The FAAC project includes the AAC encoder FAAC and decoder FAAD2. It supports several MPEG-4 object types (LC, Main, LTP, HE AAC, PS) and file formats (ADTS AAC, raw AAC, MP4), multichannel and gapless en/decoding as well as MP4 metadata tags. The codecs are compatible with standard-compliant audio applications using one or more of these profiles.
Speex is a patent-free compression format designed especially for speech. It is specialized for voice communications at low bit-rates in the 2-45 kbps range. Possible applications include Voice over IP (VoIP), Internet audio streaming, audio books, and archiving of speech data (e.g. voice mail).
Freedup finds and eliminates duplicate files by linking them, and thus reduces the amount of used disk space within one or more file systems. By default, hardlinks are used on a single device, symbolic links when the devices differ. A set of options allows you to modify the methods of file comparison, the hash functions, the linking behavior, and the reporting style. You may use batch or interactive mode. Freedup usually only considers identical files, but when comparing audio or graphics files, you may elect to ignore the tags.
The True Audio (TTA) codec is a simple realtime lossless audio compressor. It performs lossless compression on multichannel 8, 16, and 24 bit data of Wav audio files. The compression ratios depend on the type of music file being compressed, but the compression size will generally range between 30%-70% of the original. TTA supports both ID3v1 and ID3v2 information tags.