Re: [netcdfgroup] please try out the netcdf daily snapshot for opendap, hdf4-reading, hdf5-reading, szip compression, etc.

  • To: Jeff Whitaker <jswhit@xxxxxxxxxxx>
  • Subject: Re: [netcdfgroup] please try out the netcdf daily snapshot for opendap, hdf4-reading, hdf5-reading, szip compression, etc.
  • From: Ed Hartnett <ed@xxxxxxxxxxxxxxxx>
  • Date: Mon, 19 Oct 2009 04:59:48 -0600
Jeff Whitaker <jswhit@xxxxxxxxxxx> writes:

>
> Ed:  I'd like to try out the szip compression, but I only see
> instructions on how to build with szip enabled.  Are there any docs
> yet showing to use szip instead of zlib for compression?
>
> -Jeff

Howdy Jeff!

Can you tell me why you prefer szip to zlib deflation? 

>From C, use nc_def_var_szip to set up szip compression on a var (after
it is defined, but before any enddef is called.) There is also an
nc_inq_var_szip function, for completeness, but it is not necessary to
know that a variable is zipped when reading it, as the unpacking is
automatic. See the C docs for more:
http://www.unidata.ucar.edu/software/netcdf/docs_snapshot/netcdf-c.html#nc_005fdef_005fvar_005fszip

In F90, there are two new parameters to the nf90_def_var and
nf90_inquire functions, "option_mask" and "bits_per_pixel", which allow
you to turn on szip and control its operation. Documentation here:
http://www.unidata.ucar.edu/software/netcdf/docs_snapshot/netcdf-f90.html#NF90_005fDEF_005fVAR

Please let me know how it works for you!

Thanks,

Ed
-- 
Ed Hartnett  -- ed@xxxxxxxxxxxxxxxx



  • 2009 messages navigation, sorted by:
    1. Thread
    2. Subject
    3. Author
    4. Date
    5. ↑ Table Of Contents
  • Search the netcdfgroup archives: