNHztjsgcMEyv2PCYxEqI

[Roman]

Thanks, I will have a look

[Roman]

I've contacted the author of ZipArchive and there is a good chance that zStandard will be included.
Don't know if I add a workaround (maybe via unrar.dll, have to check that) before that but I doubt that users need the support for zips (chds come for free...) so quickly...

[haynor666]

I was curious about new compressor so after tests I added example file because You ask it
Personally I'm more interested in chds delta since it saves a lot more space. Besides we already have support for rar and 7z in MAME so zstandard won't change to much I think.

[haynor666]

Latest 7-Zip beta does have included zstandard compression method.