WavPack is a free and open-source lossless audio compression format and application implementing the format. It is unique in the way that it supports hybrid audio compression alongside normal compression which is similar to how FLAC works. It also supports compressing a wide variety of lossless formats, including various variants of PCM and also DSD as used in SACDs, together with its support for surround audio. Features WavPack compression can compress (and restore) 8-, 16-, 24-, and 32-bit fixed-point, and 32-bit floating-point PCM audio files in the .WAV file format. It also supports surround sound streams and high 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. Hybrid mode WavPack also incorporates a "hybrid" mode, which still provides the features of lossless compression, but 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. Summary Open-source, released under a BSD-like license Multiplatform Error robustness Fast encoding Higher compression ratios than other widely used (FLAC/ALAC) open-source lossless audio codecs Streaming support Supports multichannel audio and high resolutions Native support in WavPack 5.x for compressing Direct Stream Digital without converting the source file to PCM. Hybrid/lossy mode Hardware support (provided by Rockbox firmware) Metadata support (ID3, APE tags; APE tag is the preferred format) Supports RIFF chunks Compatible with ReplayGain Ability to create self-extracting files for the Win32 platform Supports 32-bit floating-point streams Supports embedded CUE sheets Includes MD5 hashes for quick integrity checking Can encode in both symmetrical and asymmetrical (slower encoding to speed up decoding) modes History 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