This page (http://www.hdfgroup.org/HDF5/doc/UG/10_Datasets.html) states that "The library determines what filters must be applied and in what order." Does that mean that no matter which order I set deflate, fletcher, and shuffle on a DCPL, the library will process these in a manner that makes the most sense (in this case, it would be shuffle then deflate with fletcher on either side)?
Also, when I use H5Pget_filter, what is the significance of the ordering of the filters that are retrieved (by index), if any? Is it just the order that I added the filters and/or does this affect the order that the filters are actually applied in the pipeline?
David McCloskey
Lead Programmer Analyst
Software Development
Core Engineering
Nuclear Fuel
Westinghouse Electric Company
Energy Center
4350 Northern Pike
Monroeville, PA, 15146, USA
Phone: +1 (412) 374-3789
Fax: +1 (412) 374-4500
Email: mcclosdl@westinghouse.com
Home Page: www.westinghousenuclear.com
Hi David,
This page (http://www.hdfgroup.org/HDF5/doc/UG/10_Datasets.html) states that "The library determines what filters must be applied and in what order." Does that mean that no matter which order I set deflate, fletcher, and shuffle on a DCPL, the library will process these in a manner that makes the most sense (in this case, it would be shuffle then deflate with fletcher on either side)?
Also, when I use H5Pget_filter, what is the significance of the ordering of the filters that are retrieved (by index), if any? Is it just the order that I added the filters and/or does this affect the order that the filters are actually applied in the pipeline?
Actually, this is an error in our documentation (which I've filed a bug for). The filters are actually applied in the order that the application calls the H5Pset_<foo> routines. So, if you call H5Pset_shuffle(), then H5Pset_deflate(), the shuffle filter is applied first, then the deflate filter is applied. This plays out as you'd expect for the H5Pget_filter() call and the filters are indexed in the order you called the H5Pset_<foo> routines (i.e. the shuffle filter would be at index 0 and the deflate filter would be at index 1 in my example above).
Quincey
···
On Dec 8, 2009, at 3:29 PM, McCloskey, David L. wrote:
David McCloskey
Lead Programmer Analyst
Software Development
Core Engineering
Nuclear Fuel
Westinghouse Electric Company
Energy Center
4350 Northern Pike
Monroeville, PA, 15146, USA
Phone: +1 (412) 374-3789
Fax: +1 (412) 374-4500
Email: mcclosdl@westinghouse.com
Home Page: www.westinghousenuclear.com
_______________________________________________
Hdf-forum is for HDF software users discussion.
Hdf-forum@hdfgroup.org
http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
