Check data type, if type is double or float apply szip, else apply zlib
: sounds perfect to me !
Thanks,
Franck
Note : don't know why but I thought H5Pset_deflate / H5Pset_szip where
supposed to be applied on the whole file (I got this wrong)
Le 2016-01-11 16:45, Miller, Mark C. a écrit :
From: Hdf-forum <hdf-forum-boun...@lists.hdfgroup.org [1]> on behalf
of houssen <hous...@ipgp.fr [2]>
Reply-To: HDF Users Discussion List <hdf-forum@lists.hdfgroup.org
[3]>
Date: Monday, January 11, 2016 2:00 AM
To: "hdf-forum@lists.hdfgroup.org [4]" <hdf-forum@lists.hdfgroup.org
[5]>
Subject: [Hdf-forum] Mixing use of ZLib and SZip compression
When using HDF5, is it possible to mix ZLib and SZip compression ?
If
yes how ?
Yes. You can have a single hdf5 file with some datasets that are
compressed with zlib and others compressed with szip.
A single dataset compressed with both zlib and szip? I imagine that
*might* be possible. Never tried it. Not sure why you'd want to do
it.
But, I can't think if a reason HDF5 might balk at it except if
they've
added logic to explicitly forbid it. For reasons you mention below,
don't think szip *after* zlib would "work" at all. But, zlib *after*
szip might.
My understanding is that:
1. ZLib can compress any data (char *, int, double, ...)
Yes, its a byte-level compressor. Doesn't care if those bytes
comprise an array of floats, doubles, ints, chars, etc.
2. SZip is dedicated to
can't recall but that sounds plausible/right.
"MAC_OUTLOOK_ATTRIBUTION_BLOCKQUOTE" style="BORDER-LEFT: #b5c4df 5
solid; PADDING:0 0 0 5; MARGIN:0 0 0 5;">
According to HDF5 doc, we have:
1. to use H5Pset_deflate to use ZLib (deflate algorithm)
2. to use H5Pset_szip to use SZip
volving it meet its requirements.
My understanding is that, if I use both H5Pset_deflate and
H5Pset_szip,
then:
1. data (whatever they are) which are NOT numbers will be compressed
with ZLib
2. numbers will be compressed with SZip
I don't think it works that way. If you apply *both* filter
DF5 library has some logic to handle them specially? If not *and*
if
you want the behavior you describe here. Its easy to impliment your
own sort of merged zlib/szip filter yourself that does something
like…
* Check data type. If type is double or float, apply szip, else
li>
Hope that helps. I am 99% certain what I've just written is accurate
;)
Mark
Links:
------
[1] mailto:hdf-forum-boun...@lists.hdfgroup.org
[2] mailto:hous...@ipgp.fr
[3] mailto:hdf-forum@lists.hdfgroup.org
[4] mailto:hdf-forum@lists.hdfgroup.org
[5] mailto:hdf-forum@lists.hdfgroup.org
_______________________________________________
Hdf-forum is for HDF software users discussion.
Hdf-forum@lists.hdfgroup.org
http://lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org
Twitter: https://twitter.com/hdf5
