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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Ed Hartnett wrote:
Ed: From looking at the HDF5 docs I'm pretty sure you mean pixels_per_block, not bits_per_pixel.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? -JeffHowdy 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
http://www.hdfgroup.org/HDF5/doc/RM/RM_H5P.html#Property-SetSzip pixels_per_block is set internally by HDF5. -Jeff
Please let me know how it works for you! Thanks, Ed
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