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#296 Mixed methods
Hello Igor/team,
Is there any feature or method that adjusts the compression method for files in a /single pass/ based on the file type and whether or not the file is already compressed, e.g. when zipping up a directory that contains "txt" files and "mp3" files, can I use "normal" compression for "txt" and "store" for "mp3" in the same pass?
The /same pass/ is important because this is spanned archive so cannot be updated once created. I have previously addressed this by creating two spanned archives, one with an include list for already compressed types, and one with an exclude list for already compressed types. However, that is not very elegant.
Another possible way to deal with this is to first create a temporary mega-archive using multiple passes and then created a spanned archive using 'store', but not really elegant either.
Would be grateful for any suggestions in case there is anyone feature/switch I have overlooked.
Thanks!
Compressed files are not big problem for lzma2.
External plugin Smart7z has this feature.
I'm not sure how to interpret "not big problem". I think we have an 80/20 question here. With one use case I have, running with LZMA2, mx=5 takes almost 4 times as long as mx=1 for only 20% compression gain. What I tried to do with one workaround (two separate backup volumes) is avoid having the tool spend time figuring out it had files it wasn't goint to get good compression results on. Obviously, that someone has produced a plugin for this suggests there is a perceived need for it (thanks Dec). Of course, I want to have my cake and eat it, fast and maximum compression ...
The bigger problem with span, is that they cannot be updated. One way I thought of approaching that is to archive files into a file whose name is based on a hash of the file name. That way you could keep a collection of small/portable archives similar to span but which maintain the ability to update.