libwavpack

libwavpack is a completely open audio compression format providing lossless, high-quality lossy, and a unique hybrid compression mode. Although the technology is loosely based on previous versions of libwavpack, the new version 4 format has been designed from the ground up to offer unparalleled performance and functionality. In the default lossless mode libwavpack acts just like a WinZip compressor for audio files. However, unlike MP3 or WMA encoding which can affect the sound quality, not a single bit of the original information is lost, so there's no chance of degradation. This makes lossless mode ideal for archiving audio material or any other situation where quality is paramount. The compression ratio depends on the source material, but generally is between 30% and 70%. The hybrid mode provides all the advantages of lossless compression with an additional bonus. Instead of creating a single file, this mode creates both a relatively small, high-quality lossy file that can be used all by itself, and a "correction" file that (when combined with the lossy file) provides full lossless restoration. For some users this means never having to choose between lossless and lossy compression!

libwavpack features include:

* Compatible with virtually all PCM audio formats including 8, 16, 24, and 32-bit ints; 32-bit floats; mono, stereo, and multichannel; sampling rates from 6 to 192 kHz (and non-standard rates)
* Multiplatform support including Windows, Linux, and OS X
* Instantly seekable and streaming capable (and gapless)
* ReplayGain (including WavPack file scanner and compatible plugins)
* Uses ID3v1 and APEv2 tags for metadata (including ReplayGain)
* Error-tolerant block format conducive to hardware decoding
* Optional "asymmetrical" mode for improved compression
* MD5 audio checksums for verification and identification
* Unique hybrid mode (provides high quality lossy + "correction" file
* Dynamic noise shaping (dns) for optimum quality at lower hybrid bitrates
* Hybrid mode now operates as low as 2.25 bits/sample (or 196 kbps for CD audio)
* Free and open source with easy to use library interface and unrestrictive license (BSD)
* Intuitive command line interface (with wildcards and destination directory)
* Small, efficient executable (no large programs or dlls to install)
* Special "low latency" version available for custom applications
* Self-extracting archives with cuesheets (Windows only)
* Fully backward compatible to WavPack 1.0
* Java decoder now available
* Complete piping support