WavPack is a completely open audio compression format providing lossless,
high-quality lossy, and a unique hybrid compression mode.
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.

Homepage:
https://www.wavpack.com/
