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cdo aec compression not mentioned in CDO User Guide

Added by Angelika Heil over 1 year ago

Hello,
I was looking for information on grib2 compression with the libaec libary since aec compression appears to be the default compression when doing

cdo -z szip -copy ifile.grb2 ofile.grb2
cdo sinfov ofile.grb2|head -1

returns:
File format : GRIB2 aec
(for ifile.grb2, you could, e.g. use: original.grib2 from https://code.mpimet.mpg.de/boards/1/topics/13518?r=13526#message-13526)

There is no mentioning of aec in the CDO user guide while it is prominently mentioned in the first sentence of https://code.mpimet.mpg.de/projects/cdo/wiki:
"CDO is a large tool set for working on climate and NWP model data. NetCDF 3/4, GRIB 1/2 including SZIP (or AEC) [...]."

Could you please add some info on aec in the CDO User Guide?

Thanks a lot!
Regards
Angelika


Replies (1)

RE: cdo aec compression not mentioned in CDO User Guide - Added by Ralf Mueller over 1 year ago

Hi Angelika!

libaec is an opensource implementation of the szip compression library. unfortunately szip has very restrictive policy when it comes to redistribution in binary form. that's why CDO uses libaec instead of libszip.

I am not sure, what to write into the CDO user guide about it.

With the current CDO release version, cdo showformat shows GRIB szip no matter if the compressions was done with
  • cdo -z szip or
  • cdo -z aec or
  • cdo -Z
    (1-1/1)