WavPack

WavPack is a free and open-source lossless audio compression format.

WavPack compression (.WV files) can compress (and restore) 8-, 16-, 24-, and 32-bit fixed-point, and 32-bit floating point audio files in the .WAV file format. It also supports surround sound streams and high frequency sampling rates. Like other lossless compression schemes, the data reduction rate varies with the source, but it is generally between 30% and 70% for typical popular music and somewhat better than that for classical music and other sources with greater dynamic range.

WavPack also incorporates a "hybrid" mode which still provides the features of lossless compression, but it creates two files: a relatively small, high-quality, lossy file (.wv) that can be used by itself; and a "correction" file (.wvc) that, when combined with the lossy file, provides full lossless restoration. This allows the use of lossy and lossless codecs together.

A similar "hybrid" feature is also offered by OptimFROG DualStream, MPEG-4 SLS and DTS-HD Master Audio.

David Bryant started development on WavPack in mid-1998 with the release of version 1.0 (1998-08-15). This first version compressed and decompressed audio losslessly, and it already featured one of the best efficiency vs. speed ratios among lossless encoders.

Very soon after the release of version 1.0, v. 2.0 (2 September 1998) was released, featuring lossy encoding (using only quantization of prediction residue for data reduction - no psychoacoustic masking model was applied to the stream).

In 1999, version 3.0 (12 September 1999) was released, with a new "fast mode" (albeit with reduced compression ratio), compression of raw (headerless) PCM audio files, and error detection using a 32-bit cyclic redundancy check.