For lossless compression, the only way you can know how many times you can gain by recompressing a file is by trying. It’s going to depend on the compression algorithm and the file you’re compressing. Two files can never compress to the same output, so you can’t go down to one byte. How could one … Read more
Take a look at dictzip. It is compatible with gzip and allows coarse random access. An excerpt from its man page: dictzip compresses files using the gzip(1) algorithm (LZ77) in a manner which is completely compatible with the gzip file format. An extension to the gzip file format (Extra Field, described in 2.3.1.1 of RFC … Read more
Most generic compression algorithms work with a one-byte granularity. Let’s consider the following string: “XXXXYYYYXXXXYYYY” A Run-Length-Encoding algorithm will say: “that’s 4 ‘X’, followed by 4 ‘Y’, followed by 4 ‘X’, followed by 4 ‘Y’” A Lempel-Ziv algorithm will say: “That’s the string ‘XXXXYYYY’, followed by the same string: so let’s replace the 2nd string … Read more
gunzip file.txt.gz in Terminal.
Node v0.6.x has a stable zlib module in core now – there are some examples on how to use it server-side in the docs too. An example (taken from the docs): // server example // Running a gzip operation on every request is quite expensive. // It would be much more efficient to cache the … Read more
I had the same problem and found two different solutions (see this thread for more details). Both reduced the size of my uncompressed PDF dramatically. Pixelated (lossy): convert input.pdf -compress Zip output.pdf Unpixelated (lossless, but may display slightly differently): gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -dNOPAUSE -dBATCH -dQUIET -sOutputFile=output.pdf input.pdf Edit: I just discovered another option (for … Read more
The extention .zst means that the archive is compressed by zstd. https://github.com/facebook/zstd The tar command has an option -I (–use-compress-program) to specify a command for compression/decompression. You can use it as follows. $ tar –use-compress-program=unzstd -xvf archive.tar.zst
Very simple to test. I took your js, put them in different files and ran gzip -9 on them. Here’s the result. This was done on a WinXP machine running Cygwin and gzip 1.3.12. -rwx—— 1 xxxxxxxx mkgroup-l-d 88 Apr 30 09:17 expanded.js.gz -rwx—— 1 xxxxxxxx mkgroup-l-d 81 Apr 30 09:18 minified.js.gz Here’s a further … Read more
If you’re really interested in the technical details, check out the source code: png_optimizer.cc jpeg_optimizer.cc webp_optimizer.cc For PNG files, they use OptiPNG with some trial-and-error approach // we use these four combinations because different images seem to benefit from // different parameters and this combination of 4 seems to work best for a large // … Read more
Use the -J compression option for xz. And remember to man tar 🙂 tar cfJ <archive.tar.xz> <files> Edit 2015-08-10: If you’re passing the arguments to tar with dashes (ex: tar -cf as opposed to tar cf), then the -f option must come last, since it specifies the filename (thanks to @A-B-B for pointing that out!). … Read more