Free compression software for linux

RPM Delta Compression Virtual Update Repository is an experiment to explore the possibility of significantly reducing the bandwidth required to apply updates to a Fedora installation.
This software includes a server which provides a virtual update repository to clients such as yum, up2date, or other update tools. RPM Delta Compression Virtual Update Repository also includes a utility to create and maintain a RPM delta repository.
The server will attempt to generate the update RPM from a small delta file applied to a locally stored RPM from the original distribution.
Enhancements:
- This version utilizes the SuSE deltarpm tool as the underlying delta generator.
- It features both HTTP virtual update of the RPM repository (using Tomcat servlet container) and command line tools for generating update RPMs from a delta repository.

libcomprex library transparently handles automatic compression and decompression of files and archives located locally, online, or even in other compressed archives.

The API is similar to Cs built-in file access functions, which provides a smooth transition to libcomprex.

libcomprex can also open uncompressed files, making it a good replacement for the native file access functions.

libcomprex can currently open ar, bzip2, cpio, gzip, tar, and zip files. It supports basic archive writing in some formats. The API is very volatile, and development should be done against the CVS version.

CSSTidy is an opensource CSS parser and optimizer. The project is available as executeable file (available for Windows, Linux and OSX) which can be controlled per command line and as PHP script (both with almost the same functionality).
In opposite to most other CSS parsers, no regular expressions are used and thus CSSTidy has full CSS2 support and a higher reliability.
Main features:
- colours like "black" or rgb(0,0,0) are converted to #000000 or rather #000 if possible. Some hex-codes are replaced by their colour names if they are shorter.
- a{property:x;property:y;} becomes a{property:y;} (all duplicate properties are merged)
- margin:1px 1px 1px 1px; becomes margin:1px;
- margin:0px; becomes margin:0;
- a{margin-top:10px; margin-bottom:10px; margin-left:10px; margin-right:10px;} becomes a{margin:10px;}
- margin:010.0px; becomes margin:10px;
- all unnecessary whitespace is removed, depending on the compression-level
- all background-properties are merged
- all comments are removed
- the last semicolon in every block can be removed
- missing semicolons are added, incorrect newlines in strings are fixed, missing units are added, bad colors (and color names) are fixed
- property:value ! important; becomes property:value !important.
Why optimise?
If you optimise your CSS code you have faster loading pages and lower traffic costs. So both you and your visitors benefit from an optimisation. If you are interested in a faster loading webpage, websiteoptimization.com might also be an interesting resource.
Compression ratio
The compression ratio mostly depends on the level of whitespace-removal. Using standard whitespace-removal (which preserves the readability) the compression ratio often is 30% and more. In theory the compression ratio can be 99,99% but only very "stupid" stylesheets will allow those ratios. Also have a look at the examples.
Apart from compression
If a high compression is not important for you, you can also use CSSTidy to format or fix CSS code for a higher browser compatibility. Apart from the 4 default templates you can specify custom templates so that you can easily format a lot of CSS code using your own coding style. Other features are sorting and changing the case of selectors and properties.
Enhancements:
- Note: This is the last version of CSSTidy. If youd like continue maintaining it, let me know.
- FS#146 - Quotes
- FS#147 - Universal selector before classes, IDs and attribute selectors
- FS#150 - Wrong trasformation of a big integer value
- FS#144 ? !important rule
- FS#140: Fixing Values of Invalid properties
- [ 1745894 ] @media merge strangeness (cssTidy.exe version)
- FS#143: Save some more bytes

Since there are none right now for Linux [well there still is ext2comp, but ext2 is getting a bit old and the patches are NOT compatible with ext3] I wrote this thing. Thanks to FUSE and using compFUSEd you can have a compressed FS on top of any fancy must have FS on Linux.
Simple? This fs is not suited for large files! Files are compressed as a whole. No clever strategy was used to split the files in chunks of fixed. Later maybe.
Overlay? Files are compressed an decompressed on the fly but the actual storage is done in the directory of an underlying fs. This underlying fs takes care of space allocation, fragmention, etc...
Main features:
- Transparant read and write compression (again, I know ;)
- Configuration file (very simple one)
- Can use ZLIB, LZO or BZIP2, set in config file. You can not change the compression once the files are created!
- User defined blacklist of file extensions that should not be compressed, set in config file. So that we do not try to compress jpeg or Xvid files. Common file types are included by default in the blacklist (see cf_file.c).
- Files smaller that 4096 bytes are not compressed. First because bzip2 has problems with that! And second because I _think_ that the underlying fs will allocate a block of 4096 bytes anyway to store the compressed data anyway (no?).
- Any cleverness? Not really, uncompressible files are not compressed. Unchanged files are not recompressed (whoaa!...:( ).
- Since version 0.04 (cf-200528614.tgz) threading works (after 12 October 2005).
Enhancements:
- A new "minimum size for compression" parameter has been added.
- Incorrectly marked uncompressable chunks have been fixed.
- The code to persist the filesystem info between mounts has been fixed.
- This release has graceful handling of compression lib failure.
- It has dynamically sized file mapping (internal mapping).

