WavPack is a completely open audio compression format providing
lossless, high-quality lossy, and unique hybrid compression modes.
Although the technology is loosely based on previous versions of
WavPack, the new version 4 format has been designed from the ground up
to offer unparalleled performance and functionality.

By default, lossless mode WavPack 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 is 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!