Subscribe to AfterDawn's weekly newsletter.
OptimFROG DualStream is an extension on top of OptimFROG lossless audio compression, but it is a lossy compression. It is aimed at filling the big gap between perceptual coding and lossless coding. The goal is to offer real transparent audio coding (not only perceptually transparent) at half or less the bitrate generally used by lossless coding, and also to permit progressive consistent increase of the quality level, until lossless coding is reached.
Using a correction file with the audio file with OptimFROG DualStream lossy compression will provide lossless decoding, a feature also available with WavPack.