libaec is a free implementation of the Golomb-Rice compression method as described in the Recommendation for Space Data System Standard 121.0-B-2. Another implementation of this standard is szip which is already supported by HDF5 and thus netCDF4.
The main reason to use this compression method is that is is very fast for both compression and decompression and yields a good compression ratio for typical low entropy data.
libaec has a szip API compatibility layer and can be used as a drop-in replacement for szip. It also has its own API which allows you to use more recent additions to the standard and the coding of data streams among other things.
The code is available under a BSD license. As you may know, NASA holds a patent on parts of the method. Our understanding from communication with NASA's Chief Patent Counsel is that they have effectively abandoned this patent and anyone is free to make 'use of its teachings and claims'. See doc/license.txt for further information on this matter.
All szip related tests in HDF5 pass with libaec and several people on campus here tested the code with HDF5 and GRIB. Still, this being the first release we would be very interested to get feedback on possible bugs and incompatibilities.
You can download the code from:
German Climate Computing Centre