OptimFROG is a lossless audio compression program. OptimFROG project main goal is to reduce at maximum the size of audio files, while premitting bit identical restoration for all input. It is similar with the ZIP compression, but it is highly specialized to compress audio data.
OptimFROG obtains asymptotically the best lossless audio compression ratios. It has Windows and Linux versions, fully featured input plug-ins for the foobar2000, Winamp2, Winamp3, dBpowerAMP, XMPlay and XMMS audio players (with bitstream error resilience, ID3v1.1 and APEv2 read tagging support), optimal support for all integer PCM wave formats up to 32 bits and an extensible streamable (error tolerant) compressed format. It is also fast, the default mode encodes CD quality audio data at 12.4x real-time and decodes at 17.4x real-time on AMD Athlon XP 1800+ (the fastest mode encodes at 28.1x real-time and decodes at 24.7x real-time).
The compression ratios which can obtained with OptimFROG are generally ranging from 25% (silent classical music) to 70% (loud rock music) of the original audio file size. This is less compared with around 13% obtained with high quality MP3 files (~176 kb), but you have the great advantage of archiving and listening at perfect copies of your original music.
OptimFROG uses a new audio compression technology, the generalized stereo decorrelation concept (together with the optimal predictor), which was first introduced with OptimFROG 4.0b in December 2001. At the time of its introduction, the new technology yielded significant better (~1.5%) compression than existing state of the art lossless audio compressors.
Main features:
- asymptotically the best lossless audio compression ratios
- optimal support for all integer PCM wave formats up to 32 bits
- fully featured foobar2000, dBpowerAMP, Winamp2, Winamp3, XMPlay, and XMMS input plug-ins for playback
- fast operation, default mode encodes CD quality audio data at 12.4x real-time and decodes at 17.4x real-time on AMD Athlon XP 1800+
- Win32 and Linux command line versions
- simple to use, but powerful Windows GUI front-end, Kermit (made by Speek)
- extensible, streamable compressed format, tagging compatible
- optimize option, further improving compression at no decoding cost
- backward compatible with version 4.2x (decode only)
- 64 bits large file support under Win32
- full pipe support for encoding and decoding
- full raw file support
- quick verify compressed file integrity function
- compatible with Exact Audio Copy, with ID3v1.1 tagging
- extensible command line format
- multiple file processing on the same command line, with wildcards
- option to store MD5 of raw PCM input data and function to check it
- option to delete source file after successful operation
- option to copy source file time stamp to destination file
- bitstream error resilience and transparent real-time recovery
- fast seek with intelligent caching for plug-ins
- ID3v1.1 and APEv2 read tagging support for plug-ins
- streaming support (playing HTTP streams) for foobar2000 plug-in
- Replay Gain compatible plug-ins for foobar2000 and Winamp3
- fully featured SDK for using compressed files in any application

Sdictionary is a cross-platform dictionary project uses own Sdict dictionary format. Sdictionary includes Sdict, the main program and two simple applications: Jotter and Data.
Unlike ptkdic or gtkdic no MySQL needed, so you can work with dictionary files directly. Currently it is known to work under Unix, Win32 and Symbian OS.
Main features:
- Open Source, .dct format is also open and described in documentation
- Unicode, all words and articles are stored in utf8
- Two index levels: short and full
- Using compression
- Tools to convert from text file to .dct and vice versa
- Simple Web dictionary included into package
- C library framework
- Perl API (Sdict.pm module)
- Simple Jotter and Data applications

The Horde Application Framework is written in PHP, and provides the common tools a Web application requires: classes for dealing with preferences, compression, browser detection, connection tracking, MIME, and more.
The Horde Framework does not provide any significant end user functionality and it provides a base for other applications and tools for developers. You will probably want to install some of the available Horde applications, such as IMP (a webmail client), or Kronolith (a calendar).
Enhancements:
- This is a security release that fixes a cross site scripting vulnerability and improves protection against phishing attempts.