Quote:
Originally Posted by rkomar
I'm not sure that an application can know the answer to whether it will reduce or not without going ahead, compressing a file and comparing the sizes. Are there existing programs that do it another way?
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It would be darn near impossible to predict if a file will shrink when compressed or not. It's much easier to predict that a file WON'T shrink. Files that are already compressed generally won't compress any/much more on a second attempt, and many will actually increase in size. So one might be able to predict that a ZIP file, a PNG file, etc. will not benefit from additional compression attempts (much, if any). You could look at the contents of a file and bounce that against the planned compression algorithm and maybe predict shrinkage or not - but that's pretty much the same thing as just doing the compression in the first place and then looking at the results. Some applications compress their files as a normal course of business. That's just what the developers programmed them to do. An outside separate compression program is not going to know that, and will not be able to predict that those application's files shouldn't be touched.