depends on what kind of files.
depends what speed you need.
depends on whether lossless compression or not.
modern common type archivers 7Zip is pretty effective, if you specify the maximum key compression on random data.
to get around, they can significantly increase the time compression when a slight increase in compression efficiency.
already compressed video and sound files - external archivers is almost not compressed. to compress them - you need to transcode.
pictures - if it's a JPEG too, you don't really will shrink. PNG - you can still try overtaking in JPEG.
compression of media files (video, sound, pictures) is not described as external and internal (the file will be converted without the possibility of early recovery, but the person will be perceived almost as the original).
it is possible to choose between "to compress better, have more to lose" or "compress worse less to lose."
well universal archiver - look for the word "fractal compression".
it is the most efficient known today.
but duuuuuuuuuuuuuuuuuude slow. for example, the fact that 7zip will compress for 15 minutes then a fractal algorithm can be compressed and 10 hours with the advantage in the amount of 30%. Is it worth it?
alfonso56 answered on June 5th 19 at 21:07
The most effective and at the same time, slowest General purpose compression - PPMdsupported by 7-zip archiver.
For images JPEG is the best compression gives Lepton.