OptimFROG has an impressive list of features, which includes:
Win32 and Linux command-line versions; input plugins for Winamp, foobar2000, dBpowerAMP, XMMS and XMPlay; full raw file support; 64 bits large file support under Win32; full pipe support for encoding and decoding; fast seeking with intelligent caching for plugins, multiple file processing on the same command line using wildcards, and ReplayGain compatible plugins for foobar2000 and Winamp.
The audio compression technology used by OptimFROG is the generalized stereo decorrelation concept, together with the optimal predictor, which was first used by the 4.0b version of OptimFROG in 2001.
The compression rates obtained with OptimFROG are more than satisfactory: from 25% (classical music) to 70% (loud rock music) of the original file size. High-quality MP3s manage to obtain about 13% of the original file size, but on the other hand, the copies created by OptimFROG are perfect and there is no quality difference between the original and the output files.
The last version of OptimFROG was 5.100, and the changes it featured were:
more efficient versions of the highnew, extranew, bestnew, and ultranew modes, named highnew-light, extranew-light, bestnew-light, and ultranew-light, backward compatible with v4.520; add --preset 0 to --preset 10 command-line options for the most efficient compression presets, backward compatible with v4.600; add turbonew, fastnew, and normalnew efficient compression modes to complement the extra mode, backward compatible with v4.520; add the --aca and --acm aliases and the negated form --no-aca; add the minDecoderVersion optional field to the main block, which has the minimum decoder version required to decode the file.— Full list of changes.
OptimFROG is a complex command-line application which produces one of the best lossless audio compression ratios. This tool is recommended to expert users, who know how to use all the advanced features provided by OptimFROG.