Shorten reduces the size of waveform files (such as audio) using
Huffman coding of prediction residuals and optional additional
quantisation.  In lossless mode the amount of compression obtained
depends on the nature of the waveform.  Those composing of low
frequencies and low amplitudes give the best compression, which may
be 2:1 or better.  Lossy compression operates by specifying a minimum
acceptable segmental signal to noise ratio or a maximum bit rate.
Lossy compression operates by zeroing the lower order bits of the
waveform, so retaining waveform shape.

Permission is granted to use this software for decoding and
non-commercial encoding (e.g. private or research use).

If you intend to use shorten, be sure to check the full license,
which can be displayed by "shorten -l".

WWW: http://www.etree.org/shnutils/shorten/