OptimFROG was designed to aim at the best audio compression possible. OptimFROG asymptotically has the best ratios available for lossless audio compression. Includes sophisticated, computationally intensive, original compression algorithm.

OptimFROG obtains asymptotically the best lossless audio compression ratios. It has Windows and Linux versions, fully featured input plug-ins for the foobar2000, Winamp2, Winamp3, dBpowerAMP, XMPlay and XMMS audio players (with bitstream error resilience, ID3v1.1 and APEv2 read tagging support), optimal support for all integer PCM wave formats up to 32 bits and an extensible streamable (error tolerant) compressed format. It is also fast, the default mode encodes CD quality audio data at 12.4x real-time and decodes at 17.4x real-time on AMD Athlon XP 1800+ (the fastest mode encodes at 28.1x real-time and decodes at 24.7x real-time).

The compression ratios which can obtained with OptimFROG are generally ranging from 25% (silent classical music) to 70% (loud rock music) of the original audio file size. This is less compared with around 13% obtained with high quality MP3 files (~176 kb), but you have the great advantage of archiving and listening at perfect copies of your original music.

OptimFROG uses a new audio compression technology, the generalized stereo decorrelation concept (together with the optimal predictor), which was first introduced with OptimFROG 4.0b in December 2001. At the time of its introduction, the new technology yielded significant better (~1.5%) compression than existing state of the art lossless audio compressors.

Features of OptimFROG :

- asymptotically the best lossless audio compression ratios
- optimal support for all integer PCM wave formats up to 32 bits
- fully featured foobar2000, dBpowerAMP, Winamp2, Winamp3, XMPlay, and XMMS input plug-ins for playback
- fast operation, default mode encodes CD quality audio data at 12.4x real-time and decodes at 17.4x real-time on AMD Athlon XP 1800+
- Win32 and Linux command line versions
- simple to use, but powerful Windows GUI front-end, Kermit (made by Speek) available at http://home.wanadoo.nl/~w.speek/kermit.htm
- extensible, streamable compressed format, tagging compatible
- optimize option, further improving compression at no decoding cost
- backward compatible with version 4.2x (decode only)
- 64 bits large file support under Win32
- full pipe support for encoding and decoding
- full raw file support
- quick verify compressed file integrity function
- compatible with Exact Audio Copy, with ID3v1.1 tagging
- extensible command line format
- multiple file processing on the same command line, with wildcards
- option to store MD5 of raw PCM input data and function to check it
- option to delete source file after successful operation
- option to copy source file time stamp to destination file
- bitstream error resilience and transparent real-time recovery
- fast seek with intelligent caching for plug-ins
- ID3v1.1 and APEv2 read tagging support for plug-ins
- streaming support (playing HTTP streams) for foobar2000 plug-in
- Replay Gain compatible plug-ins for foobar2000 and Winamp3
- fully featured SDK for using compressed files in any application

Changes in OptimFROG 4.600ex :

- the highnew, extranew, bestnew modes and maximumcompression get slightly better compression (on average 0.1%)
- added --experimental option, enabling advanced experimental compression, which is NOT backward compatible with any previous 4.5xx versions
* use with any mode for greatly improved compression for some files (on average, 0.60% better compression for Audio CDs)
* extranew speed: encoding < 35% slower, decoding < 11% slower
* can be also used together with --maximumcompression
- [other] the foobar2000 input plug-in now supports cue sheets (thanks to Artur for suggestions and testing)
- [other] official GUI interface using FroG is ready, it will be included in the upcoming OptimFROG installer (thanks to Daniel, the FroG author; available at http://frog.objective-view.de/)
- [other] parsing WAV files with invalid headers is in the works

Changes in OptimFROG 4.520 b1 :

- the port to Darwin/ppc was verified and is now released (thanks to krmathis for testing)
- added --tailsize option to specify the tail bytes for raw files
- fixed MD5 internal computing for big endian architectures
- added run-time self integrity architecture check
- fixed --check_audition option which used a condition too strict and did not correct all the corrupted zeros

Changes in OptimFROG 4.509 :

- enhanced the WAV file parser to automatically detect uneven size chunks without the required alignment byte (non-conforming files)
- slight general speed enhancement with around 2%
- added the --headersize option to specify the starting header size for raw files, also useful for raw data alignment
- enhanced the raw file parser to add the last few bytes to the tail instead of rejecting the file for having a non-divisible data size
- enhanced automatic generation of file extension at decoding (using the header data to detect if the file is WAV or raw)
- added full support for the data types SINT8, UINT16, UINT24, UINT32
- fixed a very rare encoder bug where an invalid compressed block was created for some silence-like data. Thanks to Olivier for reporting